First public release of Rapier.v0.1.0

1 files changed, 294 insertions, 0 deletions

diff --git a/src/dynamics/solver/joint_constraint/revolute_velocity_constraint.rs b/src/dynamics/solver/joint_constraint/revolute_velocity_constraint.rs
new file mode 100644
index 0000000..caf8e40
--- /dev/null
+++ b/src/dynamics/solver/joint_constraint/revolute_velocity_constraint.rs
@@ -0,0 +1,294 @@
+use crate::dynamics::solver::DeltaVel;
+use crate::dynamics::{
+    IntegrationParameters, JointGraphEdge, JointIndex, JointParams, RevoluteJoint, RigidBody,
+};
+use crate::math::{AngularInertia, Vector};
+use crate::utils::{WAngularInertia, WCross, WCrossMatrix};
+use na::{Cholesky, Matrix3x2, Matrix5, Vector5, U2, U3};
+
+#[derive(Debug)]
+pub(crate) struct RevoluteVelocityConstraint {
+    mj_lambda1: usize,
+    mj_lambda2: usize,
+
+    joint_id: JointIndex,
+
+    r1: Vector<f32>,
+    r2: Vector<f32>,
+
+    inv_lhs: Matrix5<f32>,
+    rhs: Vector5<f32>,
+    impulse: Vector5<f32>,
+
+    basis1: Matrix3x2<f32>,
+
+    im1: f32,
+    im2: f32,
+
+    ii1_sqrt: AngularInertia<f32>,
+    ii2_sqrt: AngularInertia<f32>,
+}
+
+impl RevoluteVelocityConstraint {
+    pub fn from_params(
+        params: &IntegrationParameters,
+        joint_id: JointIndex,
+        rb1: &RigidBody,
+        rb2: &RigidBody,
+        cparams: &RevoluteJoint,
+    ) -> Self {
+        // Linear part.
+        let anchor1 = rb1.position * cparams.local_anchor1;
+        let anchor2 = rb2.position * cparams.local_anchor2;
+        let basis1 = Matrix3x2::from_columns(&[
+            rb1.position * cparams.basis1[0],
+            rb1.position * cparams.basis1[1],
+        ]);
+
+        //        let r21 = Rotation::rotation_between_axis(&axis1, &axis2)
+        //            .unwrap_or(Rotation::identity())
+        //            .to_rotation_matrix()
+        //            .into_inner();
+        //        let basis2 = r21 * basis1;
+        // NOTE: to simplify, we use basis2 = basis1.
+        // Though we may want to test if that does not introduce any instability.
+        let im1 = rb1.mass_properties.inv_mass;
+        let im2 = rb2.mass_properties.inv_mass;
+
+        let ii1 = rb1.world_inv_inertia_sqrt.squared();
+        let r1 = anchor1 - rb1.world_com;
+        let r1_mat = r1.gcross_matrix();
+
+        let ii2 = rb2.world_inv_inertia_sqrt.squared();
+        let r2 = anchor2 - rb2.world_com;
+        let r2_mat = r2.gcross_matrix();
+
+        let mut lhs = Matrix5::zeros();
+        let lhs00 =
+            ii2.quadform(&r2_mat).add_diagonal(im2) + ii1.quadform(&r1_mat).add_diagonal(im1);
+        let lhs10 = basis1.tr_mul(&(ii2 * r2_mat + ii1 * r1_mat));
+        let lhs11 = (ii1 + ii2).quadform3x2(&basis1).into_matrix();
+
+        // Note that cholesky won't read the upper-right part
+        // of lhs so we don't have to fill it.
+        lhs.fixed_slice_mut::<U3, U3>(0, 0)
+            .copy_from(&lhs00.into_matrix());
+        lhs.fixed_slice_mut::<U2, U3>(3, 0).copy_from(&lhs10);
+        lhs.fixed_slice_mut::<U2, U2>(3, 3).copy_from(&lhs11);
+
+        let inv_lhs = Cholesky::new_unchecked(lhs).inverse();
+
+        let lin_rhs = rb2.linvel + rb2.angvel.gcross(r2) - rb1.linvel - rb1.angvel.gcross(r1);
+        let ang_rhs = basis1.tr_mul(&(rb2.angvel - rb1.angvel));
+        let rhs = Vector5::new(lin_rhs.x, lin_rhs.y, lin_rhs.z, ang_rhs.x, ang_rhs.y);
+
+        RevoluteVelocityConstraint {
+            joint_id,
+            mj_lambda1: rb1.active_set_offset,
+            mj_lambda2: rb2.active_set_offset,
+            im1,
+            ii1_sqrt: rb1.world_inv_inertia_sqrt,
+            basis1,
+            im2,
+            ii2_sqrt: rb2.world_inv_inertia_sqrt,
+            impulse: cparams.impulse * params.warmstart_coeff,
+            inv_lhs,
+            rhs,
+            r1,
+            r2,
+        }
+    }
+
+    pub fn warmstart(&self, mj_lambdas: &mut [DeltaVel<f32>]) {
+        let mut mj_lambda1 = mj_lambdas[self.mj_lambda1 as usize];
+        let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
+
+        let lin_impulse = self.impulse.fixed_rows::<U3>(0).into_owned();
+        let ang_impulse = self.basis1 * self.impulse.fixed_rows::<U2>(3).into_owned();
+
+        mj_lambda1.linear += self.im1 * lin_impulse;
+        mj_lambda1.angular += self
+            .ii1_sqrt
+            .transform_vector(ang_impulse + self.r1.gcross(lin_impulse));
+
+        mj_lambda2.linear -= self.im2 * lin_impulse;
+        mj_lambda2.angular -= self
+            .ii2_sqrt
+            .transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
+
+        mj_lambdas[self.mj_lambda1 as usize] = mj_lambda1;
+        mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
+    }
+
+    pub fn solve(&mut self, mj_lambdas: &mut [DeltaVel<f32>]) {
+        let mut mj_lambda1 = mj_lambdas[self.mj_lambda1 as usize];
+        let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
+
+        let ang_vel1 = self.ii1_sqrt.transform_vector(mj_lambda1.angular);
+        let ang_vel2 = self.ii2_sqrt.transform_vector(mj_lambda2.angular);
+        let lin_dvel = mj_lambda2.linear + ang_vel2.gcross(self.r2)
+            - mj_lambda1.linear
+            - ang_vel1.gcross(self.r1);
+        let ang_dvel = self.basis1.tr_mul(&(ang_vel2 - ang_vel1));
+        let rhs =
+            Vector5::new(lin_dvel.x, lin_dvel.y, lin_dvel.z, ang_dvel.x, ang_dvel.y) + self.rhs;
+        let impulse = self.inv_lhs * rhs;
+        self.impulse += impulse;
+        let lin_impulse = impulse.fixed_rows::<U3>(0).into_owned();
+        let ang_impulse = self.basis1 * impulse.fixed_rows::<U2>(3).into_owned();
+
+        mj_lambda1.linear += self.im1 * lin_impulse;
+        mj_lambda1.angular += self
+            .ii1_sqrt
+            .transform_vector(ang_impulse + self.r1.gcross(lin_impulse));
+
+        mj_lambda2.linear -= self.im2 * lin_impulse;
+        mj_lambda2.angular -= self
+            .ii2_sqrt
+            .transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
+
+        mj_lambdas[self.mj_lambda1 as usize] = mj_lambda1;
+        mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
+    }
+
+    pub fn writeback_impulses(&self, joints_all: &mut [JointGraphEdge]) {
+        let joint = &mut joints_all[self.joint_id].weight;
+        if let JointParams::RevoluteJoint(revolute) = &mut joint.params {
+            revolute.impulse = self.impulse;
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct RevoluteVelocityGroundConstraint {
+    mj_lambda2: usize,
+
+    joint_id: JointIndex,
+
+    r2: Vector<f32>,
+
+    inv_lhs: Matrix5<f32>,
+    rhs: Vector5<f32>,
+    impulse: Vector5<f32>,
+
+    basis1: Matrix3x2<f32>,
+
+    im2: f32,
+
+    ii2_sqrt: AngularInertia<f32>,
+}
+
+impl RevoluteVelocityGroundConstraint {
+    pub fn from_params(
+        params: &IntegrationParameters,
+        joint_id: JointIndex,
+        rb1: &RigidBody,
+        rb2: &RigidBody,
+        cparams: &RevoluteJoint,
+        flipped: bool,
+    ) -> Self {
+        let anchor2;
+        let anchor1;
+        let basis1;
+
+        if flipped {
+            anchor1 = rb1.position * cparams.local_anchor2;
+            anchor2 = rb2.position * cparams.local_anchor1;
+            basis1 = Matrix3x2::from_columns(&[
+                rb1.position * cparams.basis2[0],
+                rb1.position * cparams.basis2[1],
+            ]);
+        } else {
+            anchor1 = rb1.position * cparams.local_anchor1;
+            anchor2 = rb2.position * cparams.local_anchor2;
+            basis1 = Matrix3x2::from_columns(&[
+                rb1.position * cparams.basis1[0],
+                rb1.position * cparams.basis1[1],
+            ]);
+        };
+
+        //        let r21 = Rotation::rotation_between_axis(&axis1, &axis2)
+        //            .unwrap_or(Rotation::identity())
+        //            .to_rotation_matrix()
+        //            .into_inner();
+        //        let basis2 = /*r21 * */ basis1;
+        let im2 = rb2.mass_properties.inv_mass;
+        let ii2 = rb2.world_inv_inertia_sqrt.squared();
+        let r1 = anchor1 - rb1.world_com;
+        let r2 = anchor2 - rb2.world_com;
+        let r2_mat = r2.gcross_matrix();
+
+        let mut lhs = Matrix5::zeros();
+        let lhs00 = ii2.quadform(&r2_mat).add_diagonal(im2);
+        let lhs10 = basis1.tr_mul(&(ii2 * r2_mat));
+        let lhs11 = ii2.quadform3x2(&basis1).into_matrix();
+
+        // Note that cholesky won't read the upper-right part
+        // of lhs so we don't have to fill it.
+        lhs.fixed_slice_mut::<U3, U3>(0, 0)
+            .copy_from(&lhs00.into_matrix());
+        lhs.fixed_slice_mut::<U2, U3>(3, 0).copy_from(&lhs10);
+        lhs.fixed_slice_mut::<U2, U2>(3, 3).copy_from(&lhs11);
+
+        let inv_lhs = Cholesky::new_unchecked(lhs).inverse();
+
+        let lin_rhs = rb2.linvel + rb2.angvel.gcross(r2) - rb1.linvel - rb1.angvel.gcross(r1);
+        let ang_rhs = basis1.tr_mul(&(rb2.angvel - rb1.angvel));
+        let rhs = Vector5::new(lin_rhs.x, lin_rhs.y, lin_rhs.z, ang_rhs.x, ang_rhs.y);
+
+        RevoluteVelocityGroundConstraint {
+            joint_id,
+            mj_lambda2: rb2.active_set_offset,
+            im2,
+            ii2_sqrt: rb2.world_inv_inertia_sqrt,
+            impulse: cparams.impulse * params.warmstart_coeff,
+            basis1,
+            inv_lhs,
+            rhs,
+            r2,
+        }
+    }
+
+    pub fn warmstart(&self, mj_lambdas: &mut [DeltaVel<f32>]) {
+        let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
+
+        let lin_impulse = self.impulse.fixed_rows::<U3>(0).into_owned();
+        let ang_impulse = self.basis1 * self.impulse.fixed_rows::<U2>(3).into_owned();
+
+        mj_lambda2.linear -= self.im2 * lin_impulse;
+        mj_lambda2.angular -= self
+            .ii2_sqrt
+            .transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
+
+        mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
+    }
+
+    pub fn solve(&mut self, mj_lambdas: &mut [DeltaVel<f32>]) {
+        let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
+
+        let ang_vel2 = self.ii2_sqrt.transform_vector(mj_lambda2.angular);
+        let lin_dvel = mj_lambda2.linear + ang_vel2.gcross(self.r2);
+        let ang_dvel = self.basis1.tr_mul(&ang_vel2);
+        let rhs =
+            Vector5::new(lin_dvel.x, lin_dvel.y, lin_dvel.z, ang_dvel.x, ang_dvel.y) + self.rhs;
+        let impulse = self.inv_lhs * rhs;
+        self.impulse += impulse;
+        let lin_impulse = impulse.fixed_rows::<U3>(0).into_owned();
+        let ang_impulse = self.basis1 * impulse.fixed_rows::<U2>(3).into_owned();
+
+        mj_lambda2.linear -= self.im2 * lin_impulse;
+        mj_lambda2.angular -= self
+            .ii2_sqrt
+            .transform_vector(ang_impulse + self.r2.gcross(lin_impulse));
+
+        mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
+    }
+
+    // FIXME: duplicated code with the non-ground constraint.
+    pub fn writeback_impulses(&self, joints_all: &mut [JointGraphEdge]) {
+        let joint = &mut joints_all[self.joint_id].weight;
+        if let JointParams::RevoluteJoint(revolute) = &mut joint.params {
+            revolute.impulse = self.impulse;
+        }
+    }
+}