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Merge pull request #114 from EmbarkStudios/split-contacts-2

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Split bouncy and resting contacts (take 2)
This commit is contained in:
Sébastien Crozet
2021-02-18 18:39:52 +01:00
committed by GitHub
parent 9a15838ad5 5e7eedc3fd
commit c650bb1fef
6 changed files with 38 additions and 35 deletions
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7
src/dynamics/integration_parameters.rs
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@@ -27,9 +27,6 @@ pub struct IntegrationParameters {
/// Each cached impulse are multiplied by this coefficient in `[0, 1]`
/// when they are re-used to initialize the solver (default `1.0`).
pub warmstart_coeff: Real,
/// Contacts at points where the involved bodies have a relative
/// velocity smaller than this threshold wont be affected by the restitution force (default: `1.0`).
pub restitution_velocity_threshold: Real,
/// Amount of penetration the engine wont attempt to correct (default: `0.005m`).
pub allowed_linear_error: Real,
/// The maximal distance separating two objects that will generate predictive contacts (default: `0.002`).
@@ -95,7 +92,7 @@ impl IntegrationParameters {
erp: Real,
joint_erp: Real,
warmstart_coeff: Real,
restitution_velocity_threshold: Real,
_restitution_velocity_threshold: Real,
allowed_linear_error: Real,
allowed_angular_error: Real,
max_linear_correction: Real,
@@ -116,7 +113,6 @@ impl IntegrationParameters {
erp,
joint_erp,
warmstart_coeff,
restitution_velocity_threshold,
allowed_linear_error,
allowed_angular_error,
max_linear_correction,
@@ -188,7 +184,6 @@ impl Default for IntegrationParameters {
erp: 0.2,
joint_erp: 0.2,
warmstart_coeff: 1.0,
restitution_velocity_threshold: 1.0,
allowed_linear_error: 0.005,
prediction_distance: 0.002,
allowed_angular_error: 0.001,

11
src/dynamics/solver/velocity_constraint.rs
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@@ -239,13 +239,10 @@ impl VelocityConstraint {
+ gcross1.gdot(gcross1)
+ gcross2.gdot(gcross2));
let mut rhs = (vel1 - vel2).dot(&force_dir1);
if rhs <= -params.restitution_velocity_threshold {
rhs += manifold_point.restitution * rhs
}
rhs += manifold_point.dist.max(0.0) * inv_dt;
let is_bouncy = manifold_point.is_bouncy() as u32 as Real;
let rhs = (1.0 + is_bouncy * manifold_point.restitution)
* (vel1 - vel2).dot(&force_dir1)
+ manifold_point.dist.max(0.0) * inv_dt;
let impulse = manifold_point.data.impulse * warmstart_coeff;

13
src/dynamics/solver/velocity_constraint_wide.rs
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@@ -96,8 +96,6 @@ impl WVelocityConstraint {
let mj_lambda1 = array![|ii| rbs1[ii].active_set_offset; SIMD_WIDTH];
let mj_lambda2 = array![|ii| rbs2[ii].active_set_offset; SIMD_WIDTH];
let restitution_velocity_threshold = SimdReal::splat(params.restitution_velocity_threshold);
let warmstart_multiplier =
SimdReal::from(array![|ii| manifolds[ii].data.warmstart_multiplier; SIMD_WIDTH]);
let warmstart_coeff = warmstart_multiplier * SimdReal::splat(params.warmstart_coeff);
@@ -127,6 +125,9 @@ impl WVelocityConstraint {
SimdReal::from(array![|ii| manifold_points[ii][k].friction; SIMD_WIDTH]);
let restitution =
SimdReal::from(array![|ii| manifold_points[ii][k].restitution; SIMD_WIDTH]);
let is_bouncy = SimdReal::from(
array![|ii| manifold_points[ii][k].is_bouncy() as u32 as Real; SIMD_WIDTH],
);
let point = Point::from(array![|ii| manifold_points[ii][k].point; SIMD_WIDTH]);
let dist = SimdReal::from(array![|ii| manifold_points[ii][k].dist; SIMD_WIDTH]);
@@ -148,11 +149,9 @@ impl WVelocityConstraint {
let r = SimdReal::splat(1.0)
/ (im1 + im2 + gcross1.gdot(gcross1) + gcross2.gdot(gcross2));
let mut rhs = (vel1 - vel2).dot(&force_dir1);
let use_restitution = rhs.simd_le(-restitution_velocity_threshold);
let rhs_with_restitution = rhs + rhs * restitution;
rhs = rhs_with_restitution.select(use_restitution, rhs);
rhs += dist.simd_max(SimdReal::zero()) * inv_dt;
let projected_velocity = (vel1 - vel2).dot(&force_dir1);
let rhs = (SimdReal::splat(1.0) + is_bouncy * restitution) * projected_velocity
+ dist.simd_max(SimdReal::zero()) * inv_dt;
constraint.elements[k].normal_part = WVelocityConstraintElementPart {
gcross1,

13
src/dynamics/solver/velocity_ground_constraint.rs
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@@ -154,15 +154,12 @@ impl VelocityGroundConstraint {
let r = 1.0 / (rb2.effective_inv_mass + gcross2.gdot(gcross2));
let mut rhs = (vel1 - vel2).dot(&force_dir1);
let is_bouncy = manifold_point.is_bouncy() as u32 as Real;
let rhs = (1.0 + is_bouncy * manifold_point.restitution)
* (vel1 - vel2).dot(&force_dir1)
+ manifold_point.dist.max(0.0) * inv_dt;
if rhs <= -params.restitution_velocity_threshold {
rhs += manifold_point.restitution * rhs
}
rhs += manifold_point.dist.max(0.0) * inv_dt;
let impulse = manifold_points[k].data.impulse * warmstart_coeff;
let impulse = manifold_point.data.impulse * warmstart_coeff;
constraint.elements[k].normal_part = VelocityGroundConstraintElementPart {
gcross2,

13
src/dynamics/solver/velocity_ground_constraint_wide.rs
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@@ -95,8 +95,6 @@ impl WVelocityGroundConstraint {
let mj_lambda2 = array![|ii| rbs2[ii].active_set_offset; SIMD_WIDTH];
let restitution_velocity_threshold = SimdReal::splat(params.restitution_velocity_threshold);
let warmstart_multiplier =
SimdReal::from(array![|ii| manifolds[ii].data.warmstart_multiplier; SIMD_WIDTH]);
let warmstart_coeff = warmstart_multiplier * SimdReal::splat(params.warmstart_coeff);
@@ -122,6 +120,9 @@ impl WVelocityGroundConstraint {
SimdReal::from(array![|ii| manifold_points[ii][k].friction; SIMD_WIDTH]);
let restitution =
SimdReal::from(array![|ii| manifold_points[ii][k].restitution; SIMD_WIDTH]);
let is_bouncy = SimdReal::from(
array![|ii| manifold_points[ii][k].is_bouncy() as u32 as Real; SIMD_WIDTH],
);
let point = Point::from(array![|ii| manifold_points[ii][k].point; SIMD_WIDTH]);
let dist = SimdReal::from(array![|ii| manifold_points[ii][k].dist; SIMD_WIDTH]);
@@ -140,11 +141,9 @@ impl WVelocityGroundConstraint {
let gcross2 = ii2.transform_vector(dp2.gcross(-force_dir1));
let r = SimdReal::splat(1.0) / (im2 + gcross2.gdot(gcross2));
let mut rhs = (vel1 - vel2).dot(&force_dir1);
let use_restitution = rhs.simd_le(-restitution_velocity_threshold);
let rhs_with_restitution = rhs + rhs * restitution;
rhs = rhs_with_restitution.select(use_restitution, rhs);
rhs += dist.simd_max(SimdReal::zero()) * inv_dt;
let projected_velocity = (vel1 - vel2).dot(&force_dir1);
let rhs = (SimdReal::splat(1.0) + is_bouncy * restitution) * projected_velocity
+ dist.simd_max(SimdReal::zero()) * inv_dt;
constraint.elements[k].normal_part = WVelocityGroundConstraintElementPart {
gcross2,

16
src/geometry/contact_pair.rs
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@@ -128,6 +128,22 @@ pub struct SolverContact {
pub data: ContactData,
}
impl SolverContact {
/// Should we treat this contact as a bouncy contact?
/// If `true`, use [`Self::restitution`].
pub fn is_bouncy(&self) -> bool {
let is_new = self.data.impulse == 0.0;
if is_new {
// Treat new collisions as bouncing at first, unless we have zero restitution.
self.restitution > 0.0
} else {
// If the contact is still here one step later, it is now a resting contact.
// The exception is very high restitutions, which can never rest
self.restitution >= 1.0
}
}
}
impl Default for ContactManifoldData {
fn default() -> Self {
Self::new(