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Projection friction impulses on an implicit cone instead of a pyramidal approximation.

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This commit is contained in:
Crozet Sébastien
2021-03-07 11:43:47 +01:00
parent e7f805aea4
commit bed47a82e7
15 changed files with 618 additions and 218 deletions
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154
src/dynamics/solver/velocity_ground_constraint.rs
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@@ -1,13 +1,42 @@
use super::{AnyVelocityConstraint, DeltaVel};
use crate::math::{AngVector, Real, Vector, DIM, MAX_MANIFOLD_POINTS};
use crate::utils::{WAngularInertia, WBasis, WCross, WDot};
#[cfg(feature = "dim2")]
use crate::utils::WBasis;
use crate::utils::{WAngularInertia, WCross, WDot};
use crate::dynamics::{IntegrationParameters, RigidBodySet};
use crate::geometry::{ContactManifold, ContactManifoldIndex};
use simba::simd::SimdPartialOrd;
#[cfg(feature = "dim2")]
use na::SimdPartialOrd;
#[derive(Copy, Clone, Debug)]
pub(crate) struct VelocityGroundConstraintElementPart {
pub(crate) struct VelocityGroundConstraintTangentPart {
pub gcross2: [AngVector<Real>; DIM - 1],
pub rhs: [Real; DIM - 1],
#[cfg(feature = "dim2")]
pub impulse: [Real; DIM - 1],
#[cfg(feature = "dim3")]
pub impulse: na::Vector2<Real>,
pub r: [Real; DIM - 1],
}
#[cfg(not(target_arch = "wasm32"))]
impl VelocityGroundConstraintTangentPart {
fn zero() -> Self {
Self {
gcross2: [na::zero(); DIM - 1],
rhs: [0.0; DIM - 1],
#[cfg(feature = "dim2")]
impulse: [0.0; DIM - 1],
#[cfg(feature = "dim3")]
impulse: na::zero(),
r: [0.0; DIM - 1],
}
}
}
#[derive(Copy, Clone, Debug)]
pub(crate) struct VelocityGroundConstraintNormalPart {
pub gcross2: AngVector<Real>,
pub rhs: Real,
pub impulse: Real,
@@ -15,7 +44,7 @@ pub(crate) struct VelocityGroundConstraintElementPart {
}
#[cfg(not(target_arch = "wasm32"))]
impl VelocityGroundConstraintElementPart {
impl VelocityGroundConstraintNormalPart {
fn zero() -> Self {
Self {
gcross2: na::zero(),
@@ -28,16 +57,16 @@ impl VelocityGroundConstraintElementPart {
#[derive(Copy, Clone, Debug)]
pub(crate) struct VelocityGroundConstraintElement {
pub normal_part: VelocityGroundConstraintElementPart,
pub tangent_part: [VelocityGroundConstraintElementPart; DIM - 1],
pub normal_part: VelocityGroundConstraintNormalPart,
pub tangent_part: VelocityGroundConstraintTangentPart,
}
#[cfg(not(target_arch = "wasm32"))]
impl VelocityGroundConstraintElement {
pub fn zero() -> Self {
Self {
normal_part: VelocityGroundConstraintElementPart::zero(),
tangent_part: [VelocityGroundConstraintElementPart::zero(); DIM - 1],
normal_part: VelocityGroundConstraintNormalPart::zero(),
tangent_part: VelocityGroundConstraintTangentPart::zero(),
}
}
}
@@ -45,6 +74,10 @@ impl VelocityGroundConstraintElement {
#[derive(Copy, Clone, Debug)]
pub(crate) struct VelocityGroundConstraint {
pub dir1: Vector<Real>, // Non-penetration force direction for the first body.
#[cfg(feature = "dim3")]
pub tangent1: Vector<Real>, // One of the friction force directions.
#[cfg(feature = "dim3")]
pub tangent_rot1: na::UnitComplex<Real>, // Orientation of the tangent basis wrt. the reference basis.
pub im2: Real,
pub limit: Real,
pub mj_lambda2: usize,
@@ -77,6 +110,12 @@ impl VelocityGroundConstraint {
(-manifold.data.normal, 1.0)
};
#[cfg(feature = "dim2")]
let tangents1 = force_dir1.orthonormal_basis();
#[cfg(feature = "dim3")]
let (tangents1, tangent_rot1) =
super::compute_tangent_contact_directions(&force_dir1, &rb1.linvel, &rb2.linvel);
let mj_lambda2 = rb2.active_set_offset;
let warmstart_coeff = manifold.data.warmstart_multiplier * params.warmstart_coeff;
@@ -89,6 +128,10 @@ impl VelocityGroundConstraint {
#[cfg(not(target_arch = "wasm32"))]
let mut constraint = VelocityGroundConstraint {
dir1: force_dir1,
#[cfg(feature = "dim3")]
tangent1: tangents1[0],
#[cfg(feature = "dim3")]
tangent_rot1,
elements: [VelocityGroundConstraintElement::zero(); MAX_MANIFOLD_POINTS],
im2: rb2.effective_inv_mass,
limit: 0.0,
@@ -166,7 +209,7 @@ impl VelocityGroundConstraint {
rhs *= is_bouncy + is_resting * params.velocity_solve_fraction;
rhs += is_resting * velocity_based_erp_inv_dt * manifold_point.dist.min(0.0);
constraint.elements[k].normal_part = VelocityGroundConstraintElementPart {
constraint.elements[k].normal_part = VelocityGroundConstraintNormalPart {
gcross2,
rhs,
impulse: manifold_point.data.impulse * warmstart_coeff,
@@ -176,7 +219,12 @@ impl VelocityGroundConstraint {
// Tangent parts.
{
let tangents1 = force_dir1.orthonormal_basis();
#[cfg(feature = "dim3")]
let impulse =
tangent_rot1 * manifold_points[k].data.tangent_impulse * warmstart_coeff;
#[cfg(feature = "dim2")]
let impulse = [manifold_points[k].data.tangent_impulse * warmstart_coeff];
constraint.elements[k].tangent_part.impulse = impulse;
for j in 0..DIM - 1 {
let gcross2 = rb2
@@ -186,18 +234,10 @@ impl VelocityGroundConstraint {
let rhs = (vel1 - vel2
+ flipped_multiplier * manifold_point.tangent_velocity)
.dot(&tangents1[j]);
#[cfg(feature = "dim2")]
let impulse = manifold_points[k].data.tangent_impulse * warmstart_coeff;
#[cfg(feature = "dim3")]
let impulse = manifold_points[k].data.tangent_impulse[j] * warmstart_coeff;
constraint.elements[k].tangent_part[j] =
VelocityGroundConstraintElementPart {
gcross2,
rhs,
impulse,
r,
};
constraint.elements[k].tangent_part.gcross2[j] = gcross2;
constraint.elements[k].tangent_part.rhs[j] = rhs;
constraint.elements[k].tangent_part.r[j] = r;
}
}
}
@@ -214,6 +254,9 @@ impl VelocityGroundConstraint {
pub fn warmstart(&self, mj_lambdas: &mut [DeltaVel<Real>]) {
let mut mj_lambda2 = DeltaVel::zero();
#[cfg(feature = "dim3")]
let tangents1 = [self.tangent1, self.dir1.cross(&self.tangent1)];
#[cfg(feature = "dim2")]
let tangents1 = self.dir1.orthonormal_basis();
for i in 0..self.num_contacts as usize {
@@ -222,9 +265,9 @@ impl VelocityGroundConstraint {
mj_lambda2.angular += elt.gcross2 * elt.impulse;
for j in 0..DIM - 1 {
let elt = &self.elements[i].tangent_part[j];
mj_lambda2.linear += tangents1[j] * (-self.im2 * elt.impulse);
mj_lambda2.angular += elt.gcross2 * elt.impulse;
let elt = &self.elements[i].tangent_part;
mj_lambda2.linear += tangents1[j] * (-self.im2 * elt.impulse[j]);
mj_lambda2.angular += elt.gcross2[j] * elt.impulse[j];
}
}
@@ -236,23 +279,51 @@ impl VelocityGroundConstraint {
let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
// Solve friction.
#[cfg(feature = "dim3")]
let bitangent1 = self.dir1.cross(&self.tangent1);
#[cfg(feature = "dim2")]
let tangents1 = self.dir1.orthonormal_basis();
#[cfg(feature = "dim2")]
for i in 0..self.num_contacts as usize {
for j in 0..DIM - 1 {
let normal_elt = &self.elements[i].normal_part;
let elt = &mut self.elements[i].tangent_part[j];
let dimpulse = -tangents1[j].dot(&mj_lambda2.linear)
+ elt.gcross2.gdot(mj_lambda2.angular)
+ elt.rhs;
let limit = self.limit * normal_elt.impulse;
let new_impulse = (elt.impulse - elt.r * dimpulse).simd_clamp(-limit, limit);
let dlambda = new_impulse - elt.impulse;
elt.impulse = new_impulse;
let normal_elt = &self.elements[i].normal_part;
let elt = &mut self.elements[i].tangent_part;
let dimpulse = -tangents1[0].dot(&mj_lambda2.linear)
+ elt.gcross2[0].gdot(mj_lambda2.angular)
+ elt.rhs[0];
let limit = self.limit * normal_elt.impulse;
let new_impulse = (elt.impulse[0] - elt.r[0] * dimpulse).simd_clamp(-limit, limit);
let dlambda = new_impulse - elt.impulse[0];
elt.impulse[0] = new_impulse;
mj_lambda2.linear += tangents1[j] * (-self.im2 * dlambda);
mj_lambda2.angular += elt.gcross2 * dlambda;
}
mj_lambda2.linear += tangents1[0] * (-self.im2 * dlambda);
mj_lambda2.angular += elt.gcross2[0] * dlambda;
}
#[cfg(feature = "dim3")]
for i in 0..self.num_contacts as usize {
let limit = self.limit * self.elements[i].normal_part.impulse;
let elts = &mut self.elements[i].tangent_part;
let dimpulse_0 = -self.tangent1.dot(&mj_lambda2.linear)
+ elts.gcross2[0].gdot(mj_lambda2.angular)
+ elts.rhs[0];
let dimpulse_1 = -bitangent1.dot(&mj_lambda2.linear)
+ elts.gcross2[1].gdot(mj_lambda2.angular)
+ elts.rhs[1];
let new_impulse = na::Vector2::new(
elts.impulse[0] - elts.r[0] * dimpulse_0,
elts.impulse[1] - elts.r[1] * dimpulse_1,
);
let new_impulse = new_impulse.cap_magnitude(limit);
let dlambda = new_impulse - elts.impulse;
elts.impulse = new_impulse;
mj_lambda2.linear +=
self.tangent1 * (-self.im2 * dlambda[0]) + bitangent1 * (-self.im2 * dlambda[1]);
mj_lambda2.angular += elts.gcross2[0] * dlambda[0] + elts.gcross2[1] * dlambda[1];
}
// Solve penetration.
@@ -281,14 +352,13 @@ impl VelocityGroundConstraint {
active_contact.data.impulse = self.elements[k].normal_part.impulse;
#[cfg(feature = "dim2")]
{
active_contact.data.tangent_impulse = self.elements[k].tangent_part[0].impulse;
active_contact.data.tangent_impulse = self.elements[k].tangent_part.impulse[0];
}
#[cfg(feature = "dim3")]
{
active_contact.data.tangent_impulse = [
self.elements[k].tangent_part[0].impulse,
self.elements[k].tangent_part[1].impulse,
];
active_contact.data.tangent_impulse = self
.tangent_rot1
.inverse_transform_vector(&self.elements[k].tangent_part.impulse);
}
}
}