147 lines
6.3 KiB
Rust
147 lines
6.3 KiB
Rust
use super::AnyPositionConstraint;
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use crate::dynamics::{IntegrationParameters, RigidBodySet};
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use crate::geometry::ContactManifold;
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use crate::math::{
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AngularInertia, Isometry, Point, Real, Rotation, SimdReal, Translation, Vector,
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MAX_MANIFOLD_POINTS, SIMD_WIDTH,
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};
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use crate::utils::{WAngularInertia, WCross, WDot};
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use num::Zero;
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use simba::simd::{SimdBool as _, SimdPartialOrd, SimdValue};
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pub(crate) struct WPositionConstraint {
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pub rb1: [usize; SIMD_WIDTH],
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pub rb2: [usize; SIMD_WIDTH],
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// NOTE: the points are relative to the center of masses.
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pub local_p1: [Point<SimdReal>; MAX_MANIFOLD_POINTS],
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pub local_p2: [Point<SimdReal>; MAX_MANIFOLD_POINTS],
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pub dists: [SimdReal; MAX_MANIFOLD_POINTS],
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pub local_n1: Vector<SimdReal>,
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pub im1: SimdReal,
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pub im2: SimdReal,
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pub ii1: AngularInertia<SimdReal>,
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pub ii2: AngularInertia<SimdReal>,
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pub erp: SimdReal,
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pub max_linear_correction: SimdReal,
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pub num_contacts: u8,
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}
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impl WPositionConstraint {
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pub fn generate(
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params: &IntegrationParameters,
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manifolds: [&ContactManifold; SIMD_WIDTH],
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bodies: &RigidBodySet,
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out_constraints: &mut Vec<AnyPositionConstraint>,
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push: bool,
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) {
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let rbs1 = array![|ii| bodies.get(manifolds[ii].data.body_pair.body1).unwrap(); SIMD_WIDTH];
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let rbs2 = array![|ii| bodies.get(manifolds[ii].data.body_pair.body2).unwrap(); SIMD_WIDTH];
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let im1 = SimdReal::from(array![|ii| rbs1[ii].mass_properties.inv_mass; SIMD_WIDTH]);
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let sqrt_ii1: AngularInertia<SimdReal> =
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AngularInertia::from(array![|ii| rbs1[ii].world_inv_inertia_sqrt; SIMD_WIDTH]);
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let im2 = SimdReal::from(array![|ii| rbs2[ii].mass_properties.inv_mass; SIMD_WIDTH]);
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let sqrt_ii2: AngularInertia<SimdReal> =
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AngularInertia::from(array![|ii| rbs2[ii].world_inv_inertia_sqrt; SIMD_WIDTH]);
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let pos1 = Isometry::from(array![|ii| rbs1[ii].position; SIMD_WIDTH]);
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let pos2 = Isometry::from(array![|ii| rbs2[ii].position; SIMD_WIDTH]);
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let local_n1 = pos1.inverse_transform_vector(&Vector::from(
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array![|ii| manifolds[ii].data.normal; SIMD_WIDTH],
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));
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let rb1 = array![|ii| rbs1[ii].active_set_offset; SIMD_WIDTH];
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let rb2 = array![|ii| rbs2[ii].active_set_offset; SIMD_WIDTH];
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let num_active_contacts = manifolds[0].data.num_active_contacts();
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for l in (0..num_active_contacts).step_by(MAX_MANIFOLD_POINTS) {
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let manifold_points = array![|ii| &manifolds[ii].data.solver_contacts[l..]; SIMD_WIDTH];
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let num_points = manifold_points[0].len().min(MAX_MANIFOLD_POINTS);
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let mut constraint = WPositionConstraint {
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rb1,
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rb2,
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local_p1: [Point::origin(); MAX_MANIFOLD_POINTS],
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local_p2: [Point::origin(); MAX_MANIFOLD_POINTS],
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local_n1,
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dists: [SimdReal::zero(); MAX_MANIFOLD_POINTS],
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im1,
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im2,
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ii1: sqrt_ii1.squared(),
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ii2: sqrt_ii2.squared(),
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erp: SimdReal::splat(params.erp),
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max_linear_correction: SimdReal::splat(params.max_linear_correction),
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num_contacts: num_points as u8,
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};
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for i in 0..num_points {
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let point = Point::from(array![|ii| manifold_points[ii][i].point; SIMD_WIDTH]);
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let dist = SimdReal::from(array![|ii| manifold_points[ii][i].dist; SIMD_WIDTH]);
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constraint.local_p1[i] = pos1.inverse_transform_point(&point);
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constraint.local_p2[i] = pos2.inverse_transform_point(&point);
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constraint.dists[i] = dist;
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}
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if push {
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out_constraints.push(AnyPositionConstraint::GroupedNonGround(constraint));
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} else {
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out_constraints[manifolds[0].data.constraint_index + l / MAX_MANIFOLD_POINTS] =
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AnyPositionConstraint::GroupedNonGround(constraint);
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}
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}
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}
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pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<Real>]) {
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// FIXME: can we avoid most of the multiplications by pos1/pos2?
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// Compute jacobians.
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let mut pos1 = Isometry::from(array![|ii| positions[self.rb1[ii]]; SIMD_WIDTH]);
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let mut pos2 = Isometry::from(array![|ii| positions[self.rb2[ii]]; SIMD_WIDTH]);
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let allowed_err = SimdReal::splat(params.allowed_linear_error);
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for k in 0..self.num_contacts as usize {
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let target_dist = -self.dists[k] - allowed_err;
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let n1 = pos1 * self.local_n1;
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let p1 = pos1 * self.local_p1[k];
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let p2 = pos2 * self.local_p2[k];
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let dpos = p2 - p1;
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let dist = dpos.dot(&n1);
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// NOTE: this condition does not seem to be useful perfomancewise?
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if dist.simd_lt(target_dist).any() {
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// NOTE: only works for the point-point case.
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let p1 = p2 - n1 * dist;
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let err = ((dist - target_dist) * self.erp)
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.simd_clamp(-self.max_linear_correction, SimdReal::zero());
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let dp1 = p1.coords - pos1.translation.vector;
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let dp2 = p2.coords - pos2.translation.vector;
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let gcross1 = dp1.gcross(n1);
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let gcross2 = -dp2.gcross(n1);
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let ii_gcross1 = self.ii1.transform_vector(gcross1);
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let ii_gcross2 = self.ii2.transform_vector(gcross2);
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// Compute impulse.
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let inv_r =
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self.im1 + self.im2 + gcross1.gdot(ii_gcross1) + gcross2.gdot(ii_gcross2);
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let impulse = err / inv_r;
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// Apply impulse.
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pos1.translation = Translation::from(n1 * (impulse * self.im1)) * pos1.translation;
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pos1.rotation = Rotation::new(ii_gcross1 * impulse) * pos1.rotation;
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pos2.translation = Translation::from(n1 * (-impulse * self.im2)) * pos2.translation;
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pos2.rotation = Rotation::new(ii_gcross2 * impulse) * pos2.rotation;
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}
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}
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for ii in 0..SIMD_WIDTH {
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positions[self.rb1[ii]] = pos1.extract(ii);
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}
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for ii in 0..SIMD_WIDTH {
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positions[self.rb2[ii]] = pos2.extract(ii);
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}
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}
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}
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