425 lines
16 KiB
Rust
425 lines
16 KiB
Rust
use super::{OneBodyConstraintElement, OneBodyConstraintNormalPart};
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use crate::math::{Point, Real, Vector, DIM, MAX_MANIFOLD_POINTS};
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#[cfg(feature = "dim2")]
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use crate::utils::SimdBasis;
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use crate::utils::{self, SimdAngularInertia, SimdCross, SimdDot, SimdRealCopy};
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use na::Matrix2;
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use parry::math::Isometry;
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use crate::dynamics::integration_parameters::BLOCK_SOLVER_ENABLED;
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use crate::dynamics::solver::solver_body::SolverBody;
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use crate::dynamics::solver::SolverVel;
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use crate::dynamics::{IntegrationParameters, MultibodyJointSet, RigidBodySet, RigidBodyVelocity};
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use crate::geometry::{ContactManifold, ContactManifoldIndex};
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// TODO: move this struct somewhere else.
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#[derive(Copy, Clone, Debug)]
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pub struct ContactPointInfos<N: SimdRealCopy> {
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pub tangent_vel: Vector<N>,
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pub local_p1: Point<N>,
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pub local_p2: Point<N>,
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pub dist: N,
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pub normal_rhs_wo_bias: N,
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}
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impl<N: SimdRealCopy> Default for ContactPointInfos<N> {
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fn default() -> Self {
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Self {
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tangent_vel: Vector::zeros(),
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local_p1: Point::origin(),
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local_p2: Point::origin(),
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dist: N::zero(),
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normal_rhs_wo_bias: N::zero(),
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}
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}
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}
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#[derive(Copy, Clone, Debug)]
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pub(crate) struct OneBodyConstraintBuilder {
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// PERF: only store what’s necessary for the bias updates instead of the complete solver body.
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pub rb1: SolverBody,
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pub vels1: RigidBodyVelocity,
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pub infos: [ContactPointInfos<Real>; MAX_MANIFOLD_POINTS],
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}
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impl OneBodyConstraintBuilder {
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pub fn invalid() -> Self {
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Self {
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rb1: SolverBody::default(),
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vels1: RigidBodyVelocity::zero(),
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infos: [ContactPointInfos::default(); MAX_MANIFOLD_POINTS],
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}
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}
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pub fn generate(
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manifold_id: ContactManifoldIndex,
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manifold: &ContactManifold,
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bodies: &RigidBodySet,
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out_builders: &mut [OneBodyConstraintBuilder],
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out_constraints: &mut [OneBodyConstraint],
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) {
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let mut handle1 = manifold.data.rigid_body1;
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let mut handle2 = manifold.data.rigid_body2;
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let flipped = manifold.data.relative_dominance < 0;
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let (force_dir1, flipped_multiplier) = if flipped {
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std::mem::swap(&mut handle1, &mut handle2);
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(manifold.data.normal, -1.0)
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} else {
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(-manifold.data.normal, 1.0)
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};
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let (vels1, world_com1) = if let Some(handle1) = handle1 {
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let rb1 = &bodies[handle1];
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(rb1.vels, rb1.mprops.world_com)
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} else {
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(RigidBodyVelocity::zero(), Point::origin())
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};
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let rb1 = handle1
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.map(|h| SolverBody::from(&bodies[h]))
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.unwrap_or_default();
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let rb2 = &bodies[handle2.unwrap()];
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let vels2 = &rb2.vels;
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let mprops2 = &rb2.mprops;
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#[cfg(feature = "dim2")]
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let tangents1 = force_dir1.orthonormal_basis();
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#[cfg(feature = "dim3")]
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let tangents1 =
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super::compute_tangent_contact_directions(&force_dir1, &vels1.linvel, &vels2.linvel);
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let solver_vel2 = rb2.ids.active_set_offset;
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for (l, manifold_points) in manifold
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.data
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.solver_contacts
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.chunks(MAX_MANIFOLD_POINTS)
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.enumerate()
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{
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let builder = &mut out_builders[l];
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let constraint = &mut out_constraints[l];
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builder.rb1 = rb1;
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builder.vels1 = vels1;
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constraint.dir1 = force_dir1;
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constraint.im2 = mprops2.effective_inv_mass;
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constraint.solver_vel2 = solver_vel2;
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constraint.manifold_id = manifold_id;
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constraint.num_contacts = manifold_points.len() as u8;
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#[cfg(feature = "dim3")]
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{
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constraint.tangent1 = tangents1[0];
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}
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for k in 0..manifold_points.len() {
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let manifold_point = &manifold_points[k];
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let dp2 = manifold_point.point - mprops2.world_com;
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let dp1 = manifold_point.point - world_com1;
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let vel1 = vels1.linvel + vels1.angvel.gcross(dp1);
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let vel2 = vels2.linvel + vels2.angvel.gcross(dp2);
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constraint.limit = manifold_point.friction;
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constraint.manifold_contact_id[k] = manifold_point.contact_id;
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// Normal part.
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let normal_rhs_wo_bias;
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{
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let gcross2 = mprops2
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.effective_world_inv_inertia_sqrt
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.transform_vector(dp2.gcross(-force_dir1));
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let projected_lin_mass =
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force_dir1.dot(&mprops2.effective_inv_mass.component_mul(&force_dir1));
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let projected_ang_mass = gcross2.gdot(gcross2);
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let projected_mass = utils::inv(projected_lin_mass + projected_ang_mass);
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let is_bouncy = manifold_point.is_bouncy() as u32 as Real;
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let proj_vel1 = vel1.dot(&force_dir1);
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let proj_vel2 = vel2.dot(&force_dir1);
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let dvel = proj_vel1 - proj_vel2;
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// NOTE: we add proj_vel1 since it’s not accessible through solver_vel.
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normal_rhs_wo_bias =
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proj_vel1 + (is_bouncy * manifold_point.restitution) * dvel;
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constraint.elements[k].normal_part = OneBodyConstraintNormalPart {
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gcross2,
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rhs: na::zero(),
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rhs_wo_bias: na::zero(),
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impulse: manifold_point.warmstart_impulse,
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impulse_accumulator: na::zero(),
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r: projected_mass,
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r_mat_elts: [0.0; 2],
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};
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}
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// Tangent parts.
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{
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constraint.elements[k].tangent_part.impulse =
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manifold_point.warmstart_tangent_impulse;
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for j in 0..DIM - 1 {
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let gcross2 = mprops2
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.effective_world_inv_inertia_sqrt
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.transform_vector(dp2.gcross(-tangents1[j]));
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let r = tangents1[j]
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.dot(&mprops2.effective_inv_mass.component_mul(&tangents1[j]))
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+ gcross2.gdot(gcross2);
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let rhs_wo_bias = (vel1
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+ flipped_multiplier * manifold_point.tangent_velocity)
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.dot(&tangents1[j]);
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constraint.elements[k].tangent_part.gcross2[j] = gcross2;
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constraint.elements[k].tangent_part.rhs_wo_bias[j] = rhs_wo_bias;
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constraint.elements[k].tangent_part.rhs[j] = rhs_wo_bias;
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constraint.elements[k].tangent_part.r[j] = if cfg!(feature = "dim2") {
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utils::inv(r)
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} else {
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r
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};
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}
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#[cfg(feature = "dim3")]
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{
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constraint.elements[k].tangent_part.r[2] = 2.0
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* constraint.elements[k].tangent_part.gcross2[0]
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.gdot(constraint.elements[k].tangent_part.gcross2[1]);
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}
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}
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// Builder.
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{
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let local_p1 = rb1.position.inverse_transform_point(&manifold_point.point);
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let local_p2 = rb2
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.pos
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.position
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.inverse_transform_point(&manifold_point.point);
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let infos = ContactPointInfos {
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local_p1,
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local_p2,
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tangent_vel: flipped_multiplier * manifold_point.tangent_velocity,
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dist: manifold_point.dist,
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normal_rhs_wo_bias,
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};
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builder.infos[k] = infos;
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}
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}
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if BLOCK_SOLVER_ENABLED {
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// Coupling between consecutive pairs.
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for k in 0..manifold_points.len() / 2 {
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let k0 = k * 2;
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let k1 = k * 2 + 1;
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let mut r_mat = Matrix2::zeros();
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let r0 = constraint.elements[k0].normal_part.r;
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let r1 = constraint.elements[k1].normal_part.r;
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r_mat.m12 = force_dir1
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.dot(&mprops2.effective_inv_mass.component_mul(&force_dir1))
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+ constraint.elements[k0]
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.normal_part
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.gcross2
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.gdot(constraint.elements[k1].normal_part.gcross2);
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r_mat.m21 = r_mat.m12;
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r_mat.m11 = utils::inv(r0);
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r_mat.m22 = utils::inv(r1);
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if let Some(inv) = r_mat.try_inverse() {
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constraint.elements[k0].normal_part.r_mat_elts = [inv.m11, inv.m22];
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constraint.elements[k1].normal_part.r_mat_elts = [inv.m12, r_mat.m12];
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} else {
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// If inversion failed, the contacts are redundant.
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// Ignore the one with the smallest depth (it is too late to
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// have the constraint removed from the constraint set, so just
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// set the mass (r) matrix elements to 0.
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constraint.elements[k0].normal_part.r_mat_elts =
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if manifold_points[k0].dist <= manifold_points[k1].dist {
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[r0, 0.0]
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} else {
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[0.0, r1]
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};
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constraint.elements[k1].normal_part.r_mat_elts = [0.0; 2];
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}
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}
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}
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}
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}
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pub fn update(
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&self,
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params: &IntegrationParameters,
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solved_dt: Real,
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bodies: &[SolverBody],
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_multibodies: &MultibodyJointSet,
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constraint: &mut OneBodyConstraint,
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) {
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let rb2 = &bodies[constraint.solver_vel2];
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self.update_with_positions(params, solved_dt, &rb2.position, constraint)
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}
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// TODO: this code is SOOOO similar to TwoBodyConstraint::update.
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// In fact the only differences are types and the `rb1` and ignoring its ccd thickness.
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pub fn update_with_positions(
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&self,
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params: &IntegrationParameters,
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solved_dt: Real,
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rb2_pos: &Isometry<Real>,
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constraint: &mut OneBodyConstraint,
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) {
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let cfm_factor = params.cfm_factor();
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let inv_dt = params.inv_dt();
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let erp_inv_dt = params.erp_inv_dt();
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let all_infos = &self.infos[..constraint.num_contacts as usize];
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let all_elements = &mut constraint.elements[..constraint.num_contacts as usize];
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let rb1 = &self.rb1;
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// Integrate the velocity of the static rigid-body, if it’s kinematic.
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let new_pos1 = self
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.vels1
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.integrate(solved_dt, &rb1.position, &rb1.local_com);
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#[cfg(feature = "dim2")]
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let tangents1 = constraint.dir1.orthonormal_basis();
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#[cfg(feature = "dim3")]
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let tangents1 = [
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constraint.tangent1,
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constraint.dir1.cross(&constraint.tangent1),
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];
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for (info, element) in all_infos.iter().zip(all_elements.iter_mut()) {
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// NOTE: the tangent velocity is equivalent to an additional movement of the first body’s surface.
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let p1 = new_pos1 * info.local_p1 + info.tangent_vel * solved_dt;
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let p2 = rb2_pos * info.local_p2;
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let dist = info.dist + (p1 - p2).dot(&constraint.dir1);
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// Normal part.
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{
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let rhs_wo_bias = info.normal_rhs_wo_bias + dist.max(0.0) * inv_dt;
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let rhs_bias = (erp_inv_dt * (dist + params.allowed_linear_error()))
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.clamp(-params.max_corrective_velocity(), 0.0);
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let new_rhs = rhs_wo_bias + rhs_bias;
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element.normal_part.rhs_wo_bias = rhs_wo_bias;
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element.normal_part.rhs = new_rhs;
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element.normal_part.impulse_accumulator += element.normal_part.impulse;
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element.normal_part.impulse *= params.warmstart_coefficient;
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}
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// Tangent part.
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{
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element.tangent_part.impulse_accumulator += element.tangent_part.impulse;
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element.tangent_part.impulse *= params.warmstart_coefficient;
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for j in 0..DIM - 1 {
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let bias = (p1 - p2).dot(&tangents1[j]) * inv_dt;
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element.tangent_part.rhs[j] = element.tangent_part.rhs_wo_bias[j] + bias;
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}
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}
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}
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constraint.cfm_factor = cfm_factor;
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}
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}
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#[derive(Copy, Clone, Debug)]
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pub(crate) struct OneBodyConstraint {
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pub solver_vel2: usize,
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pub dir1: Vector<Real>, // Non-penetration force direction for the first body.
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#[cfg(feature = "dim3")]
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pub tangent1: Vector<Real>, // One of the friction force directions.
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pub im2: Vector<Real>,
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pub cfm_factor: Real,
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pub limit: Real,
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pub elements: [OneBodyConstraintElement<Real>; MAX_MANIFOLD_POINTS],
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pub manifold_id: ContactManifoldIndex,
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pub manifold_contact_id: [u8; MAX_MANIFOLD_POINTS],
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pub num_contacts: u8,
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}
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impl OneBodyConstraint {
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pub fn invalid() -> Self {
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Self {
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solver_vel2: usize::MAX,
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dir1: Vector::zeros(),
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#[cfg(feature = "dim3")]
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tangent1: Vector::zeros(),
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im2: Vector::zeros(),
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cfm_factor: 0.0,
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limit: 0.0,
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elements: [OneBodyConstraintElement::zero(); MAX_MANIFOLD_POINTS],
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manifold_id: ContactManifoldIndex::MAX,
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manifold_contact_id: [u8::MAX; MAX_MANIFOLD_POINTS],
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num_contacts: u8::MAX,
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}
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}
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pub fn warmstart(&mut self, solver_vels: &mut [SolverVel<Real>]) {
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let mut solver_vel2 = solver_vels[self.solver_vel2];
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OneBodyConstraintElement::warmstart_group(
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&mut self.elements[..self.num_contacts as usize],
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&self.dir1,
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#[cfg(feature = "dim3")]
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&self.tangent1,
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&self.im2,
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&mut solver_vel2,
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);
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solver_vels[self.solver_vel2] = solver_vel2;
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}
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pub fn solve(
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&mut self,
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solver_vels: &mut [SolverVel<Real>],
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solve_normal: bool,
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solve_friction: bool,
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) {
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let mut solver_vel2 = solver_vels[self.solver_vel2];
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OneBodyConstraintElement::solve_group(
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self.cfm_factor,
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&mut self.elements[..self.num_contacts as usize],
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&self.dir1,
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#[cfg(feature = "dim3")]
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&self.tangent1,
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&self.im2,
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self.limit,
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&mut solver_vel2,
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solve_normal,
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solve_friction,
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);
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solver_vels[self.solver_vel2] = solver_vel2;
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}
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// FIXME: duplicated code. This is exactly the same as in the two-body velocity constraint.
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pub fn writeback_impulses(&self, manifolds_all: &mut [&mut ContactManifold]) {
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let manifold = &mut manifolds_all[self.manifold_id];
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for k in 0..self.num_contacts as usize {
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let contact_id = self.manifold_contact_id[k];
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let active_contact = &mut manifold.points[contact_id as usize];
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active_contact.data.warmstart_impulse = self.elements[k].normal_part.impulse;
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active_contact.data.warmstart_tangent_impulse = self.elements[k].tangent_part.impulse;
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active_contact.data.impulse = self.elements[k].normal_part.total_impulse();
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active_contact.data.tangent_impulse = self.elements[k].tangent_part.total_impulse();
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}
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}
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pub fn remove_cfm_and_bias_from_rhs(&mut self) {
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self.cfm_factor = 1.0;
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for elt in &mut self.elements {
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elt.normal_part.rhs = elt.normal_part.rhs_wo_bias;
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elt.tangent_part.rhs = elt.tangent_part.rhs_wo_bias;
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}
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}
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}
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