433 lines
15 KiB
Rust
433 lines
15 KiB
Rust
use crate::dynamics::solver::DeltaVel;
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use crate::dynamics::{
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FixedJoint, IntegrationParameters, JointGraphEdge, JointIndex, JointParams, RigidBody,
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};
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use crate::math::{AngularInertia, Dim, Real, SpacialVector, Vector};
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use crate::utils::{WAngularInertia, WCross, WCrossMatrix};
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#[cfg(feature = "dim2")]
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use na::{Matrix3, Vector3};
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#[cfg(feature = "dim3")]
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use na::{Matrix6, Vector6, U3};
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#[derive(Debug)]
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pub(crate) struct FixedVelocityConstraint {
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mj_lambda1: usize,
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mj_lambda2: usize,
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joint_id: JointIndex,
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impulse: SpacialVector<Real>,
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#[cfg(feature = "dim3")]
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inv_lhs: Matrix6<Real>, // FIXME: replace by Cholesky.
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#[cfg(feature = "dim3")]
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rhs: Vector6<Real>,
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#[cfg(feature = "dim2")]
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inv_lhs: Matrix3<Real>, // FIXME: replace by Cholesky.
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#[cfg(feature = "dim2")]
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rhs: Vector3<Real>,
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im1: Real,
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im2: Real,
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ii1: AngularInertia<Real>,
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ii2: AngularInertia<Real>,
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ii1_sqrt: AngularInertia<Real>,
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ii2_sqrt: AngularInertia<Real>,
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r1: Vector<Real>,
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r2: Vector<Real>,
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}
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impl FixedVelocityConstraint {
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pub fn from_params(
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params: &IntegrationParameters,
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joint_id: JointIndex,
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rb1: &RigidBody,
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rb2: &RigidBody,
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cparams: &FixedJoint,
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) -> Self {
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let anchor1 = rb1.position * cparams.local_anchor1;
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let anchor2 = rb2.position * cparams.local_anchor2;
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let im1 = rb1.effective_inv_mass;
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let im2 = rb2.effective_inv_mass;
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let ii1 = rb1.effective_world_inv_inertia_sqrt.squared();
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let ii2 = rb2.effective_world_inv_inertia_sqrt.squared();
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let r1 = anchor1.translation.vector - rb1.world_com.coords;
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let r2 = anchor2.translation.vector - rb2.world_com.coords;
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let rmat1 = r1.gcross_matrix();
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let rmat2 = r2.gcross_matrix();
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#[allow(unused_mut)] // For 2D
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let mut lhs;
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#[cfg(feature = "dim3")]
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{
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let lhs00 =
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ii1.quadform(&rmat1).add_diagonal(im1) + ii2.quadform(&rmat2).add_diagonal(im2);
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let lhs10 = ii1.transform_matrix(&rmat1) + ii2.transform_matrix(&rmat2);
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let lhs11 = (ii1 + ii2).into_matrix();
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// Note that Cholesky only reads the lower-triangular part of the matrix
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// so we don't need to fill lhs01.
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lhs = Matrix6::zeros();
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lhs.fixed_slice_mut::<U3, U3>(0, 0)
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.copy_from(&lhs00.into_matrix());
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lhs.fixed_slice_mut::<U3, U3>(3, 0).copy_from(&lhs10);
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lhs.fixed_slice_mut::<U3, U3>(3, 3).copy_from(&lhs11);
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}
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// In 2D we just unroll the computation because
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// it's just easier that way.
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#[cfg(feature = "dim2")]
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{
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let m11 = im1 + im2 + rmat1.x * rmat1.x * ii1 + rmat2.x * rmat2.x * ii2;
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let m12 = rmat1.x * rmat1.y * ii1 + rmat2.x * rmat2.y * ii2;
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let m22 = im1 + im2 + rmat1.y * rmat1.y * ii1 + rmat2.y * rmat2.y * ii2;
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let m13 = rmat1.x * ii1 + rmat2.x * ii2;
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let m23 = rmat1.y * ii1 + rmat2.y * ii2;
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let m33 = ii1 + ii2;
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lhs = Matrix3::new(m11, m12, m13, m12, m22, m23, m13, m23, m33)
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}
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// NOTE: we don't use cholesky in 2D because we only have a 3x3 matrix
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// for which a textbook inverse is still efficient.
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#[cfg(feature = "dim2")]
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let inv_lhs = lhs.try_inverse().expect("Singular system.");
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#[cfg(feature = "dim3")]
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let inv_lhs = lhs.cholesky().expect("Singular system.").inverse();
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let lin_dvel = -rb1.linvel - rb1.angvel.gcross(r1) + rb2.linvel + rb2.angvel.gcross(r2);
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let ang_dvel = -rb1.angvel + rb2.angvel;
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#[cfg(feature = "dim2")]
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let mut rhs =
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params.velocity_solve_fraction * Vector3::new(lin_dvel.x, lin_dvel.y, ang_dvel);
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#[cfg(feature = "dim3")]
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let mut rhs = params.velocity_solve_fraction
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* Vector6::new(
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lin_dvel.x, lin_dvel.y, lin_dvel.z, ang_dvel.x, ang_dvel.y, ang_dvel.z,
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);
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if params.velocity_based_erp != 0.0 {
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let error = anchor2 * anchor1.inverse();
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let lin_err = error.translation.vector;
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#[cfg(feature = "dim2")]
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{
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let ang_err = error.rotation.angle();
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rhs += params.velocity_based_erp
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* params.inv_dt()
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* Vector3::new(lin_err.x, lin_err.y, ang_err);
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}
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#[cfg(feature = "dim3")]
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{
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let ang_err = error.rotation.scaled_axis();
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rhs += params.velocity_based_erp
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* params.inv_dt()
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* Vector6::new(
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lin_err.x, lin_err.y, lin_err.z, ang_err.x, ang_err.y, ang_err.z,
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);
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}
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}
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FixedVelocityConstraint {
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joint_id,
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mj_lambda1: rb1.active_set_offset,
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mj_lambda2: rb2.active_set_offset,
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im1,
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im2,
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ii1,
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ii2,
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ii1_sqrt: rb1.effective_world_inv_inertia_sqrt,
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ii2_sqrt: rb2.effective_world_inv_inertia_sqrt,
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impulse: cparams.impulse * params.warmstart_coeff,
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inv_lhs,
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r1,
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r2,
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rhs,
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}
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}
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pub fn warmstart(&self, mj_lambdas: &mut [DeltaVel<Real>]) {
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let mut mj_lambda1 = mj_lambdas[self.mj_lambda1 as usize];
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let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
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let lin_impulse = self.impulse.fixed_rows::<Dim>(0).into_owned();
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#[cfg(feature = "dim2")]
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let ang_impulse = self.impulse[2];
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#[cfg(feature = "dim3")]
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let ang_impulse = self.impulse.fixed_rows::<U3>(3).into_owned();
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mj_lambda1.linear += self.im1 * lin_impulse;
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mj_lambda1.angular += self
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.ii1_sqrt
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.transform_vector(ang_impulse + self.r1.gcross(lin_impulse));
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mj_lambda2.linear -= self.im2 * lin_impulse;
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mj_lambda2.angular -= self
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.ii2_sqrt
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.transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
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mj_lambdas[self.mj_lambda1 as usize] = mj_lambda1;
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mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
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}
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pub fn solve(&mut self, mj_lambdas: &mut [DeltaVel<Real>]) {
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let mut mj_lambda1 = mj_lambdas[self.mj_lambda1 as usize];
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let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
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let ang_vel1 = self.ii1_sqrt.transform_vector(mj_lambda1.angular);
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let ang_vel2 = self.ii2_sqrt.transform_vector(mj_lambda2.angular);
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let dlinvel = -mj_lambda1.linear - ang_vel1.gcross(self.r1)
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+ mj_lambda2.linear
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+ ang_vel2.gcross(self.r2);
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let dangvel = -ang_vel1 + ang_vel2;
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#[cfg(feature = "dim2")]
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let rhs = Vector3::new(dlinvel.x, dlinvel.y, dangvel) + self.rhs;
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#[cfg(feature = "dim3")]
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let rhs = Vector6::new(
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dlinvel.x, dlinvel.y, dlinvel.z, dangvel.x, dangvel.y, dangvel.z,
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) + self.rhs;
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let impulse = self.inv_lhs * rhs;
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self.impulse += impulse;
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let lin_impulse = impulse.fixed_rows::<Dim>(0).into_owned();
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#[cfg(feature = "dim2")]
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let ang_impulse = impulse[2];
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#[cfg(feature = "dim3")]
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let ang_impulse = impulse.fixed_rows::<U3>(3).into_owned();
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mj_lambda1.linear += self.im1 * lin_impulse;
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mj_lambda1.angular += self
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.ii1_sqrt
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.transform_vector(ang_impulse + self.r1.gcross(lin_impulse));
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mj_lambda2.linear -= self.im2 * lin_impulse;
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mj_lambda2.angular -= self
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.ii2_sqrt
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.transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
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mj_lambdas[self.mj_lambda1 as usize] = mj_lambda1;
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mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
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}
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pub fn writeback_impulses(&self, joints_all: &mut [JointGraphEdge]) {
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let joint = &mut joints_all[self.joint_id].weight;
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if let JointParams::FixedJoint(fixed) = &mut joint.params {
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fixed.impulse = self.impulse;
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}
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}
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}
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#[derive(Debug)]
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pub(crate) struct FixedVelocityGroundConstraint {
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mj_lambda2: usize,
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joint_id: JointIndex,
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impulse: SpacialVector<Real>,
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#[cfg(feature = "dim3")]
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inv_lhs: Matrix6<Real>, // FIXME: replace by Cholesky.
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#[cfg(feature = "dim3")]
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rhs: Vector6<Real>,
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#[cfg(feature = "dim2")]
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inv_lhs: Matrix3<Real>, // FIXME: replace by Cholesky.
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#[cfg(feature = "dim2")]
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rhs: Vector3<Real>,
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im2: Real,
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ii2: AngularInertia<Real>,
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ii2_sqrt: AngularInertia<Real>,
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r2: Vector<Real>,
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}
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impl FixedVelocityGroundConstraint {
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pub fn from_params(
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params: &IntegrationParameters,
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joint_id: JointIndex,
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rb1: &RigidBody,
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rb2: &RigidBody,
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cparams: &FixedJoint,
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flipped: bool,
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) -> Self {
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let (anchor1, anchor2) = if flipped {
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(
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rb1.position * cparams.local_anchor2,
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rb2.position * cparams.local_anchor1,
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)
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} else {
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(
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rb1.position * cparams.local_anchor1,
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rb2.position * cparams.local_anchor2,
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)
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};
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let r1 = anchor1.translation.vector - rb1.world_com.coords;
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let im2 = rb2.effective_inv_mass;
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let ii2 = rb2.effective_world_inv_inertia_sqrt.squared();
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let r2 = anchor2.translation.vector - rb2.world_com.coords;
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let rmat2 = r2.gcross_matrix();
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#[allow(unused_mut)] // For 2D.
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let mut lhs;
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#[cfg(feature = "dim3")]
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{
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let lhs00 = ii2.quadform(&rmat2).add_diagonal(im2);
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let lhs10 = ii2.transform_matrix(&rmat2);
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let lhs11 = ii2.into_matrix();
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// Note that Cholesky only reads the lower-triangular part of the matrix
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// so we don't need to fill lhs01.
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lhs = Matrix6::zeros();
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lhs.fixed_slice_mut::<U3, U3>(0, 0)
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.copy_from(&lhs00.into_matrix());
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lhs.fixed_slice_mut::<U3, U3>(3, 0).copy_from(&lhs10);
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lhs.fixed_slice_mut::<U3, U3>(3, 3).copy_from(&lhs11);
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}
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// In 2D we just unroll the computation because
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// it's just easier that way.
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#[cfg(feature = "dim2")]
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{
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let m11 = im2 + rmat2.x * rmat2.x * ii2;
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let m12 = rmat2.x * rmat2.y * ii2;
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let m22 = im2 + rmat2.y * rmat2.y * ii2;
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let m13 = rmat2.x * ii2;
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let m23 = rmat2.y * ii2;
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let m33 = ii2;
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lhs = Matrix3::new(m11, m12, m13, m12, m22, m23, m13, m23, m33)
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}
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#[cfg(feature = "dim2")]
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let inv_lhs = lhs.try_inverse().expect("Singular system.");
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#[cfg(feature = "dim3")]
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let inv_lhs = lhs.cholesky().expect("Singular system.").inverse();
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let lin_dvel = rb2.linvel + rb2.angvel.gcross(r2) - rb1.linvel - rb1.angvel.gcross(r1);
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let ang_dvel = rb2.angvel - rb1.angvel;
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#[cfg(feature = "dim2")]
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let mut rhs =
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params.velocity_solve_fraction * Vector3::new(lin_dvel.x, lin_dvel.y, ang_dvel);
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#[cfg(feature = "dim3")]
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let mut rhs = params.velocity_solve_fraction
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* Vector6::new(
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lin_dvel.x, lin_dvel.y, lin_dvel.z, ang_dvel.x, ang_dvel.y, ang_dvel.z,
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);
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if params.velocity_based_erp != 0.0 {
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// let error = anchor2 * anchor1.inverse();
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// let lin_err = error.translation.vector;
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// let ang_err = error.rotation;
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// Doesn't quite do what it should
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// let target_pos = anchor1.lerp_slerp(
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// &anchor2,
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// params.velocity_based_erp * params.inv_dt(),
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// );
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// let error = target_pos * anchor1.inverse();
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// let lin_err = error.translation.vector;
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let lin_err = anchor2.translation.vector - anchor1.translation.vector;
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let ang_err = anchor2.rotation * anchor1.rotation.inverse();
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#[cfg(feature = "dim2")]
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{
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let ang_err = ang_err.angle();
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rhs += params.velocity_based_erp
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* params.inv_dt()
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* Vector3::new(lin_err.x, lin_err.y, ang_err);
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}
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#[cfg(feature = "dim3")]
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{
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let ang_err = ang_err.scaled_axis();
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rhs += params.velocity_based_erp
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* params.inv_dt()
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* Vector6::new(
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lin_err.x, lin_err.y, lin_err.z, ang_err.x, ang_err.y, ang_err.z,
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);
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}
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}
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FixedVelocityGroundConstraint {
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joint_id,
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mj_lambda2: rb2.active_set_offset,
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im2,
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ii2,
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ii2_sqrt: rb2.effective_world_inv_inertia_sqrt,
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impulse: cparams.impulse * params.warmstart_coeff,
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inv_lhs,
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r2,
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rhs,
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}
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}
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pub fn warmstart(&self, mj_lambdas: &mut [DeltaVel<Real>]) {
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let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
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let lin_impulse = self.impulse.fixed_rows::<Dim>(0).into_owned();
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#[cfg(feature = "dim2")]
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let ang_impulse = self.impulse[2];
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#[cfg(feature = "dim3")]
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let ang_impulse = self.impulse.fixed_rows::<U3>(3).into_owned();
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mj_lambda2.linear -= self.im2 * lin_impulse;
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mj_lambda2.angular -= self
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.ii2_sqrt
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.transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
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mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
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}
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pub fn solve(&mut self, mj_lambdas: &mut [DeltaVel<Real>]) {
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let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
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let ang_vel2 = self.ii2_sqrt.transform_vector(mj_lambda2.angular);
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let dlinvel = mj_lambda2.linear + ang_vel2.gcross(self.r2);
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let dangvel = ang_vel2;
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#[cfg(feature = "dim2")]
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let rhs = Vector3::new(dlinvel.x, dlinvel.y, dangvel) + self.rhs;
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#[cfg(feature = "dim3")]
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let rhs = Vector6::new(
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dlinvel.x, dlinvel.y, dlinvel.z, dangvel.x, dangvel.y, dangvel.z,
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) + self.rhs;
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let impulse = self.inv_lhs * rhs;
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self.impulse += impulse;
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let lin_impulse = impulse.fixed_rows::<Dim>(0).into_owned();
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#[cfg(feature = "dim2")]
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let ang_impulse = impulse[2];
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#[cfg(feature = "dim3")]
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let ang_impulse = impulse.fixed_rows::<U3>(3).into_owned();
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mj_lambda2.linear -= self.im2 * lin_impulse;
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mj_lambda2.angular -= self
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.ii2_sqrt
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.transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
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mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
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}
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// FIXME: duplicated code with the non-ground constraint.
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pub fn writeback_impulses(&self, joints_all: &mut [JointGraphEdge]) {
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let joint = &mut joints_all[self.joint_id].weight;
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if let JointParams::FixedJoint(fixed) = &mut joint.params {
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fixed.impulse = self.impulse;
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}
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}
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}
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