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use crate::dynamics::solver::PositionGroundConstraint;
#[cfg(feature = "simd-is-enabled")]
use crate::dynamics::solver::{WPositionConstraint, WPositionGroundConstraint};
use crate::dynamics::{IntegrationParameters, RigidBodySet};
use crate::geometry::ContactManifold;
use crate::math::{
AngularInertia, Isometry, Point, Real, Rotation, Translation, Vector, MAX_MANIFOLD_POINTS,
};
use crate::utils::{WAngularInertia, WCross, WDot};
pub(crate) enum AnyPositionConstraint {
#[cfg(feature = "simd-is-enabled")]
GroupedGround(WPositionGroundConstraint),
NonGroupedGround(PositionGroundConstraint),
#[cfg(feature = "simd-is-enabled")]
GroupedNonGround(WPositionConstraint),
NonGroupedNonGround(PositionConstraint),
#[allow(dead_code)] // The Empty variant is only used with parallel code.
Empty,
}
impl AnyPositionConstraint {
pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<Real>]) {
match self {
#[cfg(feature = "simd-is-enabled")]
AnyPositionConstraint::GroupedGround(c) => c.solve(params, positions),
AnyPositionConstraint::NonGroupedGround(c) => c.solve(params, positions),
#[cfg(feature = "simd-is-enabled")]
AnyPositionConstraint::GroupedNonGround(c) => c.solve(params, positions),
AnyPositionConstraint::NonGroupedNonGround(c) => c.solve(params, positions),
AnyPositionConstraint::Empty => unreachable!(),
}
}
}
pub(crate) struct PositionConstraint {
pub rb1: usize,
pub rb2: usize,
// NOTE: the points are relative to the center of masses.
pub local_p1: [Point<Real>; MAX_MANIFOLD_POINTS],
pub local_p2: [Point<Real>; MAX_MANIFOLD_POINTS],
pub dists: [Real; MAX_MANIFOLD_POINTS],
pub local_n1: Vector<Real>,
pub num_contacts: u8,
pub im1: Real,
pub im2: Real,
pub ii1: AngularInertia<Real>,
pub ii2: AngularInertia<Real>,
pub erp: Real,
pub max_linear_correction: Real,
}
impl PositionConstraint {
pub fn generate(
params: &IntegrationParameters,
manifold: &ContactManifold,
bodies: &RigidBodySet,
out_constraints: &mut Vec<AnyPositionConstraint>,
push: bool,
) {
let rb1 = &bodies[manifold.data.body_pair.body1];
let rb2 = &bodies[manifold.data.body_pair.body2];
for (l, manifold_points) in manifold
.data
.solver_contacts
.chunks(MAX_MANIFOLD_POINTS)
.enumerate()
{
let mut local_p1 = [Point::origin(); MAX_MANIFOLD_POINTS];
let mut local_p2 = [Point::origin(); MAX_MANIFOLD_POINTS];
let mut dists = [0.0; MAX_MANIFOLD_POINTS];
for l in 0..manifold_points.len() {
local_p1[l] = rb1
.position
.inverse_transform_point(&manifold_points[l].point);
local_p2[l] = rb2
.position
.inverse_transform_point(&manifold_points[l].point);
dists[l] = manifold_points[l].dist;
}
let constraint = PositionConstraint {
rb1: rb1.active_set_offset,
rb2: rb2.active_set_offset,
local_p1,
local_p2,
local_n1: rb1.position.inverse_transform_vector(&manifold.data.normal),
dists,
im1: rb1.effective_inv_mass,
im2: rb2.effective_inv_mass,
ii1: rb1.effective_world_inv_inertia_sqrt.squared(),
ii2: rb2.effective_world_inv_inertia_sqrt.squared(),
num_contacts: manifold_points.len() as u8,
erp: params.erp,
max_linear_correction: params.max_linear_correction,
};
if push {
out_constraints.push(AnyPositionConstraint::NonGroupedNonGround(constraint));
} else {
out_constraints[manifold.data.constraint_index + l] =
AnyPositionConstraint::NonGroupedNonGround(constraint);
}
}
}
pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<Real>]) {
// FIXME: can we avoid most of the multiplications by pos1/pos2?
// Compute jacobians.
let mut pos1 = positions[self.rb1];
let mut pos2 = positions[self.rb2];
let allowed_err = params.allowed_linear_error;
for k in 0..self.num_contacts as usize {
let target_dist = -self.dists[k] - allowed_err;
let n1 = pos1 * self.local_n1;
let p1 = pos1 * self.local_p1[k];
let p2 = pos2 * self.local_p2[k];
let dpos = p2 - p1;
let dist = dpos.dot(&n1);
if dist < target_dist {
let p1 = p2 - n1 * dist;
let err = ((dist - target_dist) * self.erp).max(-self.max_linear_correction);
let dp1 = p1.coords - pos1.translation.vector;
let dp2 = p2.coords - pos2.translation.vector;
let gcross1 = dp1.gcross(n1);
let gcross2 = -dp2.gcross(n1);
let ii_gcross1 = self.ii1.transform_vector(gcross1);
let ii_gcross2 = self.ii2.transform_vector(gcross2);
// Compute impulse.
let inv_r =
self.im1 + self.im2 + gcross1.gdot(ii_gcross1) + gcross2.gdot(ii_gcross2);
let impulse = err / inv_r;
// Apply impulse.
let tra1 = Translation::from(n1 * (impulse * self.im1));
let tra2 = Translation::from(n1 * (-impulse * self.im2));
let rot1 = Rotation::new(ii_gcross1 * impulse);
let rot2 = Rotation::new(ii_gcross2 * impulse);
pos1 = Isometry::from_parts(tra1 * pos1.translation, rot1 * pos1.rotation);
pos2 = Isometry::from_parts(tra2 * pos2.translation, rot2 * pos2.rotation);
}
}
positions[self.rb1] = pos1;
positions[self.rb2] = pos2;
}
}
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