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Add initial prototype.

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This commit is contained in:
Rod Kay
2022-07-31 17:34:54 +10:00
commit 54a53b2ac0
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3-mid/physics/implement/box2d/contrib/src/collision/b2_broad_phase.cpp Normal file
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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_broad_phase.h"
#include <string.h>
b2BroadPhase::b2BroadPhase()
{
m_proxyCount = 0;
m_pairCapacity = 16;
m_pairCount = 0;
m_pairBuffer = (b2Pair*)b2Alloc(m_pairCapacity * sizeof(b2Pair));
m_moveCapacity = 16;
m_moveCount = 0;
m_moveBuffer = (int32*)b2Alloc(m_moveCapacity * sizeof(int32));
}
b2BroadPhase::~b2BroadPhase()
{
b2Free(m_moveBuffer);
b2Free(m_pairBuffer);
}
int32 b2BroadPhase::CreateProxy(const b2AABB& aabb, void* userData)
{
int32 proxyId = m_tree.CreateProxy(aabb, userData);
++m_proxyCount;
BufferMove(proxyId);
return proxyId;
}
void b2BroadPhase::DestroyProxy(int32 proxyId)
{
UnBufferMove(proxyId);
--m_proxyCount;
m_tree.DestroyProxy(proxyId);
}
void b2BroadPhase::MoveProxy(int32 proxyId, const b2AABB& aabb, const b2Vec2& displacement)
{
bool buffer = m_tree.MoveProxy(proxyId, aabb, displacement);
if (buffer)
{
BufferMove(proxyId);
}
}
void b2BroadPhase::TouchProxy(int32 proxyId)
{
BufferMove(proxyId);
}
void b2BroadPhase::BufferMove(int32 proxyId)
{
if (m_moveCount == m_moveCapacity)
{
int32* oldBuffer = m_moveBuffer;
m_moveCapacity *= 2;
m_moveBuffer = (int32*)b2Alloc(m_moveCapacity * sizeof(int32));
memcpy(m_moveBuffer, oldBuffer, m_moveCount * sizeof(int32));
b2Free(oldBuffer);
}
m_moveBuffer[m_moveCount] = proxyId;
++m_moveCount;
}
void b2BroadPhase::UnBufferMove(int32 proxyId)
{
for (int32 i = 0; i < m_moveCount; ++i)
{
if (m_moveBuffer[i] == proxyId)
{
m_moveBuffer[i] = e_nullProxy;
}
}
}
// This is called from b2DynamicTree::Query when we are gathering pairs.
bool b2BroadPhase::QueryCallback(int32 proxyId)
{
// A proxy cannot form a pair with itself.
if (proxyId == m_queryProxyId)
{
return true;
}
const bool moved = m_tree.WasMoved(proxyId);
if (moved && proxyId > m_queryProxyId)
{
// Both proxies are moving. Avoid duplicate pairs.
return true;
}
// Grow the pair buffer as needed.
if (m_pairCount == m_pairCapacity)
{
b2Pair* oldBuffer = m_pairBuffer;
m_pairCapacity = m_pairCapacity + (m_pairCapacity >> 1);
m_pairBuffer = (b2Pair*)b2Alloc(m_pairCapacity * sizeof(b2Pair));
memcpy(m_pairBuffer, oldBuffer, m_pairCount * sizeof(b2Pair));
b2Free(oldBuffer);
}
m_pairBuffer[m_pairCount].proxyIdA = b2Min(proxyId, m_queryProxyId);
m_pairBuffer[m_pairCount].proxyIdB = b2Max(proxyId, m_queryProxyId);
++m_pairCount;
return true;
}

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3-mid/physics/implement/box2d/contrib/src/collision/b2_chain_shape.cpp Normal file
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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_chain_shape.h"
#include "box2d/b2_edge_shape.h"
#include "box2d/b2_block_allocator.h"
#include <new>
#include <string.h>
b2ChainShape::~b2ChainShape()
{
Clear();
}
void b2ChainShape::Clear()
{
b2Free(m_vertices);
m_vertices = nullptr;
m_count = 0;
}
void b2ChainShape::CreateLoop(const b2Vec2* vertices, int32 count)
{
b2Assert(m_vertices == nullptr && m_count == 0);
b2Assert(count >= 3);
if (count < 3)
{
return;
}
for (int32 i = 1; i < count; ++i)
{
b2Vec2 v1 = vertices[i-1];
b2Vec2 v2 = vertices[i];
// If the code crashes here, it means your vertices are too close together.
b2Assert(b2DistanceSquared(v1, v2) > b2_linearSlop * b2_linearSlop);
}
m_count = count + 1;
m_vertices = (b2Vec2*)b2Alloc(m_count * sizeof(b2Vec2));
memcpy(m_vertices, vertices, count * sizeof(b2Vec2));
m_vertices[count] = m_vertices[0];
m_prevVertex = m_vertices[m_count - 2];
m_nextVertex = m_vertices[1];
}
void b2ChainShape::CreateChain(const b2Vec2* vertices, int32 count, const b2Vec2& prevVertex, const b2Vec2& nextVertex)
{
b2Assert(m_vertices == nullptr && m_count == 0);
b2Assert(count >= 2);
for (int32 i = 1; i < count; ++i)
{
// If the code crashes here, it means your vertices are too close together.
b2Assert(b2DistanceSquared(vertices[i-1], vertices[i]) > b2_linearSlop * b2_linearSlop);
}
m_count = count;
m_vertices = (b2Vec2*)b2Alloc(count * sizeof(b2Vec2));
memcpy(m_vertices, vertices, m_count * sizeof(b2Vec2));
m_prevVertex = prevVertex;
m_nextVertex = nextVertex;
}
b2Shape* b2ChainShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2ChainShape));
b2ChainShape* clone = new (mem) b2ChainShape;
clone->CreateChain(m_vertices, m_count, m_prevVertex, m_nextVertex);
return clone;
}
int32 b2ChainShape::GetChildCount() const
{
// edge count = vertex count - 1
return m_count - 1;
}
void b2ChainShape::GetChildEdge(b2EdgeShape* edge, int32 index) const
{
b2Assert(0 <= index && index < m_count - 1);
edge->m_type = b2Shape::e_edge;
edge->m_radius = m_radius;
edge->m_vertex1 = m_vertices[index + 0];
edge->m_vertex2 = m_vertices[index + 1];
edge->m_oneSided = true;
if (index > 0)
{
edge->m_vertex0 = m_vertices[index - 1];
}
else
{
edge->m_vertex0 = m_prevVertex;
}
if (index < m_count - 2)
{
edge->m_vertex3 = m_vertices[index + 2];
}
else
{
edge->m_vertex3 = m_nextVertex;
}
}
bool b2ChainShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
{
B2_NOT_USED(xf);
B2_NOT_USED(p);
return false;
}
bool b2ChainShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& xf, int32 childIndex) const
{
b2Assert(childIndex < m_count);
b2EdgeShape edgeShape;
int32 i1 = childIndex;
int32 i2 = childIndex + 1;
if (i2 == m_count)
{
i2 = 0;
}
edgeShape.m_vertex1 = m_vertices[i1];
edgeShape.m_vertex2 = m_vertices[i2];
return edgeShape.RayCast(output, input, xf, 0);
}
void b2ChainShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
{
b2Assert(childIndex < m_count);
int32 i1 = childIndex;
int32 i2 = childIndex + 1;
if (i2 == m_count)
{
i2 = 0;
}
b2Vec2 v1 = b2Mul(xf, m_vertices[i1]);
b2Vec2 v2 = b2Mul(xf, m_vertices[i2]);
b2Vec2 lower = b2Min(v1, v2);
b2Vec2 upper = b2Max(v1, v2);
b2Vec2 r(m_radius, m_radius);
aabb->lowerBound = lower - r;
aabb->upperBound = upper + r;
}
void b2ChainShape::ComputeMass(b2MassData* massData, float density) const
{
B2_NOT_USED(density);
massData->mass = 0.0f;
massData->center.SetZero();
massData->I = 0.0f;
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_circle_shape.h"
#include "box2d/b2_block_allocator.h"
#include <new>
b2Shape* b2CircleShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2CircleShape));
b2CircleShape* clone = new (mem) b2CircleShape;
*clone = *this;
return clone;
}
int32 b2CircleShape::GetChildCount() const
{
return 1;
}
bool b2CircleShape::TestPoint(const b2Transform& transform, const b2Vec2& p) const
{
b2Vec2 center = transform.p + b2Mul(transform.q, m_p);
b2Vec2 d = p - center;
return b2Dot(d, d) <= m_radius * m_radius;
}
// Collision Detection in Interactive 3D Environments by Gino van den Bergen
// From Section 3.1.2
// x = s + a * r
// norm(x) = radius
bool b2CircleShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& transform, int32 childIndex) const
{
B2_NOT_USED(childIndex);
b2Vec2 position = transform.p + b2Mul(transform.q, m_p);
b2Vec2 s = input.p1 - position;
float b = b2Dot(s, s) - m_radius * m_radius;
// Solve quadratic equation.
b2Vec2 r = input.p2 - input.p1;
float c = b2Dot(s, r);
float rr = b2Dot(r, r);
float sigma = c * c - rr * b;
// Check for negative discriminant and short segment.
if (sigma < 0.0f || rr < b2_epsilon)
{
return false;
}
// Find the point of intersection of the line with the circle.
float a = -(c + b2Sqrt(sigma));
// Is the intersection point on the segment?
if (0.0f <= a && a <= input.maxFraction * rr)
{
a /= rr;
output->fraction = a;
output->normal = s + a * r;
output->normal.Normalize();
return true;
}
return false;
}
void b2CircleShape::ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const
{
B2_NOT_USED(childIndex);
b2Vec2 p = transform.p + b2Mul(transform.q, m_p);
aabb->lowerBound.Set(p.x - m_radius, p.y - m_radius);
aabb->upperBound.Set(p.x + m_radius, p.y + m_radius);
}
void b2CircleShape::ComputeMass(b2MassData* massData, float density) const
{
massData->mass = density * b2_pi * m_radius * m_radius;
massData->center = m_p;
// inertia about the local origin
massData->I = massData->mass * (0.5f * m_radius * m_radius + b2Dot(m_p, m_p));
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_collision.h"
#include "box2d/b2_circle_shape.h"
#include "box2d/b2_polygon_shape.h"
void b2CollideCircles(
b2Manifold* manifold,
const b2CircleShape* circleA, const b2Transform& xfA,
const b2CircleShape* circleB, const b2Transform& xfB)
{
manifold->pointCount = 0;
b2Vec2 pA = b2Mul(xfA, circleA->m_p);
b2Vec2 pB = b2Mul(xfB, circleB->m_p);
b2Vec2 d = pB - pA;
float distSqr = b2Dot(d, d);
float rA = circleA->m_radius, rB = circleB->m_radius;
float radius = rA + rB;
if (distSqr > radius * radius)
{
return;
}
manifold->type = b2Manifold::e_circles;
manifold->localPoint = circleA->m_p;
manifold->localNormal.SetZero();
manifold->pointCount = 1;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
void b2CollidePolygonAndCircle(
b2Manifold* manifold,
const b2PolygonShape* polygonA, const b2Transform& xfA,
const b2CircleShape* circleB, const b2Transform& xfB)
{
manifold->pointCount = 0;
// Compute circle position in the frame of the polygon.
b2Vec2 c = b2Mul(xfB, circleB->m_p);
b2Vec2 cLocal = b2MulT(xfA, c);
// Find the min separating edge.
int32 normalIndex = 0;
float separation = -b2_maxFloat;
float radius = polygonA->m_radius + circleB->m_radius;
int32 vertexCount = polygonA->m_count;
const b2Vec2* vertices = polygonA->m_vertices;
const b2Vec2* normals = polygonA->m_normals;
for (int32 i = 0; i < vertexCount; ++i)
{
float s = b2Dot(normals[i], cLocal - vertices[i]);
if (s > radius)
{
// Early out.
return;
}
if (s > separation)
{
separation = s;
normalIndex = i;
}
}
// Vertices that subtend the incident face.
int32 vertIndex1 = normalIndex;
int32 vertIndex2 = vertIndex1 + 1 < vertexCount ? vertIndex1 + 1 : 0;
b2Vec2 v1 = vertices[vertIndex1];
b2Vec2 v2 = vertices[vertIndex2];
// If the center is inside the polygon ...
if (separation < b2_epsilon)
{
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = normals[normalIndex];
manifold->localPoint = 0.5f * (v1 + v2);
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
return;
}
// Compute barycentric coordinates
float u1 = b2Dot(cLocal - v1, v2 - v1);
float u2 = b2Dot(cLocal - v2, v1 - v2);
if (u1 <= 0.0f)
{
if (b2DistanceSquared(cLocal, v1) > radius * radius)
{
return;
}
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = cLocal - v1;
manifold->localNormal.Normalize();
manifold->localPoint = v1;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
else if (u2 <= 0.0f)
{
if (b2DistanceSquared(cLocal, v2) > radius * radius)
{
return;
}
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = cLocal - v2;
manifold->localNormal.Normalize();
manifold->localPoint = v2;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
else
{
b2Vec2 faceCenter = 0.5f * (v1 + v2);
float s = b2Dot(cLocal - faceCenter, normals[vertIndex1]);
if (s > radius)
{
return;
}
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = normals[vertIndex1];
manifold->localPoint = faceCenter;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_collision.h"
#include "box2d/b2_circle_shape.h"
#include "box2d/b2_edge_shape.h"
#include "box2d/b2_polygon_shape.h"
// Compute contact points for edge versus circle.
// This accounts for edge connectivity.
void b2CollideEdgeAndCircle(b2Manifold* manifold,
const b2EdgeShape* edgeA, const b2Transform& xfA,
const b2CircleShape* circleB, const b2Transform& xfB)
{
manifold->pointCount = 0;
// Compute circle in frame of edge
b2Vec2 Q = b2MulT(xfA, b2Mul(xfB, circleB->m_p));
b2Vec2 A = edgeA->m_vertex1, B = edgeA->m_vertex2;
b2Vec2 e = B - A;
// Normal points to the right for a CCW winding
b2Vec2 n(e.y, -e.x);
float offset = b2Dot(n, Q - A);
bool oneSided = edgeA->m_oneSided;
if (oneSided && offset < 0.0f)
{
return;
}
// Barycentric coordinates
float u = b2Dot(e, B - Q);
float v = b2Dot(e, Q - A);
float radius = edgeA->m_radius + circleB->m_radius;
b2ContactFeature cf;
cf.indexB = 0;
cf.typeB = b2ContactFeature::e_vertex;
// Region A
if (v <= 0.0f)
{
b2Vec2 P = A;
b2Vec2 d = Q - P;
float dd = b2Dot(d, d);
if (dd > radius * radius)
{
return;
}
// Is there an edge connected to A?
if (edgeA->m_oneSided)
{
b2Vec2 A1 = edgeA->m_vertex0;
b2Vec2 B1 = A;
b2Vec2 e1 = B1 - A1;
float u1 = b2Dot(e1, B1 - Q);
// Is the circle in Region AB of the previous edge?
if (u1 > 0.0f)
{
return;
}
}
cf.indexA = 0;
cf.typeA = b2ContactFeature::e_vertex;
manifold->pointCount = 1;
manifold->type = b2Manifold::e_circles;
manifold->localNormal.SetZero();
manifold->localPoint = P;
manifold->points[0].id.key = 0;
manifold->points[0].id.cf = cf;
manifold->points[0].localPoint = circleB->m_p;
return;
}
// Region B
if (u <= 0.0f)
{
b2Vec2 P = B;
b2Vec2 d = Q - P;
float dd = b2Dot(d, d);
if (dd > radius * radius)
{
return;
}
// Is there an edge connected to B?
if (edgeA->m_oneSided)
{
b2Vec2 B2 = edgeA->m_vertex3;
b2Vec2 A2 = B;
b2Vec2 e2 = B2 - A2;
float v2 = b2Dot(e2, Q - A2);
// Is the circle in Region AB of the next edge?
if (v2 > 0.0f)
{
return;
}
}
cf.indexA = 1;
cf.typeA = b2ContactFeature::e_vertex;
manifold->pointCount = 1;
manifold->type = b2Manifold::e_circles;
manifold->localNormal.SetZero();
manifold->localPoint = P;
manifold->points[0].id.key = 0;
manifold->points[0].id.cf = cf;
manifold->points[0].localPoint = circleB->m_p;
return;
}
// Region AB
float den = b2Dot(e, e);
b2Assert(den > 0.0f);
b2Vec2 P = (1.0f / den) * (u * A + v * B);
b2Vec2 d = Q - P;
float dd = b2Dot(d, d);
if (dd > radius * radius)
{
return;
}
if (offset < 0.0f)
{
n.Set(-n.x, -n.y);
}
n.Normalize();
cf.indexA = 0;
cf.typeA = b2ContactFeature::e_face;
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = n;
manifold->localPoint = A;
manifold->points[0].id.key = 0;
manifold->points[0].id.cf = cf;
manifold->points[0].localPoint = circleB->m_p;
}
// This structure is used to keep track of the best separating axis.
struct b2EPAxis
{
enum Type
{
e_unknown,
e_edgeA,
e_edgeB
};
b2Vec2 normal;
Type type;
int32 index;
float separation;
};
// This holds polygon B expressed in frame A.
struct b2TempPolygon
{
b2Vec2 vertices[b2_maxPolygonVertices];
b2Vec2 normals[b2_maxPolygonVertices];
int32 count;
};
// Reference face used for clipping
struct b2ReferenceFace
{
int32 i1, i2;
b2Vec2 v1, v2;
b2Vec2 normal;
b2Vec2 sideNormal1;
float sideOffset1;
b2Vec2 sideNormal2;
float sideOffset2;
};
static b2EPAxis b2ComputeEdgeSeparation(const b2TempPolygon& polygonB, const b2Vec2& v1, const b2Vec2& normal1)
{
b2EPAxis axis;
axis.type = b2EPAxis::e_edgeA;
axis.index = -1;
axis.separation = -FLT_MAX;
axis.normal.SetZero();
b2Vec2 axes[2] = { normal1, -normal1 };
// Find axis with least overlap (min-max problem)
for (int32 j = 0; j < 2; ++j)
{
float sj = FLT_MAX;
// Find deepest polygon vertex along axis j
for (int32 i = 0; i < polygonB.count; ++i)
{
float si = b2Dot(axes[j], polygonB.vertices[i] - v1);
if (si < sj)
{
sj = si;
}
}
if (sj > axis.separation)
{
axis.index = j;
axis.separation = sj;
axis.normal = axes[j];
}
}
return axis;
}
static b2EPAxis b2ComputePolygonSeparation(const b2TempPolygon& polygonB, const b2Vec2& v1, const b2Vec2& v2)
{
b2EPAxis axis;
axis.type = b2EPAxis::e_unknown;
axis.index = -1;
axis.separation = -FLT_MAX;
axis.normal.SetZero();
for (int32 i = 0; i < polygonB.count; ++i)
{
b2Vec2 n = -polygonB.normals[i];
float s1 = b2Dot(n, polygonB.vertices[i] - v1);
float s2 = b2Dot(n, polygonB.vertices[i] - v2);
float s = b2Min(s1, s2);
if (s > axis.separation)
{
axis.type = b2EPAxis::e_edgeB;
axis.index = i;
axis.separation = s;
axis.normal = n;
}
}
return axis;
}
void b2CollideEdgeAndPolygon(b2Manifold* manifold,
const b2EdgeShape* edgeA, const b2Transform& xfA,
const b2PolygonShape* polygonB, const b2Transform& xfB)
{
manifold->pointCount = 0;
b2Transform xf = b2MulT(xfA, xfB);
b2Vec2 centroidB = b2Mul(xf, polygonB->m_centroid);
b2Vec2 v1 = edgeA->m_vertex1;
b2Vec2 v2 = edgeA->m_vertex2;
b2Vec2 edge1 = v2 - v1;
edge1.Normalize();
// Normal points to the right for a CCW winding
b2Vec2 normal1(edge1.y, -edge1.x);
float offset1 = b2Dot(normal1, centroidB - v1);
bool oneSided = edgeA->m_oneSided;
if (oneSided && offset1 < 0.0f)
{
return;
}
// Get polygonB in frameA
b2TempPolygon tempPolygonB;
tempPolygonB.count = polygonB->m_count;
for (int32 i = 0; i < polygonB->m_count; ++i)
{
tempPolygonB.vertices[i] = b2Mul(xf, polygonB->m_vertices[i]);
tempPolygonB.normals[i] = b2Mul(xf.q, polygonB->m_normals[i]);
}
float radius = polygonB->m_radius + edgeA->m_radius;
b2EPAxis edgeAxis = b2ComputeEdgeSeparation(tempPolygonB, v1, normal1);
if (edgeAxis.separation > radius)
{
return;
}
b2EPAxis polygonAxis = b2ComputePolygonSeparation(tempPolygonB, v1, v2);
if (polygonAxis.separation > radius)
{
return;
}
// Use hysteresis for jitter reduction.
const float k_relativeTol = 0.98f;
const float k_absoluteTol = 0.001f;
b2EPAxis primaryAxis;
if (polygonAxis.separation - radius > k_relativeTol * (edgeAxis.separation - radius) + k_absoluteTol)
{
primaryAxis = polygonAxis;
}
else
{
primaryAxis = edgeAxis;
}
if (oneSided)
{
// Smooth collision
// See https://box2d.org/posts/2020/06/ghost-collisions/
b2Vec2 edge0 = v1 - edgeA->m_vertex0;
edge0.Normalize();
b2Vec2 normal0(edge0.y, -edge0.x);
bool convex1 = b2Cross(edge0, edge1) >= 0.0f;
b2Vec2 edge2 = edgeA->m_vertex3 - v2;
edge2.Normalize();
b2Vec2 normal2(edge2.y, -edge2.x);
bool convex2 = b2Cross(edge1, edge2) >= 0.0f;
const float sinTol = 0.1f;
bool side1 = b2Dot(primaryAxis.normal, edge1) <= 0.0f;
// Check Gauss Map
if (side1)
{
if (convex1)
{
if (b2Cross(primaryAxis.normal, normal0) > sinTol)
{
// Skip region
return;
}
// Admit region
}
else
{
// Snap region
primaryAxis = edgeAxis;
}
}
else
{
if (convex2)
{
if (b2Cross(normal2, primaryAxis.normal) > sinTol)
{
// Skip region
return;
}
// Admit region
}
else
{
// Snap region
primaryAxis = edgeAxis;
}
}
}
b2ClipVertex clipPoints[2];
b2ReferenceFace ref;
if (primaryAxis.type == b2EPAxis::e_edgeA)
{
manifold->type = b2Manifold::e_faceA;
// Search for the polygon normal that is most anti-parallel to the edge normal.
int32 bestIndex = 0;
float bestValue = b2Dot(primaryAxis.normal, tempPolygonB.normals[0]);
for (int32 i = 1; i < tempPolygonB.count; ++i)
{
float value = b2Dot(primaryAxis.normal, tempPolygonB.normals[i]);
if (value < bestValue)
{
bestValue = value;
bestIndex = i;
}
}
int32 i1 = bestIndex;
int32 i2 = i1 + 1 < tempPolygonB.count ? i1 + 1 : 0;
clipPoints[0].v = tempPolygonB.vertices[i1];
clipPoints[0].id.cf.indexA = 0;
clipPoints[0].id.cf.indexB = static_cast<uint8>(i1);
clipPoints[0].id.cf.typeA = b2ContactFeature::e_face;
clipPoints[0].id.cf.typeB = b2ContactFeature::e_vertex;
clipPoints[1].v = tempPolygonB.vertices[i2];
clipPoints[1].id.cf.indexA = 0;
clipPoints[1].id.cf.indexB = static_cast<uint8>(i2);
clipPoints[1].id.cf.typeA = b2ContactFeature::e_face;
clipPoints[1].id.cf.typeB = b2ContactFeature::e_vertex;
ref.i1 = 0;
ref.i2 = 1;
ref.v1 = v1;
ref.v2 = v2;
ref.normal = primaryAxis.normal;
ref.sideNormal1 = -edge1;
ref.sideNormal2 = edge1;
}
else
{
manifold->type = b2Manifold::e_faceB;
clipPoints[0].v = v2;
clipPoints[0].id.cf.indexA = 1;
clipPoints[0].id.cf.indexB = static_cast<uint8>(primaryAxis.index);
clipPoints[0].id.cf.typeA = b2ContactFeature::e_vertex;
clipPoints[0].id.cf.typeB = b2ContactFeature::e_face;
clipPoints[1].v = v1;
clipPoints[1].id.cf.indexA = 0;
clipPoints[1].id.cf.indexB = static_cast<uint8>(primaryAxis.index);
clipPoints[1].id.cf.typeA = b2ContactFeature::e_vertex;
clipPoints[1].id.cf.typeB = b2ContactFeature::e_face;
ref.i1 = primaryAxis.index;
ref.i2 = ref.i1 + 1 < tempPolygonB.count ? ref.i1 + 1 : 0;
ref.v1 = tempPolygonB.vertices[ref.i1];
ref.v2 = tempPolygonB.vertices[ref.i2];
ref.normal = tempPolygonB.normals[ref.i1];
// CCW winding
ref.sideNormal1.Set(ref.normal.y, -ref.normal.x);
ref.sideNormal2 = -ref.sideNormal1;
}
ref.sideOffset1 = b2Dot(ref.sideNormal1, ref.v1);
ref.sideOffset2 = b2Dot(ref.sideNormal2, ref.v2);
// Clip incident edge against reference face side planes
b2ClipVertex clipPoints1[2];
b2ClipVertex clipPoints2[2];
int32 np;
// Clip to side 1
np = b2ClipSegmentToLine(clipPoints1, clipPoints, ref.sideNormal1, ref.sideOffset1, ref.i1);
if (np < b2_maxManifoldPoints)
{
return;
}
// Clip to side 2
np = b2ClipSegmentToLine(clipPoints2, clipPoints1, ref.sideNormal2, ref.sideOffset2, ref.i2);
if (np < b2_maxManifoldPoints)
{
return;
}
// Now clipPoints2 contains the clipped points.
if (primaryAxis.type == b2EPAxis::e_edgeA)
{
manifold->localNormal = ref.normal;
manifold->localPoint = ref.v1;
}
else
{
manifold->localNormal = polygonB->m_normals[ref.i1];
manifold->localPoint = polygonB->m_vertices[ref.i1];
}
int32 pointCount = 0;
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
float separation;
separation = b2Dot(ref.normal, clipPoints2[i].v - ref.v1);
if (separation <= radius)
{
b2ManifoldPoint* cp = manifold->points + pointCount;
if (primaryAxis.type == b2EPAxis::e_edgeA)
{
cp->localPoint = b2MulT(xf, clipPoints2[i].v);
cp->id = clipPoints2[i].id;
}
else
{
cp->localPoint = clipPoints2[i].v;
cp->id.cf.typeA = clipPoints2[i].id.cf.typeB;
cp->id.cf.typeB = clipPoints2[i].id.cf.typeA;
cp->id.cf.indexA = clipPoints2[i].id.cf.indexB;
cp->id.cf.indexB = clipPoints2[i].id.cf.indexA;
}
++pointCount;
}
}
manifold->pointCount = pointCount;
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_collision.h"
#include "box2d/b2_polygon_shape.h"
// Find the max separation between poly1 and poly2 using edge normals from poly1.
static float b2FindMaxSeparation(int32* edgeIndex,
const b2PolygonShape* poly1, const b2Transform& xf1,
const b2PolygonShape* poly2, const b2Transform& xf2)
{
int32 count1 = poly1->m_count;
int32 count2 = poly2->m_count;
const b2Vec2* n1s = poly1->m_normals;
const b2Vec2* v1s = poly1->m_vertices;
const b2Vec2* v2s = poly2->m_vertices;
b2Transform xf = b2MulT(xf2, xf1);
int32 bestIndex = 0;
float maxSeparation = -b2_maxFloat;
for (int32 i = 0; i < count1; ++i)
{
// Get poly1 normal in frame2.
b2Vec2 n = b2Mul(xf.q, n1s[i]);
b2Vec2 v1 = b2Mul(xf, v1s[i]);
// Find deepest point for normal i.
float si = b2_maxFloat;
for (int32 j = 0; j < count2; ++j)
{
float sij = b2Dot(n, v2s[j] - v1);
if (sij < si)
{
si = sij;
}
}
if (si > maxSeparation)
{
maxSeparation = si;
bestIndex = i;
}
}
*edgeIndex = bestIndex;
return maxSeparation;
}
static void b2FindIncidentEdge(b2ClipVertex c[2],
const b2PolygonShape* poly1, const b2Transform& xf1, int32 edge1,
const b2PolygonShape* poly2, const b2Transform& xf2)
{
const b2Vec2* normals1 = poly1->m_normals;
int32 count2 = poly2->m_count;
const b2Vec2* vertices2 = poly2->m_vertices;
const b2Vec2* normals2 = poly2->m_normals;
b2Assert(0 <= edge1 && edge1 < poly1->m_count);
// Get the normal of the reference edge in poly2's frame.
b2Vec2 normal1 = b2MulT(xf2.q, b2Mul(xf1.q, normals1[edge1]));
// Find the incident edge on poly2.
int32 index = 0;
float minDot = b2_maxFloat;
for (int32 i = 0; i < count2; ++i)
{
float dot = b2Dot(normal1, normals2[i]);
if (dot < minDot)
{
minDot = dot;
index = i;
}
}
// Build the clip vertices for the incident edge.
int32 i1 = index;
int32 i2 = i1 + 1 < count2 ? i1 + 1 : 0;
c[0].v = b2Mul(xf2, vertices2[i1]);
c[0].id.cf.indexA = (uint8)edge1;
c[0].id.cf.indexB = (uint8)i1;
c[0].id.cf.typeA = b2ContactFeature::e_face;
c[0].id.cf.typeB = b2ContactFeature::e_vertex;
c[1].v = b2Mul(xf2, vertices2[i2]);
c[1].id.cf.indexA = (uint8)edge1;
c[1].id.cf.indexB = (uint8)i2;
c[1].id.cf.typeA = b2ContactFeature::e_face;
c[1].id.cf.typeB = b2ContactFeature::e_vertex;
}
// Find edge normal of max separation on A - return if separating axis is found
// Find edge normal of max separation on B - return if separation axis is found
// Choose reference edge as min(minA, minB)
// Find incident edge
// Clip
// The normal points from 1 to 2
void b2CollidePolygons(b2Manifold* manifold,
const b2PolygonShape* polyA, const b2Transform& xfA,
const b2PolygonShape* polyB, const b2Transform& xfB)
{
manifold->pointCount = 0;
float totalRadius = polyA->m_radius + polyB->m_radius;
int32 edgeA = 0;
float separationA = b2FindMaxSeparation(&edgeA, polyA, xfA, polyB, xfB);
if (separationA > totalRadius)
return;
int32 edgeB = 0;
float separationB = b2FindMaxSeparation(&edgeB, polyB, xfB, polyA, xfA);
if (separationB > totalRadius)
return;
const b2PolygonShape* poly1; // reference polygon
const b2PolygonShape* poly2; // incident polygon
b2Transform xf1, xf2;
int32 edge1; // reference edge
uint8 flip;
const float k_tol = 0.1f * b2_linearSlop;
if (separationB > separationA + k_tol)
{
poly1 = polyB;
poly2 = polyA;
xf1 = xfB;
xf2 = xfA;
edge1 = edgeB;
manifold->type = b2Manifold::e_faceB;
flip = 1;
}
else
{
poly1 = polyA;
poly2 = polyB;
xf1 = xfA;
xf2 = xfB;
edge1 = edgeA;
manifold->type = b2Manifold::e_faceA;
flip = 0;
}
b2ClipVertex incidentEdge[2];
b2FindIncidentEdge(incidentEdge, poly1, xf1, edge1, poly2, xf2);
int32 count1 = poly1->m_count;
const b2Vec2* vertices1 = poly1->m_vertices;
int32 iv1 = edge1;
int32 iv2 = edge1 + 1 < count1 ? edge1 + 1 : 0;
b2Vec2 v11 = vertices1[iv1];
b2Vec2 v12 = vertices1[iv2];
b2Vec2 localTangent = v12 - v11;
localTangent.Normalize();
b2Vec2 localNormal = b2Cross(localTangent, 1.0f);
b2Vec2 planePoint = 0.5f * (v11 + v12);
b2Vec2 tangent = b2Mul(xf1.q, localTangent);
b2Vec2 normal = b2Cross(tangent, 1.0f);
v11 = b2Mul(xf1, v11);
v12 = b2Mul(xf1, v12);
// Face offset.
float frontOffset = b2Dot(normal, v11);
// Side offsets, extended by polytope skin thickness.
float sideOffset1 = -b2Dot(tangent, v11) + totalRadius;
float sideOffset2 = b2Dot(tangent, v12) + totalRadius;
// Clip incident edge against extruded edge1 side edges.
b2ClipVertex clipPoints1[2];
b2ClipVertex clipPoints2[2];
int np;
// Clip to box side 1
np = b2ClipSegmentToLine(clipPoints1, incidentEdge, -tangent, sideOffset1, iv1);
if (np < 2)
return;
// Clip to negative box side 1
np = b2ClipSegmentToLine(clipPoints2, clipPoints1, tangent, sideOffset2, iv2);
if (np < 2)
{
return;
}
// Now clipPoints2 contains the clipped points.
manifold->localNormal = localNormal;
manifold->localPoint = planePoint;
int32 pointCount = 0;
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
float separation = b2Dot(normal, clipPoints2[i].v) - frontOffset;
if (separation <= totalRadius)
{
b2ManifoldPoint* cp = manifold->points + pointCount;
cp->localPoint = b2MulT(xf2, clipPoints2[i].v);
cp->id = clipPoints2[i].id;
if (flip)
{
// Swap features
b2ContactFeature cf = cp->id.cf;
cp->id.cf.indexA = cf.indexB;
cp->id.cf.indexB = cf.indexA;
cp->id.cf.typeA = cf.typeB;
cp->id.cf.typeB = cf.typeA;
}
++pointCount;
}
}
manifold->pointCount = pointCount;
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_collision.h"
#include "box2d/b2_distance.h"
void b2WorldManifold::Initialize(const b2Manifold* manifold,
const b2Transform& xfA, float radiusA,
const b2Transform& xfB, float radiusB)
{
if (manifold->pointCount == 0)
{
return;
}
switch (manifold->type)
{
case b2Manifold::e_circles:
{
normal.Set(1.0f, 0.0f);
b2Vec2 pointA = b2Mul(xfA, manifold->localPoint);
b2Vec2 pointB = b2Mul(xfB, manifold->points[0].localPoint);
if (b2DistanceSquared(pointA, pointB) > b2_epsilon * b2_epsilon)
{
normal = pointB - pointA;
normal.Normalize();
}
b2Vec2 cA = pointA + radiusA * normal;
b2Vec2 cB = pointB - radiusB * normal;
points[0] = 0.5f * (cA + cB);
separations[0] = b2Dot(cB - cA, normal);
}
break;
case b2Manifold::e_faceA:
{
normal = b2Mul(xfA.q, manifold->localNormal);
b2Vec2 planePoint = b2Mul(xfA, manifold->localPoint);
for (int32 i = 0; i < manifold->pointCount; ++i)
{
b2Vec2 clipPoint = b2Mul(xfB, manifold->points[i].localPoint);
b2Vec2 cA = clipPoint + (radiusA - b2Dot(clipPoint - planePoint, normal)) * normal;
b2Vec2 cB = clipPoint - radiusB * normal;
points[i] = 0.5f * (cA + cB);
separations[i] = b2Dot(cB - cA, normal);
}
}
break;
case b2Manifold::e_faceB:
{
normal = b2Mul(xfB.q, manifold->localNormal);
b2Vec2 planePoint = b2Mul(xfB, manifold->localPoint);
for (int32 i = 0; i < manifold->pointCount; ++i)
{
b2Vec2 clipPoint = b2Mul(xfA, manifold->points[i].localPoint);
b2Vec2 cB = clipPoint + (radiusB - b2Dot(clipPoint - planePoint, normal)) * normal;
b2Vec2 cA = clipPoint - radiusA * normal;
points[i] = 0.5f * (cA + cB);
separations[i] = b2Dot(cA - cB, normal);
}
// Ensure normal points from A to B.
normal = -normal;
}
break;
}
}
void b2GetPointStates(b2PointState state1[b2_maxManifoldPoints], b2PointState state2[b2_maxManifoldPoints],
const b2Manifold* manifold1, const b2Manifold* manifold2)
{
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
state1[i] = b2_nullState;
state2[i] = b2_nullState;
}
// Detect persists and removes.
for (int32 i = 0; i < manifold1->pointCount; ++i)
{
b2ContactID id = manifold1->points[i].id;
state1[i] = b2_removeState;
for (int32 j = 0; j < manifold2->pointCount; ++j)
{
if (manifold2->points[j].id.key == id.key)
{
state1[i] = b2_persistState;
break;
}
}
}
// Detect persists and adds.
for (int32 i = 0; i < manifold2->pointCount; ++i)
{
b2ContactID id = manifold2->points[i].id;
state2[i] = b2_addState;
for (int32 j = 0; j < manifold1->pointCount; ++j)
{
if (manifold1->points[j].id.key == id.key)
{
state2[i] = b2_persistState;
break;
}
}
}
}
// From Real-time Collision Detection, p179.
bool b2AABB::RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const
{
float tmin = -b2_maxFloat;
float tmax = b2_maxFloat;
b2Vec2 p = input.p1;
b2Vec2 d = input.p2 - input.p1;
b2Vec2 absD = b2Abs(d);
b2Vec2 normal;
for (int32 i = 0; i < 2; ++i)
{
if (absD(i) < b2_epsilon)
{
// Parallel.
if (p(i) < lowerBound(i) || upperBound(i) < p(i))
{
return false;
}
}
else
{
float inv_d = 1.0f / d(i);
float t1 = (lowerBound(i) - p(i)) * inv_d;
float t2 = (upperBound(i) - p(i)) * inv_d;
// Sign of the normal vector.
float s = -1.0f;
if (t1 > t2)
{
b2Swap(t1, t2);
s = 1.0f;
}
// Push the min up
if (t1 > tmin)
{
normal.SetZero();
normal(i) = s;
tmin = t1;
}
// Pull the max down
tmax = b2Min(tmax, t2);
if (tmin > tmax)
{
return false;
}
}
}
// Does the ray start inside the box?
// Does the ray intersect beyond the max fraction?
if (tmin < 0.0f || input.maxFraction < tmin)
{
return false;
}
// Intersection.
output->fraction = tmin;
output->normal = normal;
return true;
}
// Sutherland-Hodgman clipping.
int32 b2ClipSegmentToLine(b2ClipVertex vOut[2], const b2ClipVertex vIn[2],
const b2Vec2& normal, float offset, int32 vertexIndexA)
{
// Start with no output points
int32 count = 0;
// Calculate the distance of end points to the line
float distance0 = b2Dot(normal, vIn[0].v) - offset;
float distance1 = b2Dot(normal, vIn[1].v) - offset;
// If the points are behind the plane
if (distance0 <= 0.0f) vOut[count++] = vIn[0];
if (distance1 <= 0.0f) vOut[count++] = vIn[1];
// If the points are on different sides of the plane
if (distance0 * distance1 < 0.0f)
{
// Find intersection point of edge and plane
float interp = distance0 / (distance0 - distance1);
vOut[count].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
// VertexA is hitting edgeB.
vOut[count].id.cf.indexA = static_cast<uint8>(vertexIndexA);
vOut[count].id.cf.indexB = vIn[0].id.cf.indexB;
vOut[count].id.cf.typeA = b2ContactFeature::e_vertex;
vOut[count].id.cf.typeB = b2ContactFeature::e_face;
++count;
b2Assert(count == 2);
}
return count;
}
bool b2TestOverlap( const b2Shape* shapeA, int32 indexA,
const b2Shape* shapeB, int32 indexB,
const b2Transform& xfA, const b2Transform& xfB)
{
b2DistanceInput input;
input.proxyA.Set(shapeA, indexA);
input.proxyB.Set(shapeB, indexB);
input.transformA = xfA;
input.transformB = xfB;
input.useRadii = true;
b2SimplexCache cache;
cache.count = 0;
b2DistanceOutput output;
b2Distance(&output, &cache, &input);
return output.distance < 10.0f * b2_epsilon;
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_circle_shape.h"
#include "box2d/b2_distance.h"
#include "box2d/b2_edge_shape.h"
#include "box2d/b2_chain_shape.h"
#include "box2d/b2_polygon_shape.h"
// GJK using Voronoi regions (Christer Ericson) and Barycentric coordinates.
B2_API int32 b2_gjkCalls, b2_gjkIters, b2_gjkMaxIters;
void b2DistanceProxy::Set(const b2Shape* shape, int32 index)
{
switch (shape->GetType())
{
case b2Shape::e_circle:
{
const b2CircleShape* circle = static_cast<const b2CircleShape*>(shape);
m_vertices = &circle->m_p;
m_count = 1;
m_radius = circle->m_radius;
}
break;
case b2Shape::e_polygon:
{
const b2PolygonShape* polygon = static_cast<const b2PolygonShape*>(shape);
m_vertices = polygon->m_vertices;
m_count = polygon->m_count;
m_radius = polygon->m_radius;
}
break;
case b2Shape::e_chain:
{
const b2ChainShape* chain = static_cast<const b2ChainShape*>(shape);
b2Assert(0 <= index && index < chain->m_count);
m_buffer[0] = chain->m_vertices[index];
if (index + 1 < chain->m_count)
{
m_buffer[1] = chain->m_vertices[index + 1];
}
else
{
m_buffer[1] = chain->m_vertices[0];
}
m_vertices = m_buffer;
m_count = 2;
m_radius = chain->m_radius;
}
break;
case b2Shape::e_edge:
{
const b2EdgeShape* edge = static_cast<const b2EdgeShape*>(shape);
m_vertices = &edge->m_vertex1;
m_count = 2;
m_radius = edge->m_radius;
}
break;
default:
b2Assert(false);
}
}
void b2DistanceProxy::Set(const b2Vec2* vertices, int32 count, float radius)
{
m_vertices = vertices;
m_count = count;
m_radius = radius;
}
struct b2SimplexVertex
{
b2Vec2 wA; // support point in proxyA
b2Vec2 wB; // support point in proxyB
b2Vec2 w; // wB - wA
float a; // barycentric coordinate for closest point
int32 indexA; // wA index
int32 indexB; // wB index
};
struct b2Simplex
{
void ReadCache( const b2SimplexCache* cache,
const b2DistanceProxy* proxyA, const b2Transform& transformA,
const b2DistanceProxy* proxyB, const b2Transform& transformB)
{
b2Assert(cache->count <= 3);
// Copy data from cache.
m_count = cache->count;
b2SimplexVertex* vertices = &m_v1;
for (int32 i = 0; i < m_count; ++i)
{
b2SimplexVertex* v = vertices + i;
v->indexA = cache->indexA[i];
v->indexB = cache->indexB[i];
b2Vec2 wALocal = proxyA->GetVertex(v->indexA);
b2Vec2 wBLocal = proxyB->GetVertex(v->indexB);
v->wA = b2Mul(transformA, wALocal);
v->wB = b2Mul(transformB, wBLocal);
v->w = v->wB - v->wA;
v->a = 0.0f;
}
// Compute the new simplex metric, if it is substantially different than
// old metric then flush the simplex.
if (m_count > 1)
{
float metric1 = cache->metric;
float metric2 = GetMetric();
if (metric2 < 0.5f * metric1 || 2.0f * metric1 < metric2 || metric2 < b2_epsilon)
{
// Reset the simplex.
m_count = 0;
}
}
// If the cache is empty or invalid ...
if (m_count == 0)
{
b2SimplexVertex* v = vertices + 0;
v->indexA = 0;
v->indexB = 0;
b2Vec2 wALocal = proxyA->GetVertex(0);
b2Vec2 wBLocal = proxyB->GetVertex(0);
v->wA = b2Mul(transformA, wALocal);
v->wB = b2Mul(transformB, wBLocal);
v->w = v->wB - v->wA;
v->a = 1.0f;
m_count = 1;
}
}
void WriteCache(b2SimplexCache* cache) const
{
cache->metric = GetMetric();
cache->count = uint16(m_count);
const b2SimplexVertex* vertices = &m_v1;
for (int32 i = 0; i < m_count; ++i)
{
cache->indexA[i] = uint8(vertices[i].indexA);
cache->indexB[i] = uint8(vertices[i].indexB);
}
}
b2Vec2 GetSearchDirection() const
{
switch (m_count)
{
case 1:
return -m_v1.w;
case 2:
{
b2Vec2 e12 = m_v2.w - m_v1.w;
float sgn = b2Cross(e12, -m_v1.w);
if (sgn > 0.0f)
{
// Origin is left of e12.
return b2Cross(1.0f, e12);
}
else
{
// Origin is right of e12.
return b2Cross(e12, 1.0f);
}
}
default:
b2Assert(false);
return b2Vec2_zero;
}
}
b2Vec2 GetClosestPoint() const
{
switch (m_count)
{
case 0:
b2Assert(false);
return b2Vec2_zero;
case 1:
return m_v1.w;
case 2:
return m_v1.a * m_v1.w + m_v2.a * m_v2.w;
case 3:
return b2Vec2_zero;
default:
b2Assert(false);
return b2Vec2_zero;
}
}
void GetWitnessPoints(b2Vec2* pA, b2Vec2* pB) const
{
switch (m_count)
{
case 0:
b2Assert(false);
break;
case 1:
*pA = m_v1.wA;
*pB = m_v1.wB;
break;
case 2:
*pA = m_v1.a * m_v1.wA + m_v2.a * m_v2.wA;
*pB = m_v1.a * m_v1.wB + m_v2.a * m_v2.wB;
break;
case 3:
*pA = m_v1.a * m_v1.wA + m_v2.a * m_v2.wA + m_v3.a * m_v3.wA;
*pB = *pA;
break;
default:
b2Assert(false);
break;
}
}
float GetMetric() const
{
switch (m_count)
{
case 0:
b2Assert(false);
return 0.0f;
case 1:
return 0.0f;
case 2:
return b2Distance(m_v1.w, m_v2.w);
case 3:
return b2Cross(m_v2.w - m_v1.w, m_v3.w - m_v1.w);
default:
b2Assert(false);
return 0.0f;
}
}
void Solve2();
void Solve3();
b2SimplexVertex m_v1, m_v2, m_v3;
int32 m_count;
};
// Solve a line segment using barycentric coordinates.
//
// p = a1 * w1 + a2 * w2
// a1 + a2 = 1
//
// The vector from the origin to the closest point on the line is
// perpendicular to the line.
// e12 = w2 - w1
// dot(p, e) = 0
// a1 * dot(w1, e) + a2 * dot(w2, e) = 0
//
// 2-by-2 linear system
// [1 1 ][a1] = [1]
// [w1.e12 w2.e12][a2] = [0]
//
// Define
// d12_1 = dot(w2, e12)
// d12_2 = -dot(w1, e12)
// d12 = d12_1 + d12_2
//
// Solution
// a1 = d12_1 / d12
// a2 = d12_2 / d12
void b2Simplex::Solve2()
{
b2Vec2 w1 = m_v1.w;
b2Vec2 w2 = m_v2.w;
b2Vec2 e12 = w2 - w1;
// w1 region
float d12_2 = -b2Dot(w1, e12);
if (d12_2 <= 0.0f)
{
// a2 <= 0, so we clamp it to 0
m_v1.a = 1.0f;
m_count = 1;
return;
}
// w2 region
float d12_1 = b2Dot(w2, e12);
if (d12_1 <= 0.0f)
{
// a1 <= 0, so we clamp it to 0
m_v2.a = 1.0f;
m_count = 1;
m_v1 = m_v2;
return;
}
// Must be in e12 region.
float inv_d12 = 1.0f / (d12_1 + d12_2);
m_v1.a = d12_1 * inv_d12;
m_v2.a = d12_2 * inv_d12;
m_count = 2;
}
// Possible regions:
// - points[2]
// - edge points[0]-points[2]
// - edge points[1]-points[2]
// - inside the triangle
void b2Simplex::Solve3()
{
b2Vec2 w1 = m_v1.w;
b2Vec2 w2 = m_v2.w;
b2Vec2 w3 = m_v3.w;
// Edge12
// [1 1 ][a1] = [1]
// [w1.e12 w2.e12][a2] = [0]
// a3 = 0
b2Vec2 e12 = w2 - w1;
float w1e12 = b2Dot(w1, e12);
float w2e12 = b2Dot(w2, e12);
float d12_1 = w2e12;
float d12_2 = -w1e12;
// Edge13
// [1 1 ][a1] = [1]
// [w1.e13 w3.e13][a3] = [0]
// a2 = 0
b2Vec2 e13 = w3 - w1;
float w1e13 = b2Dot(w1, e13);
float w3e13 = b2Dot(w3, e13);
float d13_1 = w3e13;
float d13_2 = -w1e13;
// Edge23
// [1 1 ][a2] = [1]
// [w2.e23 w3.e23][a3] = [0]
// a1 = 0
b2Vec2 e23 = w3 - w2;
float w2e23 = b2Dot(w2, e23);
float w3e23 = b2Dot(w3, e23);
float d23_1 = w3e23;
float d23_2 = -w2e23;
// Triangle123
float n123 = b2Cross(e12, e13);
float d123_1 = n123 * b2Cross(w2, w3);
float d123_2 = n123 * b2Cross(w3, w1);
float d123_3 = n123 * b2Cross(w1, w2);
// w1 region
if (d12_2 <= 0.0f && d13_2 <= 0.0f)
{
m_v1.a = 1.0f;
m_count = 1;
return;
}
// e12
if (d12_1 > 0.0f && d12_2 > 0.0f && d123_3 <= 0.0f)
{
float inv_d12 = 1.0f / (d12_1 + d12_2);
m_v1.a = d12_1 * inv_d12;
m_v2.a = d12_2 * inv_d12;
m_count = 2;
return;
}
// e13
if (d13_1 > 0.0f && d13_2 > 0.0f && d123_2 <= 0.0f)
{
float inv_d13 = 1.0f / (d13_1 + d13_2);
m_v1.a = d13_1 * inv_d13;
m_v3.a = d13_2 * inv_d13;
m_count = 2;
m_v2 = m_v3;
return;
}
// w2 region
if (d12_1 <= 0.0f && d23_2 <= 0.0f)
{
m_v2.a = 1.0f;
m_count = 1;
m_v1 = m_v2;
return;
}
// w3 region
if (d13_1 <= 0.0f && d23_1 <= 0.0f)
{
m_v3.a = 1.0f;
m_count = 1;
m_v1 = m_v3;
return;
}
// e23
if (d23_1 > 0.0f && d23_2 > 0.0f && d123_1 <= 0.0f)
{
float inv_d23 = 1.0f / (d23_1 + d23_2);
m_v2.a = d23_1 * inv_d23;
m_v3.a = d23_2 * inv_d23;
m_count = 2;
m_v1 = m_v3;
return;
}
// Must be in triangle123
float inv_d123 = 1.0f / (d123_1 + d123_2 + d123_3);
m_v1.a = d123_1 * inv_d123;
m_v2.a = d123_2 * inv_d123;
m_v3.a = d123_3 * inv_d123;
m_count = 3;
}
void b2Distance(b2DistanceOutput* output,
b2SimplexCache* cache,
const b2DistanceInput* input)
{
++b2_gjkCalls;
const b2DistanceProxy* proxyA = &input->proxyA;
const b2DistanceProxy* proxyB = &input->proxyB;
b2Transform transformA = input->transformA;
b2Transform transformB = input->transformB;
// Initialize the simplex.
b2Simplex simplex;
simplex.ReadCache(cache, proxyA, transformA, proxyB, transformB);
// Get simplex vertices as an array.
b2SimplexVertex* vertices = &simplex.m_v1;
const int32 k_maxIters = 20;
// These store the vertices of the last simplex so that we
// can check for duplicates and prevent cycling.
int32 saveA[3], saveB[3];
int32 saveCount = 0;
// Main iteration loop.
int32 iter = 0;
while (iter < k_maxIters)
{
// Copy simplex so we can identify duplicates.
saveCount = simplex.m_count;
for (int32 i = 0; i < saveCount; ++i)
{
saveA[i] = vertices[i].indexA;
saveB[i] = vertices[i].indexB;
}
switch (simplex.m_count)
{
case 1:
break;
case 2:
simplex.Solve2();
break;
case 3:
simplex.Solve3();
break;
default:
b2Assert(false);
}
// If we have 3 points, then the origin is in the corresponding triangle.
if (simplex.m_count == 3)
{
break;
}
// Get search direction.
b2Vec2 d = simplex.GetSearchDirection();
// Ensure the search direction is numerically fit.
if (d.LengthSquared() < b2_epsilon * b2_epsilon)
{
// The origin is probably contained by a line segment
// or triangle. Thus the shapes are overlapped.
// We can't return zero here even though there may be overlap.
// In case the simplex is a point, segment, or triangle it is difficult
// to determine if the origin is contained in the CSO or very close to it.
break;
}
// Compute a tentative new simplex vertex using support points.
b2SimplexVertex* vertex = vertices + simplex.m_count;
vertex->indexA = proxyA->GetSupport(b2MulT(transformA.q, -d));
vertex->wA = b2Mul(transformA, proxyA->GetVertex(vertex->indexA));
vertex->indexB = proxyB->GetSupport(b2MulT(transformB.q, d));
vertex->wB = b2Mul(transformB, proxyB->GetVertex(vertex->indexB));
vertex->w = vertex->wB - vertex->wA;
// Iteration count is equated to the number of support point calls.
++iter;
++b2_gjkIters;
// Check for duplicate support points. This is the main termination criteria.
bool duplicate = false;
for (int32 i = 0; i < saveCount; ++i)
{
if (vertex->indexA == saveA[i] && vertex->indexB == saveB[i])
{
duplicate = true;
break;
}
}
// If we found a duplicate support point we must exit to avoid cycling.
if (duplicate)
{
break;
}
// New vertex is ok and needed.
++simplex.m_count;
}
b2_gjkMaxIters = b2Max(b2_gjkMaxIters, iter);
// Prepare output.
simplex.GetWitnessPoints(&output->pointA, &output->pointB);
output->distance = b2Distance(output->pointA, output->pointB);
output->iterations = iter;
// Cache the simplex.
simplex.WriteCache(cache);
// Apply radii if requested.
if (input->useRadii)
{
float rA = proxyA->m_radius;
float rB = proxyB->m_radius;
if (output->distance > rA + rB && output->distance > b2_epsilon)
{
// Shapes are still no overlapped.
// Move the witness points to the outer surface.
output->distance -= rA + rB;
b2Vec2 normal = output->pointB - output->pointA;
normal.Normalize();
output->pointA += rA * normal;
output->pointB -= rB * normal;
}
else
{
// Shapes are overlapped when radii are considered.
// Move the witness points to the middle.
b2Vec2 p = 0.5f * (output->pointA + output->pointB);
output->pointA = p;
output->pointB = p;
output->distance = 0.0f;
}
}
}
// GJK-raycast
// Algorithm by Gino van den Bergen.
// "Smooth Mesh Contacts with GJK" in Game Physics Pearls. 2010
bool b2ShapeCast(b2ShapeCastOutput * output, const b2ShapeCastInput * input)
{
output->iterations = 0;
output->lambda = 1.0f;
output->normal.SetZero();
output->point.SetZero();
const b2DistanceProxy* proxyA = &input->proxyA;
const b2DistanceProxy* proxyB = &input->proxyB;
float radiusA = b2Max(proxyA->m_radius, b2_polygonRadius);
float radiusB = b2Max(proxyB->m_radius, b2_polygonRadius);
float radius = radiusA + radiusB;
b2Transform xfA = input->transformA;
b2Transform xfB = input->transformB;
b2Vec2 r = input->translationB;
b2Vec2 n(0.0f, 0.0f);
float lambda = 0.0f;
// Initial simplex
b2Simplex simplex;
simplex.m_count = 0;
// Get simplex vertices as an array.
b2SimplexVertex* vertices = &simplex.m_v1;
// Get support point in -r direction
int32 indexA = proxyA->GetSupport(b2MulT(xfA.q, -r));
b2Vec2 wA = b2Mul(xfA, proxyA->GetVertex(indexA));
int32 indexB = proxyB->GetSupport(b2MulT(xfB.q, r));
b2Vec2 wB = b2Mul(xfB, proxyB->GetVertex(indexB));
b2Vec2 v = wA - wB;
// Sigma is the target distance between polygons
float sigma = b2Max(b2_polygonRadius, radius - b2_polygonRadius);
const float tolerance = 0.5f * b2_linearSlop;
// Main iteration loop.
const int32 k_maxIters = 20;
int32 iter = 0;
while (iter < k_maxIters && v.Length() - sigma > tolerance)
{
b2Assert(simplex.m_count < 3);
output->iterations += 1;
// Support in direction -v (A - B)
indexA = proxyA->GetSupport(b2MulT(xfA.q, -v));
wA = b2Mul(xfA, proxyA->GetVertex(indexA));
indexB = proxyB->GetSupport(b2MulT(xfB.q, v));
wB = b2Mul(xfB, proxyB->GetVertex(indexB));
b2Vec2 p = wA - wB;
// -v is a normal at p
v.Normalize();
// Intersect ray with plane
float vp = b2Dot(v, p);
float vr = b2Dot(v, r);
if (vp - sigma > lambda * vr)
{
if (vr <= 0.0f)
{
return false;
}
lambda = (vp - sigma) / vr;
if (lambda > 1.0f)
{
return false;
}
n = -v;
simplex.m_count = 0;
}
// Reverse simplex since it works with B - A.
// Shift by lambda * r because we want the closest point to the current clip point.
// Note that the support point p is not shifted because we want the plane equation
// to be formed in unshifted space.
b2SimplexVertex* vertex = vertices + simplex.m_count;
vertex->indexA = indexB;
vertex->wA = wB + lambda * r;
vertex->indexB = indexA;
vertex->wB = wA;
vertex->w = vertex->wB - vertex->wA;
vertex->a = 1.0f;
simplex.m_count += 1;
switch (simplex.m_count)
{
case 1:
break;
case 2:
simplex.Solve2();
break;
case 3:
simplex.Solve3();
break;
default:
b2Assert(false);
}
// If we have 3 points, then the origin is in the corresponding triangle.
if (simplex.m_count == 3)
{
// Overlap
return false;
}
// Get search direction.
v = simplex.GetClosestPoint();
// Iteration count is equated to the number of support point calls.
++iter;
}
if (iter == 0)
{
// Initial overlap
return false;
}
// Prepare output.
b2Vec2 pointA, pointB;
simplex.GetWitnessPoints(&pointB, &pointA);
if (v.LengthSquared() > 0.0f)
{
n = -v;
n.Normalize();
}
output->point = pointA + radiusA * n;
output->normal = n;
output->lambda = lambda;
output->iterations = iter;
return true;
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_dynamic_tree.h"
#include <string.h>
b2DynamicTree::b2DynamicTree()
{
m_root = b2_nullNode;
m_nodeCapacity = 16;
m_nodeCount = 0;
m_nodes = (b2TreeNode*)b2Alloc(m_nodeCapacity * sizeof(b2TreeNode));
memset(m_nodes, 0, m_nodeCapacity * sizeof(b2TreeNode));
// Build a linked list for the free list.
for (int32 i = 0; i < m_nodeCapacity - 1; ++i)
{
m_nodes[i].next = i + 1;
m_nodes[i].height = -1;
}
m_nodes[m_nodeCapacity-1].next = b2_nullNode;
m_nodes[m_nodeCapacity-1].height = -1;
m_freeList = 0;
m_insertionCount = 0;
}
b2DynamicTree::~b2DynamicTree()
{
// This frees the entire tree in one shot.
b2Free(m_nodes);
}
// Allocate a node from the pool. Grow the pool if necessary.
int32 b2DynamicTree::AllocateNode()
{
// Expand the node pool as needed.
if (m_freeList == b2_nullNode)
{
b2Assert(m_nodeCount == m_nodeCapacity);
// The free list is empty. Rebuild a bigger pool.
b2TreeNode* oldNodes = m_nodes;
m_nodeCapacity *= 2;
m_nodes = (b2TreeNode*)b2Alloc(m_nodeCapacity * sizeof(b2TreeNode));
memcpy(m_nodes, oldNodes, m_nodeCount * sizeof(b2TreeNode));
b2Free(oldNodes);
// Build a linked list for the free list. The parent
// pointer becomes the "next" pointer.
for (int32 i = m_nodeCount; i < m_nodeCapacity - 1; ++i)
{
m_nodes[i].next = i + 1;
m_nodes[i].height = -1;
}
m_nodes[m_nodeCapacity-1].next = b2_nullNode;
m_nodes[m_nodeCapacity-1].height = -1;
m_freeList = m_nodeCount;
}
// Peel a node off the free list.
int32 nodeId = m_freeList;
m_freeList = m_nodes[nodeId].next;
m_nodes[nodeId].parent = b2_nullNode;
m_nodes[nodeId].child1 = b2_nullNode;
m_nodes[nodeId].child2 = b2_nullNode;
m_nodes[nodeId].height = 0;
m_nodes[nodeId].userData = nullptr;
m_nodes[nodeId].moved = false;
++m_nodeCount;
return nodeId;
}
// Return a node to the pool.
void b2DynamicTree::FreeNode(int32 nodeId)
{
b2Assert(0 <= nodeId && nodeId < m_nodeCapacity);
b2Assert(0 < m_nodeCount);
m_nodes[nodeId].next = m_freeList;
m_nodes[nodeId].height = -1;
m_freeList = nodeId;
--m_nodeCount;
}
// Create a proxy in the tree as a leaf node. We return the index
// of the node instead of a pointer so that we can grow
// the node pool.
int32 b2DynamicTree::CreateProxy(const b2AABB& aabb, void* userData)
{
int32 proxyId = AllocateNode();
// Fatten the aabb.
b2Vec2 r(b2_aabbExtension, b2_aabbExtension);
m_nodes[proxyId].aabb.lowerBound = aabb.lowerBound - r;
m_nodes[proxyId].aabb.upperBound = aabb.upperBound + r;
m_nodes[proxyId].userData = userData;
m_nodes[proxyId].height = 0;
m_nodes[proxyId].moved = true;
InsertLeaf(proxyId);
return proxyId;
}
void b2DynamicTree::DestroyProxy(int32 proxyId)
{
b2Assert(0 <= proxyId && proxyId < m_nodeCapacity);
b2Assert(m_nodes[proxyId].IsLeaf());
RemoveLeaf(proxyId);
FreeNode(proxyId);
}
bool b2DynamicTree::MoveProxy(int32 proxyId, const b2AABB& aabb, const b2Vec2& displacement)
{
b2Assert(0 <= proxyId && proxyId < m_nodeCapacity);
b2Assert(m_nodes[proxyId].IsLeaf());
// Extend AABB
b2AABB fatAABB;
b2Vec2 r(b2_aabbExtension, b2_aabbExtension);
fatAABB.lowerBound = aabb.lowerBound - r;
fatAABB.upperBound = aabb.upperBound + r;
// Predict AABB movement
b2Vec2 d = b2_aabbMultiplier * displacement;
if (d.x < 0.0f)
{
fatAABB.lowerBound.x += d.x;
}
else
{
fatAABB.upperBound.x += d.x;
}
if (d.y < 0.0f)
{
fatAABB.lowerBound.y += d.y;
}
else
{
fatAABB.upperBound.y += d.y;
}
const b2AABB& treeAABB = m_nodes[proxyId].aabb;
if (treeAABB.Contains(aabb))
{
// The tree AABB still contains the object, but it might be too large.
// Perhaps the object was moving fast but has since gone to sleep.
// The huge AABB is larger than the new fat AABB.
b2AABB hugeAABB;
hugeAABB.lowerBound = fatAABB.lowerBound - 4.0f * r;
hugeAABB.upperBound = fatAABB.upperBound + 4.0f * r;
if (hugeAABB.Contains(treeAABB))
{
// The tree AABB contains the object AABB and the tree AABB is
// not too large. No tree update needed.
return false;
}
// Otherwise the tree AABB is huge and needs to be shrunk
}
RemoveLeaf(proxyId);
m_nodes[proxyId].aabb = fatAABB;
InsertLeaf(proxyId);
m_nodes[proxyId].moved = true;
return true;
}
void b2DynamicTree::InsertLeaf(int32 leaf)
{
++m_insertionCount;
if (m_root == b2_nullNode)
{
m_root = leaf;
m_nodes[m_root].parent = b2_nullNode;
return;
}
// Find the best sibling for this node
b2AABB leafAABB = m_nodes[leaf].aabb;
int32 index = m_root;
while (m_nodes[index].IsLeaf() == false)
{
int32 child1 = m_nodes[index].child1;
int32 child2 = m_nodes[index].child2;
float area = m_nodes[index].aabb.GetPerimeter();
b2AABB combinedAABB;
combinedAABB.Combine(m_nodes[index].aabb, leafAABB);
float combinedArea = combinedAABB.GetPerimeter();
// Cost of creating a new parent for this node and the new leaf
float cost = 2.0f * combinedArea;
// Minimum cost of pushing the leaf further down the tree
float inheritanceCost = 2.0f * (combinedArea - area);
// Cost of descending into child1
float cost1;
if (m_nodes[child1].IsLeaf())
{
b2AABB aabb;
aabb.Combine(leafAABB, m_nodes[child1].aabb);
cost1 = aabb.GetPerimeter() + inheritanceCost;
}
else
{
b2AABB aabb;
aabb.Combine(leafAABB, m_nodes[child1].aabb);
float oldArea = m_nodes[child1].aabb.GetPerimeter();
float newArea = aabb.GetPerimeter();
cost1 = (newArea - oldArea) + inheritanceCost;
}
// Cost of descending into child2
float cost2;
if (m_nodes[child2].IsLeaf())
{
b2AABB aabb;
aabb.Combine(leafAABB, m_nodes[child2].aabb);
cost2 = aabb.GetPerimeter() + inheritanceCost;
}
else
{
b2AABB aabb;
aabb.Combine(leafAABB, m_nodes[child2].aabb);
float oldArea = m_nodes[child2].aabb.GetPerimeter();
float newArea = aabb.GetPerimeter();
cost2 = newArea - oldArea + inheritanceCost;
}
// Descend according to the minimum cost.
if (cost < cost1 && cost < cost2)
{
break;
}
// Descend
if (cost1 < cost2)
{
index = child1;
}
else
{
index = child2;
}
}
int32 sibling = index;
// Create a new parent.
int32 oldParent = m_nodes[sibling].parent;
int32 newParent = AllocateNode();
m_nodes[newParent].parent = oldParent;
m_nodes[newParent].userData = nullptr;
m_nodes[newParent].aabb.Combine(leafAABB, m_nodes[sibling].aabb);
m_nodes[newParent].height = m_nodes[sibling].height + 1;
if (oldParent != b2_nullNode)
{
// The sibling was not the root.
if (m_nodes[oldParent].child1 == sibling)
{
m_nodes[oldParent].child1 = newParent;
}
else
{
m_nodes[oldParent].child2 = newParent;
}
m_nodes[newParent].child1 = sibling;
m_nodes[newParent].child2 = leaf;
m_nodes[sibling].parent = newParent;
m_nodes[leaf].parent = newParent;
}
else
{
// The sibling was the root.
m_nodes[newParent].child1 = sibling;
m_nodes[newParent].child2 = leaf;
m_nodes[sibling].parent = newParent;
m_nodes[leaf].parent = newParent;
m_root = newParent;
}
// Walk back up the tree fixing heights and AABBs
index = m_nodes[leaf].parent;
while (index != b2_nullNode)
{
index = Balance(index);
int32 child1 = m_nodes[index].child1;
int32 child2 = m_nodes[index].child2;
b2Assert(child1 != b2_nullNode);
b2Assert(child2 != b2_nullNode);
m_nodes[index].height = 1 + b2Max(m_nodes[child1].height, m_nodes[child2].height);
m_nodes[index].aabb.Combine(m_nodes[child1].aabb, m_nodes[child2].aabb);
index = m_nodes[index].parent;
}
//Validate();
}
void b2DynamicTree::RemoveLeaf(int32 leaf)
{
if (leaf == m_root)
{
m_root = b2_nullNode;
return;
}
int32 parent = m_nodes[leaf].parent;
int32 grandParent = m_nodes[parent].parent;
int32 sibling;
if (m_nodes[parent].child1 == leaf)
{
sibling = m_nodes[parent].child2;
}
else
{
sibling = m_nodes[parent].child1;
}
if (grandParent != b2_nullNode)
{
// Destroy parent and connect sibling to grandParent.
if (m_nodes[grandParent].child1 == parent)
{
m_nodes[grandParent].child1 = sibling;
}
else
{
m_nodes[grandParent].child2 = sibling;
}
m_nodes[sibling].parent = grandParent;
FreeNode(parent);
// Adjust ancestor bounds.
int32 index = grandParent;
while (index != b2_nullNode)
{
index = Balance(index);
int32 child1 = m_nodes[index].child1;
int32 child2 = m_nodes[index].child2;
m_nodes[index].aabb.Combine(m_nodes[child1].aabb, m_nodes[child2].aabb);
m_nodes[index].height = 1 + b2Max(m_nodes[child1].height, m_nodes[child2].height);
index = m_nodes[index].parent;
}
}
else
{
m_root = sibling;
m_nodes[sibling].parent = b2_nullNode;
FreeNode(parent);
}
//Validate();
}
// Perform a left or right rotation if node A is imbalanced.
// Returns the new root index.
int32 b2DynamicTree::Balance(int32 iA)
{
b2Assert(iA != b2_nullNode);
b2TreeNode* A = m_nodes + iA;
if (A->IsLeaf() || A->height < 2)
{
return iA;
}
int32 iB = A->child1;
int32 iC = A->child2;
b2Assert(0 <= iB && iB < m_nodeCapacity);
b2Assert(0 <= iC && iC < m_nodeCapacity);
b2TreeNode* B = m_nodes + iB;
b2TreeNode* C = m_nodes + iC;
int32 balance = C->height - B->height;
// Rotate C up
if (balance > 1)
{
int32 iF = C->child1;
int32 iG = C->child2;
b2TreeNode* F = m_nodes + iF;
b2TreeNode* G = m_nodes + iG;
b2Assert(0 <= iF && iF < m_nodeCapacity);
b2Assert(0 <= iG && iG < m_nodeCapacity);
// Swap A and C
C->child1 = iA;
C->parent = A->parent;
A->parent = iC;
// A's old parent should point to C
if (C->parent != b2_nullNode)
{
if (m_nodes[C->parent].child1 == iA)
{
m_nodes[C->parent].child1 = iC;
}
else
{
b2Assert(m_nodes[C->parent].child2 == iA);
m_nodes[C->parent].child2 = iC;
}
}
else
{
m_root = iC;
}
// Rotate
if (F->height > G->height)
{
C->child2 = iF;
A->child2 = iG;
G->parent = iA;
A->aabb.Combine(B->aabb, G->aabb);
C->aabb.Combine(A->aabb, F->aabb);
A->height = 1 + b2Max(B->height, G->height);
C->height = 1 + b2Max(A->height, F->height);
}
else
{
C->child2 = iG;
A->child2 = iF;
F->parent = iA;
A->aabb.Combine(B->aabb, F->aabb);
C->aabb.Combine(A->aabb, G->aabb);
A->height = 1 + b2Max(B->height, F->height);
C->height = 1 + b2Max(A->height, G->height);
}
return iC;
}
// Rotate B up
if (balance < -1)
{
int32 iD = B->child1;
int32 iE = B->child2;
b2TreeNode* D = m_nodes + iD;
b2TreeNode* E = m_nodes + iE;
b2Assert(0 <= iD && iD < m_nodeCapacity);
b2Assert(0 <= iE && iE < m_nodeCapacity);
// Swap A and B
B->child1 = iA;
B->parent = A->parent;
A->parent = iB;
// A's old parent should point to B
if (B->parent != b2_nullNode)
{
if (m_nodes[B->parent].child1 == iA)
{
m_nodes[B->parent].child1 = iB;
}
else
{
b2Assert(m_nodes[B->parent].child2 == iA);
m_nodes[B->parent].child2 = iB;
}
}
else
{
m_root = iB;
}
// Rotate
if (D->height > E->height)
{
B->child2 = iD;
A->child1 = iE;
E->parent = iA;
A->aabb.Combine(C->aabb, E->aabb);
B->aabb.Combine(A->aabb, D->aabb);
A->height = 1 + b2Max(C->height, E->height);
B->height = 1 + b2Max(A->height, D->height);
}
else
{
B->child2 = iE;
A->child1 = iD;
D->parent = iA;
A->aabb.Combine(C->aabb, D->aabb);
B->aabb.Combine(A->aabb, E->aabb);
A->height = 1 + b2Max(C->height, D->height);
B->height = 1 + b2Max(A->height, E->height);
}
return iB;
}
return iA;
}
int32 b2DynamicTree::GetHeight() const
{
if (m_root == b2_nullNode)
{
return 0;
}
return m_nodes[m_root].height;
}
//
float b2DynamicTree::GetAreaRatio() const
{
if (m_root == b2_nullNode)
{
return 0.0f;
}
const b2TreeNode* root = m_nodes + m_root;
float rootArea = root->aabb.GetPerimeter();
float totalArea = 0.0f;
for (int32 i = 0; i < m_nodeCapacity; ++i)
{
const b2TreeNode* node = m_nodes + i;
if (node->height < 0)
{
// Free node in pool
continue;
}
totalArea += node->aabb.GetPerimeter();
}
return totalArea / rootArea;
}
// Compute the height of a sub-tree.
int32 b2DynamicTree::ComputeHeight(int32 nodeId) const
{
b2Assert(0 <= nodeId && nodeId < m_nodeCapacity);
b2TreeNode* node = m_nodes + nodeId;
if (node->IsLeaf())
{
return 0;
}
int32 height1 = ComputeHeight(node->child1);
int32 height2 = ComputeHeight(node->child2);
return 1 + b2Max(height1, height2);
}
int32 b2DynamicTree::ComputeHeight() const
{
int32 height = ComputeHeight(m_root);
return height;
}
void b2DynamicTree::ValidateStructure(int32 index) const
{
if (index == b2_nullNode)
{
return;
}
if (index == m_root)
{
b2Assert(m_nodes[index].parent == b2_nullNode);
}
const b2TreeNode* node = m_nodes + index;
int32 child1 = node->child1;
int32 child2 = node->child2;
if (node->IsLeaf())
{
b2Assert(child1 == b2_nullNode);
b2Assert(child2 == b2_nullNode);
b2Assert(node->height == 0);
return;
}
b2Assert(0 <= child1 && child1 < m_nodeCapacity);
b2Assert(0 <= child2 && child2 < m_nodeCapacity);
b2Assert(m_nodes[child1].parent == index);
b2Assert(m_nodes[child2].parent == index);
ValidateStructure(child1);
ValidateStructure(child2);
}
void b2DynamicTree::ValidateMetrics(int32 index) const
{
if (index == b2_nullNode)
{
return;
}
const b2TreeNode* node = m_nodes + index;
int32 child1 = node->child1;
int32 child2 = node->child2;
if (node->IsLeaf())
{
b2Assert(child1 == b2_nullNode);
b2Assert(child2 == b2_nullNode);
b2Assert(node->height == 0);
return;
}
b2Assert(0 <= child1 && child1 < m_nodeCapacity);
b2Assert(0 <= child2 && child2 < m_nodeCapacity);
int32 height1 = m_nodes[child1].height;
int32 height2 = m_nodes[child2].height;
int32 height;
height = 1 + b2Max(height1, height2);
b2Assert(node->height == height);
b2AABB aabb;
aabb.Combine(m_nodes[child1].aabb, m_nodes[child2].aabb);
b2Assert(aabb.lowerBound == node->aabb.lowerBound);
b2Assert(aabb.upperBound == node->aabb.upperBound);
ValidateMetrics(child1);
ValidateMetrics(child2);
}
void b2DynamicTree::Validate() const
{
#if defined(b2DEBUG)
ValidateStructure(m_root);
ValidateMetrics(m_root);
int32 freeCount = 0;
int32 freeIndex = m_freeList;
while (freeIndex != b2_nullNode)
{
b2Assert(0 <= freeIndex && freeIndex < m_nodeCapacity);
freeIndex = m_nodes[freeIndex].next;
++freeCount;
}
b2Assert(GetHeight() == ComputeHeight());
b2Assert(m_nodeCount + freeCount == m_nodeCapacity);
#endif
}
int32 b2DynamicTree::GetMaxBalance() const
{
int32 maxBalance = 0;
for (int32 i = 0; i < m_nodeCapacity; ++i)
{
const b2TreeNode* node = m_nodes + i;
if (node->height <= 1)
{
continue;
}
b2Assert(node->IsLeaf() == false);
int32 child1 = node->child1;
int32 child2 = node->child2;
int32 balance = b2Abs(m_nodes[child2].height - m_nodes[child1].height);
maxBalance = b2Max(maxBalance, balance);
}
return maxBalance;
}
void b2DynamicTree::RebuildBottomUp()
{
int32* nodes = (int32*)b2Alloc(m_nodeCount * sizeof(int32));
int32 count = 0;
// Build array of leaves. Free the rest.
for (int32 i = 0; i < m_nodeCapacity; ++i)
{
if (m_nodes[i].height < 0)
{
// free node in pool
continue;
}
if (m_nodes[i].IsLeaf())
{
m_nodes[i].parent = b2_nullNode;
nodes[count] = i;
++count;
}
else
{
FreeNode(i);
}
}
while (count > 1)
{
float minCost = b2_maxFloat;
int32 iMin = -1, jMin = -1;
for (int32 i = 0; i < count; ++i)
{
b2AABB aabbi = m_nodes[nodes[i]].aabb;
for (int32 j = i + 1; j < count; ++j)
{
b2AABB aabbj = m_nodes[nodes[j]].aabb;
b2AABB b;
b.Combine(aabbi, aabbj);
float cost = b.GetPerimeter();
if (cost < minCost)
{
iMin = i;
jMin = j;
minCost = cost;
}
}
}
int32 index1 = nodes[iMin];
int32 index2 = nodes[jMin];
b2TreeNode* child1 = m_nodes + index1;
b2TreeNode* child2 = m_nodes + index2;
int32 parentIndex = AllocateNode();
b2TreeNode* parent = m_nodes + parentIndex;
parent->child1 = index1;
parent->child2 = index2;
parent->height = 1 + b2Max(child1->height, child2->height);
parent->aabb.Combine(child1->aabb, child2->aabb);
parent->parent = b2_nullNode;
child1->parent = parentIndex;
child2->parent = parentIndex;
nodes[jMin] = nodes[count-1];
nodes[iMin] = parentIndex;
--count;
}
m_root = nodes[0];
b2Free(nodes);
Validate();
}
void b2DynamicTree::ShiftOrigin(const b2Vec2& newOrigin)
{
// Build array of leaves. Free the rest.
for (int32 i = 0; i < m_nodeCapacity; ++i)
{
m_nodes[i].aabb.lowerBound -= newOrigin;
m_nodes[i].aabb.upperBound -= newOrigin;
}
}

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3-mid/physics/implement/box2d/contrib/src/collision/b2_edge_shape.cpp Normal file
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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_edge_shape.h"
#include "box2d/b2_block_allocator.h"
#include <new>
void b2EdgeShape::SetOneSided(const b2Vec2& v0, const b2Vec2& v1, const b2Vec2& v2, const b2Vec2& v3)
{
m_vertex0 = v0;
m_vertex1 = v1;
m_vertex2 = v2;
m_vertex3 = v3;
m_oneSided = true;
}
void b2EdgeShape::SetTwoSided(const b2Vec2& v1, const b2Vec2& v2)
{
m_vertex1 = v1;
m_vertex2 = v2;
m_oneSided = false;
}
b2Shape* b2EdgeShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2EdgeShape));
b2EdgeShape* clone = new (mem) b2EdgeShape;
*clone = *this;
return clone;
}
int32 b2EdgeShape::GetChildCount() const
{
return 1;
}
bool b2EdgeShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
{
B2_NOT_USED(xf);
B2_NOT_USED(p);
return false;
}
// p = p1 + t * d
// v = v1 + s * e
// p1 + t * d = v1 + s * e
// s * e - t * d = p1 - v1
bool b2EdgeShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& xf, int32 childIndex) const
{
B2_NOT_USED(childIndex);
// Put the ray into the edge's frame of reference.
b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
b2Vec2 d = p2 - p1;
b2Vec2 v1 = m_vertex1;
b2Vec2 v2 = m_vertex2;
b2Vec2 e = v2 - v1;
// Normal points to the right, looking from v1 at v2
b2Vec2 normal(e.y, -e.x);
normal.Normalize();
// q = p1 + t * d
// dot(normal, q - v1) = 0
// dot(normal, p1 - v1) + t * dot(normal, d) = 0
float numerator = b2Dot(normal, v1 - p1);
if (m_oneSided && numerator > 0.0f)
{
return false;
}
float denominator = b2Dot(normal, d);
if (denominator == 0.0f)
{
return false;
}
float t = numerator / denominator;
if (t < 0.0f || input.maxFraction < t)
{
return false;
}
b2Vec2 q = p1 + t * d;
// q = v1 + s * r
// s = dot(q - v1, r) / dot(r, r)
b2Vec2 r = v2 - v1;
float rr = b2Dot(r, r);
if (rr == 0.0f)
{
return false;
}
float s = b2Dot(q - v1, r) / rr;
if (s < 0.0f || 1.0f < s)
{
return false;
}
output->fraction = t;
if (numerator > 0.0f)
{
output->normal = -b2Mul(xf.q, normal);
}
else
{
output->normal = b2Mul(xf.q, normal);
}
return true;
}
void b2EdgeShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
{
B2_NOT_USED(childIndex);
b2Vec2 v1 = b2Mul(xf, m_vertex1);
b2Vec2 v2 = b2Mul(xf, m_vertex2);
b2Vec2 lower = b2Min(v1, v2);
b2Vec2 upper = b2Max(v1, v2);
b2Vec2 r(m_radius, m_radius);
aabb->lowerBound = lower - r;
aabb->upperBound = upper + r;
}
void b2EdgeShape::ComputeMass(b2MassData* massData, float density) const
{
B2_NOT_USED(density);
massData->mass = 0.0f;
massData->center = 0.5f * (m_vertex1 + m_vertex2);
massData->I = 0.0f;
}

459
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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_polygon_shape.h"
#include "box2d/b2_block_allocator.h"
#include <new>
b2Shape* b2PolygonShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2PolygonShape));
b2PolygonShape* clone = new (mem) b2PolygonShape;
*clone = *this;
return clone;
}
void b2PolygonShape::SetAsBox(float hx, float hy)
{
m_count = 4;
m_vertices[0].Set(-hx, -hy);
m_vertices[1].Set( hx, -hy);
m_vertices[2].Set( hx, hy);
m_vertices[3].Set(-hx, hy);
m_normals[0].Set(0.0f, -1.0f);
m_normals[1].Set(1.0f, 0.0f);
m_normals[2].Set(0.0f, 1.0f);
m_normals[3].Set(-1.0f, 0.0f);
m_centroid.SetZero();
}
void b2PolygonShape::SetAsBox(float hx, float hy, const b2Vec2& center, float angle)
{
m_count = 4;
m_vertices[0].Set(-hx, -hy);
m_vertices[1].Set( hx, -hy);
m_vertices[2].Set( hx, hy);
m_vertices[3].Set(-hx, hy);
m_normals[0].Set(0.0f, -1.0f);
m_normals[1].Set(1.0f, 0.0f);
m_normals[2].Set(0.0f, 1.0f);
m_normals[3].Set(-1.0f, 0.0f);
m_centroid = center;
b2Transform xf;
xf.p = center;
xf.q.Set(angle);
// Transform vertices and normals.
for (int32 i = 0; i < m_count; ++i)
{
m_vertices[i] = b2Mul(xf, m_vertices[i]);
m_normals[i] = b2Mul(xf.q, m_normals[i]);
}
}
int32 b2PolygonShape::GetChildCount() const
{
return 1;
}
static b2Vec2 ComputeCentroid(const b2Vec2* vs, int32 count)
{
b2Assert(count >= 3);
b2Vec2 c(0.0f, 0.0f);
float area = 0.0f;
// Get a reference point for forming triangles.
// Use the first vertex to reduce round-off errors.
b2Vec2 s = vs[0];
const float inv3 = 1.0f / 3.0f;
for (int32 i = 0; i < count; ++i)
{
// Triangle vertices.
b2Vec2 p1 = vs[0] - s;
b2Vec2 p2 = vs[i] - s;
b2Vec2 p3 = i + 1 < count ? vs[i+1] - s : vs[0] - s;
b2Vec2 e1 = p2 - p1;
b2Vec2 e2 = p3 - p1;
float D = b2Cross(e1, e2);
float triangleArea = 0.5f * D;
area += triangleArea;
// Area weighted centroid
c += triangleArea * inv3 * (p1 + p2 + p3);
}
// Centroid
b2Assert(area > b2_epsilon);
c = (1.0f / area) * c + s;
return c;
}
void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
{
b2Assert(3 <= count && count <= b2_maxPolygonVertices);
if (count < 3)
{
SetAsBox(1.0f, 1.0f);
return;
}
int32 n = b2Min(count, b2_maxPolygonVertices);
// Perform welding and copy vertices into local buffer.
b2Vec2 ps[b2_maxPolygonVertices];
int32 tempCount = 0;
for (int32 i = 0; i < n; ++i)
{
b2Vec2 v = vertices[i];
bool unique = true;
for (int32 j = 0; j < tempCount; ++j)
{
if (b2DistanceSquared(v, ps[j]) < ((0.5f * b2_linearSlop) * (0.5f * b2_linearSlop)))
{
unique = false;
break;
}
}
if (unique)
{
ps[tempCount++] = v;
}
}
n = tempCount;
if (n < 3)
{
// Polygon is degenerate.
b2Assert(false);
SetAsBox(1.0f, 1.0f);
return;
}
// Create the convex hull using the Gift wrapping algorithm
// http://en.wikipedia.org/wiki/Gift_wrapping_algorithm
// Find the right most point on the hull
int32 i0 = 0;
float x0 = ps[0].x;
for (int32 i = 1; i < n; ++i)
{
float x = ps[i].x;
if (x > x0 || (x == x0 && ps[i].y < ps[i0].y))
{
i0 = i;
x0 = x;
}
}
int32 hull[b2_maxPolygonVertices];
int32 m = 0;
int32 ih = i0;
for (;;)
{
b2Assert(m < b2_maxPolygonVertices);
hull[m] = ih;
int32 ie = 0;
for (int32 j = 1; j < n; ++j)
{
if (ie == ih)
{
ie = j;
continue;
}
b2Vec2 r = ps[ie] - ps[hull[m]];
b2Vec2 v = ps[j] - ps[hull[m]];
float c = b2Cross(r, v);
if (c < 0.0f)
{
ie = j;
}
// Collinearity check
if (c == 0.0f && v.LengthSquared() > r.LengthSquared())
{
ie = j;
}
}
++m;
ih = ie;
if (ie == i0)
{
break;
}
}
if (m < 3)
{
// Polygon is degenerate.
b2Assert(false);
SetAsBox(1.0f, 1.0f);
return;
}
m_count = m;
// Copy vertices.
for (int32 i = 0; i < m; ++i)
{
m_vertices[i] = ps[hull[i]];
}
// Compute normals. Ensure the edges have non-zero length.
for (int32 i = 0; i < m; ++i)
{
int32 i1 = i;
int32 i2 = i + 1 < m ? i + 1 : 0;
b2Vec2 edge = m_vertices[i2] - m_vertices[i1];
b2Assert(edge.LengthSquared() > b2_epsilon * b2_epsilon);
m_normals[i] = b2Cross(edge, 1.0f);
m_normals[i].Normalize();
}
// Compute the polygon centroid.
m_centroid = ComputeCentroid(m_vertices, m);
}
bool b2PolygonShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
{
b2Vec2 pLocal = b2MulT(xf.q, p - xf.p);
for (int32 i = 0; i < m_count; ++i)
{
float dot = b2Dot(m_normals[i], pLocal - m_vertices[i]);
if (dot > 0.0f)
{
return false;
}
}
return true;
}
bool b2PolygonShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& xf, int32 childIndex) const
{
B2_NOT_USED(childIndex);
// Put the ray into the polygon's frame of reference.
b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
b2Vec2 d = p2 - p1;
float lower = 0.0f, upper = input.maxFraction;
int32 index = -1;
for (int32 i = 0; i < m_count; ++i)
{
// p = p1 + a * d
// dot(normal, p - v) = 0
// dot(normal, p1 - v) + a * dot(normal, d) = 0
float numerator = b2Dot(m_normals[i], m_vertices[i] - p1);
float denominator = b2Dot(m_normals[i], d);
if (denominator == 0.0f)
{
if (numerator < 0.0f)
{
return false;
}
}
else
{
// Note: we want this predicate without division:
// lower < numerator / denominator, where denominator < 0
// Since denominator < 0, we have to flip the inequality:
// lower < numerator / denominator <==> denominator * lower > numerator.
if (denominator < 0.0f && numerator < lower * denominator)
{
// Increase lower.
// The segment enters this half-space.
lower = numerator / denominator;
index = i;
}
else if (denominator > 0.0f && numerator < upper * denominator)
{
// Decrease upper.
// The segment exits this half-space.
upper = numerator / denominator;
}
}
// The use of epsilon here causes the assert on lower to trip
// in some cases. Apparently the use of epsilon was to make edge
// shapes work, but now those are handled separately.
//if (upper < lower - b2_epsilon)
if (upper < lower)
{
return false;
}
}
b2Assert(0.0f <= lower && lower <= input.maxFraction);
if (index >= 0)
{
output->fraction = lower;
output->normal = b2Mul(xf.q, m_normals[index]);
return true;
}
return false;
}
void b2PolygonShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
{
B2_NOT_USED(childIndex);
b2Vec2 lower = b2Mul(xf, m_vertices[0]);
b2Vec2 upper = lower;
for (int32 i = 1; i < m_count; ++i)
{
b2Vec2 v = b2Mul(xf, m_vertices[i]);
lower = b2Min(lower, v);
upper = b2Max(upper, v);
}
b2Vec2 r(m_radius, m_radius);
aabb->lowerBound = lower - r;
aabb->upperBound = upper + r;
}
void b2PolygonShape::ComputeMass(b2MassData* massData, float density) const
{
// Polygon mass, centroid, and inertia.
// Let rho be the polygon density in mass per unit area.
// Then:
// mass = rho * int(dA)
// centroid.x = (1/mass) * rho * int(x * dA)
// centroid.y = (1/mass) * rho * int(y * dA)
// I = rho * int((x*x + y*y) * dA)
//
// We can compute these integrals by summing all the integrals
// for each triangle of the polygon. To evaluate the integral
// for a single triangle, we make a change of variables to
// the (u,v) coordinates of the triangle:
// x = x0 + e1x * u + e2x * v
// y = y0 + e1y * u + e2y * v
// where 0 <= u && 0 <= v && u + v <= 1.
//
// We integrate u from [0,1-v] and then v from [0,1].
// We also need to use the Jacobian of the transformation:
// D = cross(e1, e2)
//
// Simplification: triangle centroid = (1/3) * (p1 + p2 + p3)
//
// The rest of the derivation is handled by computer algebra.
b2Assert(m_count >= 3);
b2Vec2 center(0.0f, 0.0f);
float area = 0.0f;
float I = 0.0f;
// Get a reference point for forming triangles.
// Use the first vertex to reduce round-off errors.
b2Vec2 s = m_vertices[0];
const float k_inv3 = 1.0f / 3.0f;
for (int32 i = 0; i < m_count; ++i)
{
// Triangle vertices.
b2Vec2 e1 = m_vertices[i] - s;
b2Vec2 e2 = i + 1 < m_count ? m_vertices[i+1] - s : m_vertices[0] - s;
float D = b2Cross(e1, e2);
float triangleArea = 0.5f * D;
area += triangleArea;
// Area weighted centroid
center += triangleArea * k_inv3 * (e1 + e2);
float ex1 = e1.x, ey1 = e1.y;
float ex2 = e2.x, ey2 = e2.y;
float intx2 = ex1*ex1 + ex2*ex1 + ex2*ex2;
float inty2 = ey1*ey1 + ey2*ey1 + ey2*ey2;
I += (0.25f * k_inv3 * D) * (intx2 + inty2);
}
// Total mass
massData->mass = density * area;
// Center of mass
b2Assert(area > b2_epsilon);
center *= 1.0f / area;
massData->center = center + s;
// Inertia tensor relative to the local origin (point s).
massData->I = density * I;
// Shift to center of mass then to original body origin.
massData->I += massData->mass * (b2Dot(massData->center, massData->center) - b2Dot(center, center));
}
bool b2PolygonShape::Validate() const
{
for (int32 i = 0; i < m_count; ++i)
{
int32 i1 = i;
int32 i2 = i < m_count - 1 ? i1 + 1 : 0;
b2Vec2 p = m_vertices[i1];
b2Vec2 e = m_vertices[i2] - p;
for (int32 j = 0; j < m_count; ++j)
{
if (j == i1 || j == i2)
{
continue;
}
b2Vec2 v = m_vertices[j] - p;
float c = b2Cross(e, v);
if (c < 0.0f)
{
return false;
}
}
}
return true;
}

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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/b2_collision.h"
#include "box2d/b2_distance.h"
#include "box2d/b2_circle_shape.h"
#include "box2d/b2_polygon_shape.h"
#include "box2d/b2_time_of_impact.h"
#include "box2d/b2_timer.h"
#include <stdio.h>
B2_API float b2_toiTime, b2_toiMaxTime;
B2_API int32 b2_toiCalls, b2_toiIters, b2_toiMaxIters;
B2_API int32 b2_toiRootIters, b2_toiMaxRootIters;
//
struct b2SeparationFunction
{
enum Type
{
e_points,
e_faceA,
e_faceB
};
// TODO_ERIN might not need to return the separation
float Initialize(const b2SimplexCache* cache,
const b2DistanceProxy* proxyA, const b2Sweep& sweepA,
const b2DistanceProxy* proxyB, const b2Sweep& sweepB,
float t1)
{
m_proxyA = proxyA;
m_proxyB = proxyB;
int32 count = cache->count;
b2Assert(0 < count && count < 3);
m_sweepA = sweepA;
m_sweepB = sweepB;
b2Transform xfA, xfB;
m_sweepA.GetTransform(&xfA, t1);
m_sweepB.GetTransform(&xfB, t1);
if (count == 1)
{
m_type = e_points;
b2Vec2 localPointA = m_proxyA->GetVertex(cache->indexA[0]);
b2Vec2 localPointB = m_proxyB->GetVertex(cache->indexB[0]);
b2Vec2 pointA = b2Mul(xfA, localPointA);
b2Vec2 pointB = b2Mul(xfB, localPointB);
m_axis = pointB - pointA;
float s = m_axis.Normalize();
return s;
}
else if (cache->indexA[0] == cache->indexA[1])
{
// Two points on B and one on A.
m_type = e_faceB;
b2Vec2 localPointB1 = proxyB->GetVertex(cache->indexB[0]);
b2Vec2 localPointB2 = proxyB->GetVertex(cache->indexB[1]);
m_axis = b2Cross(localPointB2 - localPointB1, 1.0f);
m_axis.Normalize();
b2Vec2 normal = b2Mul(xfB.q, m_axis);
m_localPoint = 0.5f * (localPointB1 + localPointB2);
b2Vec2 pointB = b2Mul(xfB, m_localPoint);
b2Vec2 localPointA = proxyA->GetVertex(cache->indexA[0]);
b2Vec2 pointA = b2Mul(xfA, localPointA);
float s = b2Dot(pointA - pointB, normal);
if (s < 0.0f)
{
m_axis = -m_axis;
s = -s;
}
return s;
}
else
{
// Two points on A and one or two points on B.
m_type = e_faceA;
b2Vec2 localPointA1 = m_proxyA->GetVertex(cache->indexA[0]);
b2Vec2 localPointA2 = m_proxyA->GetVertex(cache->indexA[1]);
m_axis = b2Cross(localPointA2 - localPointA1, 1.0f);
m_axis.Normalize();
b2Vec2 normal = b2Mul(xfA.q, m_axis);
m_localPoint = 0.5f * (localPointA1 + localPointA2);
b2Vec2 pointA = b2Mul(xfA, m_localPoint);
b2Vec2 localPointB = m_proxyB->GetVertex(cache->indexB[0]);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float s = b2Dot(pointB - pointA, normal);
if (s < 0.0f)
{
m_axis = -m_axis;
s = -s;
}
return s;
}
}
//
float FindMinSeparation(int32* indexA, int32* indexB, float t) const
{
b2Transform xfA, xfB;
m_sweepA.GetTransform(&xfA, t);
m_sweepB.GetTransform(&xfB, t);
switch (m_type)
{
case e_points:
{
b2Vec2 axisA = b2MulT(xfA.q, m_axis);
b2Vec2 axisB = b2MulT(xfB.q, -m_axis);
*indexA = m_proxyA->GetSupport(axisA);
*indexB = m_proxyB->GetSupport(axisB);
b2Vec2 localPointA = m_proxyA->GetVertex(*indexA);
b2Vec2 localPointB = m_proxyB->GetVertex(*indexB);
b2Vec2 pointA = b2Mul(xfA, localPointA);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float separation = b2Dot(pointB - pointA, m_axis);
return separation;
}
case e_faceA:
{
b2Vec2 normal = b2Mul(xfA.q, m_axis);
b2Vec2 pointA = b2Mul(xfA, m_localPoint);
b2Vec2 axisB = b2MulT(xfB.q, -normal);
*indexA = -1;
*indexB = m_proxyB->GetSupport(axisB);
b2Vec2 localPointB = m_proxyB->GetVertex(*indexB);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float separation = b2Dot(pointB - pointA, normal);
return separation;
}
case e_faceB:
{
b2Vec2 normal = b2Mul(xfB.q, m_axis);
b2Vec2 pointB = b2Mul(xfB, m_localPoint);
b2Vec2 axisA = b2MulT(xfA.q, -normal);
*indexB = -1;
*indexA = m_proxyA->GetSupport(axisA);
b2Vec2 localPointA = m_proxyA->GetVertex(*indexA);
b2Vec2 pointA = b2Mul(xfA, localPointA);
float separation = b2Dot(pointA - pointB, normal);
return separation;
}
default:
b2Assert(false);
*indexA = -1;
*indexB = -1;
return 0.0f;
}
}
//
float Evaluate(int32 indexA, int32 indexB, float t) const
{
b2Transform xfA, xfB;
m_sweepA.GetTransform(&xfA, t);
m_sweepB.GetTransform(&xfB, t);
switch (m_type)
{
case e_points:
{
b2Vec2 localPointA = m_proxyA->GetVertex(indexA);
b2Vec2 localPointB = m_proxyB->GetVertex(indexB);
b2Vec2 pointA = b2Mul(xfA, localPointA);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float separation = b2Dot(pointB - pointA, m_axis);
return separation;
}
case e_faceA:
{
b2Vec2 normal = b2Mul(xfA.q, m_axis);
b2Vec2 pointA = b2Mul(xfA, m_localPoint);
b2Vec2 localPointB = m_proxyB->GetVertex(indexB);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float separation = b2Dot(pointB - pointA, normal);
return separation;
}
case e_faceB:
{
b2Vec2 normal = b2Mul(xfB.q, m_axis);
b2Vec2 pointB = b2Mul(xfB, m_localPoint);
b2Vec2 localPointA = m_proxyA->GetVertex(indexA);
b2Vec2 pointA = b2Mul(xfA, localPointA);
float separation = b2Dot(pointA - pointB, normal);
return separation;
}
default:
b2Assert(false);
return 0.0f;
}
}
const b2DistanceProxy* m_proxyA;
const b2DistanceProxy* m_proxyB;
b2Sweep m_sweepA, m_sweepB;
Type m_type;
b2Vec2 m_localPoint;
b2Vec2 m_axis;
};
// CCD via the local separating axis method. This seeks progression
// by computing the largest time at which separation is maintained.
void b2TimeOfImpact(b2TOIOutput* output, const b2TOIInput* input)
{
b2Timer timer;
++b2_toiCalls;
output->state = b2TOIOutput::e_unknown;
output->t = input->tMax;
const b2DistanceProxy* proxyA = &input->proxyA;
const b2DistanceProxy* proxyB = &input->proxyB;
b2Sweep sweepA = input->sweepA;
b2Sweep sweepB = input->sweepB;
// Large rotations can make the root finder fail, so we normalize the
// sweep angles.
sweepA.Normalize();
sweepB.Normalize();
float tMax = input->tMax;
float totalRadius = proxyA->m_radius + proxyB->m_radius;
float target = b2Max(b2_linearSlop, totalRadius - 3.0f * b2_linearSlop);
float tolerance = 0.25f * b2_linearSlop;
b2Assert(target > tolerance);
float t1 = 0.0f;
const int32 k_maxIterations = 20; // TODO_ERIN b2Settings
int32 iter = 0;
// Prepare input for distance query.
b2SimplexCache cache;
cache.count = 0;
b2DistanceInput distanceInput;
distanceInput.proxyA = input->proxyA;
distanceInput.proxyB = input->proxyB;
distanceInput.useRadii = false;
// The outer loop progressively attempts to compute new separating axes.
// This loop terminates when an axis is repeated (no progress is made).
for(;;)
{
b2Transform xfA, xfB;
sweepA.GetTransform(&xfA, t1);
sweepB.GetTransform(&xfB, t1);
// Get the distance between shapes. We can also use the results
// to get a separating axis.
distanceInput.transformA = xfA;
distanceInput.transformB = xfB;
b2DistanceOutput distanceOutput;
b2Distance(&distanceOutput, &cache, &distanceInput);
// If the shapes are overlapped, we give up on continuous collision.
if (distanceOutput.distance <= 0.0f)
{
// Failure!
output->state = b2TOIOutput::e_overlapped;
output->t = 0.0f;
break;
}
if (distanceOutput.distance < target + tolerance)
{
// Victory!
output->state = b2TOIOutput::e_touching;
output->t = t1;
break;
}
// Initialize the separating axis.
b2SeparationFunction fcn;
fcn.Initialize(&cache, proxyA, sweepA, proxyB, sweepB, t1);
#if 0
// Dump the curve seen by the root finder
{
const int32 N = 100;
float dx = 1.0f / N;
float xs[N+1];
float fs[N+1];
float x = 0.0f;
for (int32 i = 0; i <= N; ++i)
{
sweepA.GetTransform(&xfA, x);
sweepB.GetTransform(&xfB, x);
float f = fcn.Evaluate(xfA, xfB) - target;
printf("%g %g\n", x, f);
xs[i] = x;
fs[i] = f;
x += dx;
}
}
#endif
// Compute the TOI on the separating axis. We do this by successively
// resolving the deepest point. This loop is bounded by the number of vertices.
bool done = false;
float t2 = tMax;
int32 pushBackIter = 0;
for (;;)
{
// Find the deepest point at t2. Store the witness point indices.
int32 indexA, indexB;
float s2 = fcn.FindMinSeparation(&indexA, &indexB, t2);
// Is the final configuration separated?
if (s2 > target + tolerance)
{
// Victory!
output->state = b2TOIOutput::e_separated;
output->t = tMax;
done = true;
break;
}
// Has the separation reached tolerance?
if (s2 > target - tolerance)
{
// Advance the sweeps
t1 = t2;
break;
}
// Compute the initial separation of the witness points.
float s1 = fcn.Evaluate(indexA, indexB, t1);
// Check for initial overlap. This might happen if the root finder
// runs out of iterations.
if (s1 < target - tolerance)
{
output->state = b2TOIOutput::e_failed;
output->t = t1;
done = true;
break;
}
// Check for touching
if (s1 <= target + tolerance)
{
// Victory! t1 should hold the TOI (could be 0.0).
output->state = b2TOIOutput::e_touching;
output->t = t1;
done = true;
break;
}
// Compute 1D root of: f(x) - target = 0
int32 rootIterCount = 0;
float a1 = t1, a2 = t2;
for (;;)
{
// Use a mix of the secant rule and bisection.
float t;
if (rootIterCount & 1)
{
// Secant rule to improve convergence.
t = a1 + (target - s1) * (a2 - a1) / (s2 - s1);
}
else
{
// Bisection to guarantee progress.
t = 0.5f * (a1 + a2);
}
++rootIterCount;
++b2_toiRootIters;
float s = fcn.Evaluate(indexA, indexB, t);
if (b2Abs(s - target) < tolerance)
{
// t2 holds a tentative value for t1
t2 = t;
break;
}
// Ensure we continue to bracket the root.
if (s > target)
{
a1 = t;
s1 = s;
}
else
{
a2 = t;
s2 = s;
}
if (rootIterCount == 50)
{
break;
}
}
b2_toiMaxRootIters = b2Max(b2_toiMaxRootIters, rootIterCount);
++pushBackIter;
if (pushBackIter == b2_maxPolygonVertices)
{
break;
}
}
++iter;
++b2_toiIters;
if (done)
{
break;
}
if (iter == k_maxIterations)
{
// Root finder got stuck. Semi-victory.
output->state = b2TOIOutput::e_failed;
output->t = t1;
break;
}
}
b2_toiMaxIters = b2Max(b2_toiMaxIters, iter);
float time = timer.GetMilliseconds();
b2_toiMaxTime = b2Max(b2_toiMaxTime, time);
b2_toiTime += time;
}