feat: implement new "small-steps" solver + joint improvements

1 files changed, 0 insertions, 281 deletions

diff --git a/src/dynamics/solver/velocity_ground_constraint.rs b/src/dynamics/solver/velocity_ground_constraint.rs
deleted file mode 100644
index 83bbd7e..0000000
--- a/src/dynamics/solver/velocity_ground_constraint.rs
+++ /dev/null
@@ -1,281 +0,0 @@
-use super::{
-    AnyVelocityConstraint, DeltaVel, VelocityGroundConstraintElement,
-    VelocityGroundConstraintNormalPart,
-};
-use crate::math::{Point, Real, Vector, DIM, MAX_MANIFOLD_POINTS};
-#[cfg(feature = "dim2")]
-use crate::utils::WBasis;
-use crate::utils::{self, WAngularInertia, WCross, WDot};
-
-use crate::dynamics::{IntegrationParameters, RigidBodySet, RigidBodyVelocity};
-use crate::geometry::{ContactManifold, ContactManifoldIndex};
-
-#[derive(Copy, Clone, Debug)]
-pub(crate) struct VelocityGroundConstraint {
-    pub mj_lambda2: usize,
-    pub dir1: Vector<Real>, // Non-penetration force direction for the first body.
-    #[cfg(feature = "dim3")]
-    pub tangent1: Vector<Real>, // One of the friction force directions.
-    pub im2: Vector<Real>,
-    pub cfm_factor: Real,
-    pub limit: Real,
-    pub elements: [VelocityGroundConstraintElement<Real>; MAX_MANIFOLD_POINTS],
-
-    pub manifold_id: ContactManifoldIndex,
-    pub manifold_contact_id: [u8; MAX_MANIFOLD_POINTS],
-    pub num_contacts: u8,
-}
-
-impl VelocityGroundConstraint {
-    pub fn generate(
-        params: &IntegrationParameters,
-        manifold_id: ContactManifoldIndex,
-        manifold: &ContactManifold,
-        bodies: &RigidBodySet,
-        out_constraints: &mut Vec<AnyVelocityConstraint>,
-        insert_at: Option<usize>,
-    ) {
-        let cfm_factor = params.cfm_factor();
-        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 (vels1, world_com1) = if let Some(handle1) = handle1 {
-            let rb1 = &bodies[handle1];
-            (rb1.vels, rb1.mprops.world_com)
-        } else {
-            (RigidBodyVelocity::zero(), Point::origin())
-        };
-
-        let rb2 = &bodies[handle2.unwrap()];
-        let vels2 = &rb2.vels;
-        let mprops2 = &rb2.mprops;
-
-        #[cfg(feature = "dim2")]
-        let tangents1 = force_dir1.orthonormal_basis();
-        #[cfg(feature = "dim3")]
-        let tangents1 =
-            super::compute_tangent_contact_directions(&force_dir1, &vels1.linvel, &vels2.linvel);
-
-        let mj_lambda2 = rb2.ids.active_set_offset;
-
-        for (_l, manifold_points) in manifold
-            .data
-            .solver_contacts
-            .chunks(MAX_MANIFOLD_POINTS)
-            .enumerate()
-        {
-            #[cfg(not(target_arch = "wasm32"))]
-            let mut constraint = VelocityGroundConstraint {
-                dir1: force_dir1,
-                #[cfg(feature = "dim3")]
-                tangent1: tangents1[0],
-                elements: [VelocityGroundConstraintElement::zero(); MAX_MANIFOLD_POINTS],
-                im2: mprops2.effective_inv_mass,
-                cfm_factor,
-                limit: 0.0,
-                mj_lambda2,
-                manifold_id,
-                manifold_contact_id: [0; MAX_MANIFOLD_POINTS],
-                num_contacts: manifold_points.len() as u8,
-            };
-
-            // TODO: this is a WIP optimization for WASM platforms.
-            // For some reasons, the compiler does not inline the `Vec::push` method
-            // in this method. This generates two memset and one memcpy which are both very
-            // expansive.
-            // This would likely be solved by some kind of "placement-push" (like emplace in C++).
-            // In the mean time, a workaround is to "push" using `.resize_with` and `::uninit()` to
-            // avoid spurious copying.
-            // Is this optimization beneficial when targeting non-WASM platforms?
-            //
-            // NOTE: impulse_joints have the same problem, but it is not easy to refactor the code that way
-            // for the moment.
-            #[cfg(target_arch = "wasm32")]
-            let constraint = if insert_at.is_none() {
-                let new_len = out_constraints.len() + 1;
-                unsafe {
-                    #[allow(invalid_value)]
-                    out_constraints.resize_with(new_len, || {
-                        AnyVelocityConstraint::NongroupedGround(
-                            std::mem::MaybeUninit::uninit().assume_init(),
-                        )
-                    });
-                }
-                out_constraints
-                    .last_mut()
-                    .unwrap()
-                    .as_nongrouped_ground_mut()
-                    .unwrap()
-            } else {
-                unreachable!(); // We don't have parallelization on WASM yet, so this is unreachable.
-            };
-
-            #[cfg(target_arch = "wasm32")]
-            {
-                constraint.dir1 = force_dir1;
-                #[cfg(feature = "dim3")]
-                {
-                    constraint.tangent1 = tangents1[0];
-                }
-                constraint.im2 = mprops2.effective_inv_mass;
-                constraint.cfm_factor = cfm_factor;
-                constraint.limit = 0.0;
-                constraint.mj_lambda2 = mj_lambda2;
-                constraint.manifold_id = manifold_id;
-                constraint.manifold_contact_id = [0; MAX_MANIFOLD_POINTS];
-                constraint.num_contacts = manifold_points.len() as u8;
-            }
-
-            let mut is_fast_contact = false;
-
-            for k in 0..manifold_points.len() {
-                let manifold_point = &manifold_points[k];
-                let dp2 = manifold_point.point - mprops2.world_com;
-                let dp1 = manifold_point.point - world_com1;
-                let vel1 = vels1.linvel + vels1.angvel.gcross(dp1);
-                let vel2 = vels2.linvel + vels2.angvel.gcross(dp2);
-
-                constraint.limit = manifold_point.friction;
-                constraint.manifold_contact_id[k] = manifold_point.contact_id;
-
-                // Normal part.
-                {
-                    let gcross2 = mprops2
-                        .effective_world_inv_inertia_sqrt
-                        .transform_vector(dp2.gcross(-force_dir1));
-
-                    let projected_mass = utils::inv(
-                        force_dir1.dot(&mprops2.effective_inv_mass.component_mul(&force_dir1))
-                            + gcross2.gdot(gcross2),
-                    );
-
-                    let is_bouncy = manifold_point.is_bouncy() as u32 as Real;
-                    let is_resting = 1.0 - is_bouncy;
-
-                    let dvel = (vel1 - vel2).dot(&force_dir1);
-                    let mut rhs_wo_bias = (1.0 + is_bouncy * manifold_point.restitution) * dvel;
-                    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 + params.allowed_linear_error).clamp(-params.max_penetration_correction, 0.0);
-
-                    let rhs = rhs_wo_bias + rhs_bias;
-                    is_fast_contact =
-                        is_fast_contact || (-rhs * params.dt > rb2.ccd.ccd_thickness * 0.5);
-
-                    constraint.elements[k].normal_part = VelocityGroundConstraintNormalPart {
-                        gcross2,
-                        rhs,
-                        rhs_wo_bias,
-                        impulse: na::zero(),
-                        r: projected_mass,
-                    };
-                }
-
-                // Tangent parts.
-                {
-                    constraint.elements[k].tangent_part.impulse = na::zero();
-
-                    for j in 0..DIM - 1 {
-                        let gcross2 = mprops2
-                            .effective_world_inv_inertia_sqrt
-                            .transform_vector(dp2.gcross(-tangents1[j]));
-                        let r = tangents1[j]
-                            .dot(&mprops2.effective_inv_mass.component_mul(&tangents1[j]))
-                            + gcross2.gdot(gcross2);
-                        let rhs = (vel1 - vel2
-                            + flipped_multiplier * manifold_point.tangent_velocity)
-                            .dot(&tangents1[j]);
-
-                        constraint.elements[k].tangent_part.gcross2[j] = gcross2;
-                        constraint.elements[k].tangent_part.rhs[j] = rhs;
-                        constraint.elements[k].tangent_part.r[j] = if cfg!(feature = "dim2") {
-                            utils::inv(r)
-                        } else {
-                            r
-                        };
-                    }
-
-                    #[cfg(feature = "dim3")]
-                    {
-                        constraint.elements[k].tangent_part.r[2] = 2.0
-                            * constraint.elements[k].tangent_part.gcross2[0]
-                                .gdot(constraint.elements[k].tangent_part.gcross2[1]);
-                    }
-                }
-            }
-
-            constraint.cfm_factor = if is_fast_contact { 1.0 } else { cfm_factor };
-
-            #[cfg(not(target_arch = "wasm32"))]
-            if let Some(at) = insert_at {
-                out_constraints[at + _l] = AnyVelocityConstraint::NongroupedGround(constraint);
-            } else {
-                out_constraints.push(AnyVelocityConstraint::NongroupedGround(constraint));
-            }
-        }
-    }
-
-    pub fn solve(
-        &mut self,
-        mj_lambdas: &mut [DeltaVel<Real>],
-        solve_normal: bool,
-        solve_friction: bool,
-    ) {
-        let mut mj_lambda2 = mj_lambdas[self.mj_lambda2 as usize];
-
-        VelocityGroundConstraintElement::solve_group(
-            self.cfm_factor,
-            &mut self.elements[..self.num_contacts as usize],
-            &self.dir1,
-            #[cfg(feature = "dim3")]
-            &self.tangent1,
-            &self.im2,
-            self.limit,
-            &mut mj_lambda2,
-            solve_normal,
-            solve_friction,
-        );
-
-        mj_lambdas[self.mj_lambda2 as usize] = mj_lambda2;
-    }
-
-    // FIXME: duplicated code. This is exactly the same as in the non-ground velocity constraint.
-    pub fn writeback_impulses(&self, manifolds_all: &mut [&mut ContactManifold]) {
-        let manifold = &mut manifolds_all[self.manifold_id];
-
-        for k in 0..self.num_contacts as usize {
-            let contact_id = self.manifold_contact_id[k];
-            let active_contact = &mut manifold.points[contact_id as usize];
-            active_contact.data.impulse = self.elements[k].normal_part.impulse;
-
-            #[cfg(feature = "dim2")]
-            {
-                active_contact.data.tangent_impulse = self.elements[k].tangent_part.impulse[0];
-            }
-            #[cfg(feature = "dim3")]
-            {
-                active_contact.data.tangent_impulse = self.elements[k].tangent_part.impulse;
-            }
-        }
-    }
-
-    pub fn remove_cfm_and_bias_from_rhs(&mut self) {
-        self.cfm_factor = 1.0;
-        for elt in &mut self.elements {
-            elt.normal_part.rhs = elt.normal_part.rhs_wo_bias;
-        }
-    }
-}