Files
rapier/src/dynamics/solver/generic_velocity_ground_constraint.rs
2022-03-20 21:49:16 +01:00

246 lines
9.1 KiB
Rust

use crate::data::{BundleSet, ComponentSet};
use crate::dynamics::solver::VelocityGroundConstraint;
use crate::dynamics::{
IntegrationParameters, MultibodyJointSet, RigidBodyIds, RigidBodyMassProps, RigidBodyType,
RigidBodyVelocity,
};
use crate::geometry::{ContactManifold, ContactManifoldIndex};
use crate::math::{Point, Real, DIM, MAX_MANIFOLD_POINTS};
use crate::utils::WCross;
use super::{
AnyVelocityConstraint, VelocityGroundConstraintElement, VelocityGroundConstraintNormalPart,
};
#[cfg(feature = "dim2")]
use crate::utils::WBasis;
use na::DVector;
#[derive(Copy, Clone, Debug)]
pub(crate) struct GenericVelocityGroundConstraint {
// We just build the generic constraint on top of the velocity constraint,
// adding some information we can use in the generic case.
pub velocity_constraint: VelocityGroundConstraint,
pub j_id: usize,
pub ndofs2: usize,
}
impl GenericVelocityGroundConstraint {
pub fn generate<Bodies>(
params: &IntegrationParameters,
manifold_id: ContactManifoldIndex,
manifold: &ContactManifold,
bodies: &Bodies,
multibodies: &MultibodyJointSet,
out_constraints: &mut Vec<AnyVelocityConstraint>,
jacobians: &mut DVector<Real>,
jacobian_id: &mut usize,
insert_at: Option<usize>,
) where
Bodies: ComponentSet<RigidBodyIds>
+ ComponentSet<RigidBodyVelocity>
+ ComponentSet<RigidBodyMassProps>
+ ComponentSet<RigidBodyType>,
{
let inv_dt = params.inv_dt();
let erp_inv_dt = params.erp_inv_dt();
let mut handle1 = manifold.data.rigid_body1;
let mut handle2 = manifold.data.rigid_body2;
let flipped = manifold.data.relative_dominance < 0;
let (force_dir1, flipped_multiplier) = if flipped {
std::mem::swap(&mut handle1, &mut handle2);
(manifold.data.normal, -1.0)
} else {
(-manifold.data.normal, 1.0)
};
let (rb_vels1, world_com1) = if let Some(handle1) = handle1 {
let (vels1, mprops1): (&RigidBodyVelocity, &RigidBodyMassProps) =
bodies.index_bundle(handle1.0);
(*vels1, mprops1.world_com)
} else {
(RigidBodyVelocity::zero(), Point::origin())
};
let (rb_vels2, rb_mprops2): (&RigidBodyVelocity, &RigidBodyMassProps) =
bodies.index_bundle(handle2.unwrap().0);
let (mb2, link_id2) = handle2
.and_then(|h| multibodies.rigid_body_link(h))
.map(|m| (&multibodies[m.multibody], m.id))
.unwrap();
let mj_lambda2 = mb2.solver_id;
#[cfg(feature = "dim2")]
let tangents1 = force_dir1.orthonormal_basis();
#[cfg(feature = "dim3")]
let tangents1 = super::compute_tangent_contact_directions(
&force_dir1,
&rb_vels1.linvel,
&rb_vels2.linvel,
);
let multibodies_ndof = mb2.ndofs();
// For each solver contact we generate DIM constraints, and each constraints appends
// the multibodies jacobian and weighted jacobians
let required_jacobian_len =
*jacobian_id + manifold.data.solver_contacts.len() * multibodies_ndof * 2 * DIM;
if jacobians.nrows() < required_jacobian_len && !cfg!(feature = "parallel") {
jacobians.resize_vertically_mut(required_jacobian_len, 0.0);
}
for (_l, manifold_points) in manifold
.data
.solver_contacts
.chunks(MAX_MANIFOLD_POINTS)
.enumerate()
{
let chunk_j_id = *jacobian_id;
let mut constraint = VelocityGroundConstraint {
dir1: force_dir1,
#[cfg(feature = "dim3")]
tangent1: tangents1[0],
elements: [VelocityGroundConstraintElement::zero(); MAX_MANIFOLD_POINTS],
im2: rb_mprops2.effective_inv_mass,
limit: 0.0,
mj_lambda2,
manifold_id,
manifold_contact_id: [0; MAX_MANIFOLD_POINTS],
num_contacts: manifold_points.len() as u8,
};
for k in 0..manifold_points.len() {
let manifold_point = &manifold_points[k];
let dp1 = manifold_point.point - world_com1;
let dp2 = manifold_point.point - rb_mprops2.world_com;
let vel1 = rb_vels1.linvel + rb_vels1.angvel.gcross(dp1);
let vel2 = rb_vels2.linvel + rb_vels2.angvel.gcross(dp2);
constraint.limit = manifold_point.friction;
constraint.manifold_contact_id[k] = manifold_point.contact_id;
// Normal part.
{
let torque_dir2 = dp2.gcross(-force_dir1);
let inv_r2 = mb2
.fill_jacobians(
link_id2,
-force_dir1,
#[cfg(feature = "dim2")]
na::vector!(torque_dir2),
#[cfg(feature = "dim3")]
torque_dir2,
jacobian_id,
jacobians,
)
.0;
let r = crate::utils::inv(inv_r2);
let is_bouncy = manifold_point.is_bouncy() as u32 as Real;
let is_resting = 1.0 - is_bouncy;
let mut rhs_wo_bias = (1.0 + is_bouncy * manifold_point.restitution)
* (vel1 - vel2).dot(&force_dir1);
rhs_wo_bias += manifold_point.dist.max(0.0) * inv_dt;
rhs_wo_bias *= is_bouncy + is_resting;
let rhs_bias =
/* is_resting * */ erp_inv_dt * manifold_point.dist.clamp(-params.max_penetration_correction, 0.0);
constraint.elements[k].normal_part = VelocityGroundConstraintNormalPart {
gcross2: na::zero(), // Unused for generic constraints.
rhs: rhs_wo_bias + rhs_bias,
rhs_wo_bias,
impulse: na::zero(),
r,
};
}
// Tangent parts.
{
constraint.elements[k].tangent_part.impulse = na::zero();
for j in 0..DIM - 1 {
let torque_dir2 = dp2.gcross(-tangents1[j]);
let inv_r2 = mb2
.fill_jacobians(
link_id2,
-tangents1[j],
#[cfg(feature = "dim2")]
na::vector![torque_dir2],
#[cfg(feature = "dim3")]
torque_dir2,
jacobian_id,
jacobians,
)
.0;
let r = crate::utils::inv(inv_r2);
let rhs = (vel1 - vel2
+ flipped_multiplier * manifold_point.tangent_velocity)
.dot(&tangents1[j]);
constraint.elements[k].tangent_part.rhs[j] = rhs;
// FIXME: in 3D, we should take into account gcross[0].dot(gcross[1])
// in lhs. See the corresponding code on the `velocity_constraint.rs`
// file.
constraint.elements[k].tangent_part.r[j] = r;
}
}
}
let constraint = GenericVelocityGroundConstraint {
velocity_constraint: constraint,
j_id: chunk_j_id,
ndofs2: mb2.ndofs(),
};
if let Some(at) = insert_at {
out_constraints[at + _l] =
AnyVelocityConstraint::NongroupedGenericGround(constraint);
} else {
out_constraints.push(AnyVelocityConstraint::NongroupedGenericGround(constraint));
}
}
}
pub fn solve(
&mut self,
cfm_factor: Real,
jacobians: &DVector<Real>,
generic_mj_lambdas: &mut DVector<Real>,
solve_restitution: bool,
solve_friction: bool,
) {
let mj_lambda2 = self.velocity_constraint.mj_lambda2 as usize;
let elements = &mut self.velocity_constraint.elements
[..self.velocity_constraint.num_contacts as usize];
VelocityGroundConstraintElement::generic_solve_group(
cfm_factor,
elements,
jacobians,
self.velocity_constraint.limit,
self.ndofs2,
self.j_id,
mj_lambda2,
generic_mj_lambdas,
solve_restitution,
solve_friction,
);
}
pub fn writeback_impulses(&self, manifolds_all: &mut [&mut ContactManifold]) {
self.velocity_constraint.writeback_impulses(manifolds_all);
}
pub fn remove_bias_from_rhs(&mut self) {
self.velocity_constraint.remove_bias_from_rhs();
}
}