Fix constraints resolution with non-identity relative collider position.

8 files changed, 84 insertions, 45 deletions

diff --git a/src/dynamics/solver/position_constraint.rs b/src/dynamics/solver/position_constraint.rs
index 608a342..69fcf57 100644
--- a/src/dynamics/solver/position_constraint.rs
+++ b/src/dynamics/solver/position_constraint.rs
@@ -104,8 +104,8 @@ impl PositionConstraint {
             let mut local_p2 = [Point::origin(); MAX_MANIFOLD_POINTS];
 
             for l in 0..manifold_points.len() {
-                local_p1[l] = manifold_points[l].local_p1 + shift1;
-                local_p2[l] = manifold_points[l].local_p2 + shift2;
+                local_p1[l] = manifold.delta1 * (manifold_points[l].local_p1 + shift1);
+                local_p2[l] = manifold.delta2 * (manifold_points[l].local_p2 + shift2);
             }
 
             let constraint = PositionConstraint {
diff --git a/src/dynamics/solver/position_constraint_wide.rs b/src/dynamics/solver/position_constraint_wide.rs
index 8828c3d..0633926 100644
--- a/src/dynamics/solver/position_constraint_wide.rs
+++ b/src/dynamics/solver/position_constraint_wide.rs
@@ -51,6 +51,9 @@ impl WPositionConstraint {
         let radius1 = SimdFloat::from(array![|ii| manifolds[ii].kinematics.radius1; SIMD_WIDTH]);
         let radius2 = SimdFloat::from(array![|ii| manifolds[ii].kinematics.radius2; SIMD_WIDTH]);
 
+        let delta1 = Isometry::from(array![|ii| manifolds[ii].delta1; SIMD_WIDTH]);
+        let delta2 = Isometry::from(array![|ii| manifolds[ii].delta2; SIMD_WIDTH]);
+
         let rb1 = array![|ii| rbs1[ii].active_set_offset; SIMD_WIDTH];
         let rb2 = array![|ii| rbs2[ii].active_set_offset; SIMD_WIDTH];
 
@@ -85,8 +88,8 @@ impl WPositionConstraint {
                 let local_p2 =
                     Point::from(array![|ii| manifold_points[ii][i].local_p2; SIMD_WIDTH]);
 
-                constraint.local_p1[i] = local_p1 + shift1;
-                constraint.local_p2[i] = local_p2 + shift2;
+                constraint.local_p1[i] = delta1 * (local_p1 + shift1);
+                constraint.local_p2[i] = delta2 * (local_p2 + shift2);
             }
 
             if push {
diff --git a/src/dynamics/solver/position_ground_constraint.rs b/src/dynamics/solver/position_ground_constraint.rs
index e6e83c6..dcd2d64 100644
--- a/src/dynamics/solver/position_ground_constraint.rs
+++ b/src/dynamics/solver/position_ground_constraint.rs
@@ -34,22 +34,30 @@ impl PositionGroundConstraint {
 
         let local_n1;
         let local_n2;
+        let delta1;
+        let delta2;
 
         if flip {
             std::mem::swap(&mut rb1, &mut rb2);
             local_n1 = manifold.local_n2;
             local_n2 = manifold.local_n1;
+            delta1 = &manifold.delta2;
+            delta2 = &manifold.delta1;
         } else {
             local_n1 = manifold.local_n1;
             local_n2 = manifold.local_n2;
+            delta1 = &manifold.delta1;
+            delta2 = &manifold.delta2;
         };
 
+        let coll_pos1 = rb1.position * delta1;
         let shift1 = local_n1 * -manifold.kinematics.radius1;
         let shift2 = local_n2 * -manifold.kinematics.radius2;
+        let n1 = coll_pos1 * local_n1;
         let radius =
             manifold.kinematics.radius1 + manifold.kinematics.radius2 /* - params.allowed_linear_error */;
 
-        for (l, manifold_points) in manifold
+        for (l, manifold_contacts) in manifold
             .active_contacts()
             .chunks(MAX_MANIFOLD_POINTS)
             .enumerate()
@@ -59,16 +67,16 @@ impl PositionGroundConstraint {
 
             if flip {
                 // Don't forget that we already swapped rb1 and rb2 above.
-                // So if we flip, only manifold_points[k].{local_p1,local_p2} have to
+                // So if we flip, only manifold_contacts[k].{local_p1,local_p2} have to
                 // be swapped.
-                for k in 0..manifold_points.len() {
-                    p1[k] = rb1.predicted_position * (manifold_points[k].local_p2 + shift1);
-                    local_p2[k] = manifold_points[k].local_p1 + shift2;
+                for k in 0..manifold_contacts.len() {
+                    p1[k] = coll_pos1 * (manifold_contacts[k].local_p2 + shift1);
+                    local_p2[k] = delta2 * (manifold_contacts[k].local_p1 + shift2);
                 }
             } else {
-                for k in 0..manifold_points.len() {
-                    p1[k] = rb1.predicted_position * (manifold_points[k].local_p1 + shift1);
-                    local_p2[k] = manifold_points[k].local_p2 + shift2;
+                for k in 0..manifold_contacts.len() {
+                    p1[k] = coll_pos1 * (manifold_contacts[k].local_p1 + shift1);
+                    local_p2[k] = delta2 * (manifold_contacts[k].local_p2 + shift2);
                 }
             }
 
@@ -76,11 +84,11 @@ impl PositionGroundConstraint {
                 rb2: rb2.active_set_offset,
                 p1,
                 local_p2,
-                n1: rb1.predicted_position * local_n1,
+                n1,
                 radius,
                 im2: rb2.mass_properties.inv_mass,
                 ii2: rb2.world_inv_inertia_sqrt.squared(),
-                num_contacts: manifold_points.len() as u8,
+                num_contacts: manifold_contacts.len() as u8,
                 erp: params.erp,
                 max_linear_correction: params.max_linear_correction,
             };
diff --git a/src/dynamics/solver/position_ground_constraint_wide.rs b/src/dynamics/solver/position_ground_constraint_wide.rs
index faa928b..e423c0a 100644
--- a/src/dynamics/solver/position_ground_constraint_wide.rs
+++ b/src/dynamics/solver/position_ground_constraint_wide.rs
@@ -54,16 +54,24 @@ impl WPositionGroundConstraint {
             array![|ii| if flipped[ii] { manifolds[ii].local_n1 } else { manifolds[ii].local_n2 }; SIMD_WIDTH],
         );
 
+        let delta1 = Isometry::from(
+            array![|ii| if flipped[ii] { manifolds[ii].delta2 } else { manifolds[ii].delta1 }; SIMD_WIDTH],
+        );
+        let delta2 = Isometry::from(
+            array![|ii| if flipped[ii] { manifolds[ii].delta1 } else { manifolds[ii].delta2 }; SIMD_WIDTH],
+        );
+
         let radius1 = SimdFloat::from(array![|ii| manifolds[ii].kinematics.radius1; SIMD_WIDTH]);
         let radius2 = SimdFloat::from(array![|ii| manifolds[ii].kinematics.radius2; SIMD_WIDTH]);
 
-        let position1 = Isometry::from(array![|ii| rbs1[ii].predicted_position; SIMD_WIDTH]);
+        let coll_pos1 =
+            delta1 * Isometry::from(array![|ii| rbs1[ii].predicted_position; SIMD_WIDTH]);
 
         let rb2 = array![|ii| rbs2[ii].active_set_offset; SIMD_WIDTH];
 
         let radius = radius1 + radius2 /*- SimdFloat::splat(params.allowed_linear_error)*/;
 
-        let n1 = position1 * local_n1;
+        let n1 = coll_pos1 * local_n1;
 
         for l in (0..manifolds[0].num_active_contacts()).step_by(MAX_MANIFOLD_POINTS) {
             let manifold_points = array![|ii| &manifolds[ii].active_contacts()[l..]; SIMD_WIDTH];
@@ -90,8 +98,8 @@ impl WPositionGroundConstraint {
                     array![|ii| if flipped[ii] { manifold_points[ii][i].local_p1 } else { manifold_points[ii][i].local_p2 }; SIMD_WIDTH],
                 );
 
-                constraint.p1[i] = position1 * local_p1 - n1 * radius1;
-                constraint.local_p2[i] = local_p2 - local_n2 * radius2;
+                constraint.p1[i] = coll_pos1 * local_p1 - n1 * radius1;
+                constraint.local_p2[i] = delta2 * (local_p2 - local_n2 * radius2);
             }
 
             if push {
diff --git a/src/dynamics/solver/velocity_constraint.rs b/src/dynamics/solver/velocity_constraint.rs
index eb80018..190076d 100644
--- a/src/dynamics/solver/velocity_constraint.rs
+++ b/src/dynamics/solver/velocity_constraint.rs
@@ -148,7 +148,9 @@ impl VelocityConstraint {
         let rb2 = &bodies[manifold.body_pair.body2];
         let mj_lambda1 = rb1.active_set_offset;
         let mj_lambda2 = rb2.active_set_offset;
-        let force_dir1 = rb1.position * (-manifold.local_n1);
+        let pos_coll1 = rb1.position * manifold.delta1;
+        let pos_coll2 = rb2.position * manifold.delta2;
+        let force_dir1 = pos_coll1 * (-manifold.local_n1);
         let warmstart_coeff = manifold.warmstart_multiplier * params.warmstart_coeff;
 
         for (l, manifold_points) in manifold
@@ -215,8 +217,8 @@ impl VelocityConstraint {
 
             for k in 0..manifold_points.len() {
                 let manifold_point = &manifold_points[k];
-                let dp1 = (rb1.position * manifold_point.local_p1) - rb1.world_com;
-                let dp2 = (rb2.position * manifold_point.local_p2) - rb2.world_com;
+                let dp1 = (pos_coll1 * manifold_point.local_p1) - rb1.world_com;
+                let dp2 = (pos_coll2 * manifold_point.local_p2) - rb2.world_com;
 
                 let vel1 = rb1.linvel + rb1.angvel.gcross(dp1);
                 let vel2 = rb2.linvel + rb2.angvel.gcross(dp2);
diff --git a/src/dynamics/solver/velocity_constraint_wide.rs b/src/dynamics/solver/velocity_constraint_wide.rs
index 4204e68..f515d5e 100644
--- a/src/dynamics/solver/velocity_constraint_wide.rs
+++ b/src/dynamics/solver/velocity_constraint_wide.rs
@@ -72,6 +72,9 @@ impl WVelocityConstraint {
         let rbs1 = array![|ii| &bodies[manifolds[ii].body_pair.body1]; SIMD_WIDTH];
         let rbs2 = array![|ii| &bodies[manifolds[ii].body_pair.body2]; SIMD_WIDTH];
 
+        let delta1 = Isometry::from(array![|ii| manifolds[ii].delta1; SIMD_WIDTH]);
+        let delta2 = Isometry::from(array![|ii| manifolds[ii].delta2; SIMD_WIDTH]);
+
         let im1 = SimdFloat::from(array![|ii| rbs1[ii].mass_properties.inv_mass; SIMD_WIDTH]);
         let ii1: AngularInertia<SimdFloat> =
             AngularInertia::from(array![|ii| rbs1[ii].world_inv_inertia_sqrt; SIMD_WIDTH]);
@@ -79,7 +82,7 @@ impl WVelocityConstraint {
         let linvel1 = Vector::from(array![|ii| rbs1[ii].linvel; SIMD_WIDTH]);
         let angvel1 = AngVector::<SimdFloat>::from(array![|ii| rbs1[ii].angvel; SIMD_WIDTH]);
 
-        let position1 = Isometry::from(array![|ii| rbs1[ii].position; SIMD_WIDTH]);
+        let pos1 = Isometry::from(array![|ii| rbs1[ii].position; SIMD_WIDTH]);
         let world_com1 = Point::from(array![|ii| rbs1[ii].world_com; SIMD_WIDTH]);
 
         let im2 = SimdFloat::from(array![|ii| rbs2[ii].mass_properties.inv_mass; SIMD_WIDTH]);
@@ -89,10 +92,13 @@ impl WVelocityConstraint {
         let linvel2 = Vector::from(array![|ii| rbs2[ii].linvel; SIMD_WIDTH]);
         let angvel2 = AngVector::<SimdFloat>::from(array![|ii| rbs2[ii].angvel; SIMD_WIDTH]);
 
-        let position2 = Isometry::from(array![|ii| rbs2[ii].position; SIMD_WIDTH]);
+        let pos2 = Isometry::from(array![|ii| rbs2[ii].position; SIMD_WIDTH]);
         let world_com2 = Point::from(array![|ii| rbs2[ii].world_com; SIMD_WIDTH]);
 
-        let force_dir1 = position1 * -Vector::from(array![|ii| manifolds[ii].local_n1; SIMD_WIDTH]);
+        let coll_pos1 = pos1 * delta1;
+        let coll_pos2 = pos2 * delta2;
+
+        let force_dir1 = coll_pos1 * -Vector::from(array![|ii| manifolds[ii].local_n1; SIMD_WIDTH]);
 
         let mj_lambda1 = array![|ii| rbs1[ii].active_set_offset; SIMD_WIDTH];
         let mj_lambda2 = array![|ii| rbs2[ii].active_set_offset; SIMD_WIDTH];
@@ -120,11 +126,11 @@ impl WVelocityConstraint {
             };
 
             for k in 0..num_points {
-                // FIXME: can we avoid the multiplications by position1/position2 here?
+                // FIXME: can we avoid the multiplications by coll_pos1/coll_pos2 here?
                 // By working as much as possible in local-space.
-                let p1 = position1
+                let p1 = coll_pos1
                     * Point::from(array![|ii| manifold_points[ii][k].local_p1; SIMD_WIDTH]);
-                let p2 = position2
+                let p2 = coll_pos2
                     * Point::from(array![|ii| manifold_points[ii][k].local_p2; SIMD_WIDTH]);
 
                 let dist = SimdFloat::from(array![|ii| manifold_points[ii][k].dist; SIMD_WIDTH]);
diff --git a/src/dynamics/solver/velocity_ground_constraint.rs b/src/dynamics/solver/velocity_ground_constraint.rs
index 65a61bd..d9229ff 100644
--- a/src/dynamics/solver/velocity_ground_constraint.rs
+++ b/src/dynamics/solver/velocity_ground_constraint.rs
@@ -66,20 +66,22 @@ impl VelocityGroundConstraint {
         let mut rb1 = &bodies[manifold.body_pair.body1];
         let mut rb2 = &bodies[manifold.body_pair.body2];
         let flipped = !rb2.is_dynamic();
+        let force_dir1;
+        let coll_pos1;
+        let coll_pos2;
 
         if flipped {
+            coll_pos1 = rb2.position * manifold.delta2;
+            coll_pos2 = rb1.position * manifold.delta1;
+            force_dir1 = coll_pos1 * (-manifold.local_n2);
             std::mem::swap(&mut rb1, &mut rb2);
+        } else {
+            coll_pos1 = rb1.position * manifold.delta1;
+            coll_pos2 = rb2.position * manifold.delta2;
+            force_dir1 = coll_pos1 * (-manifold.local_n1);
         }
 
         let mj_lambda2 = rb2.active_set_offset;
-        let force_dir1 = if flipped {
-            // NOTE: we already swapped rb1 and rb2
-            // so we multiply by rb1.position.
-            rb1.position * (-manifold.local_n2)
-        } else {
-            rb1.position * (-manifold.local_n1)
-        };
-
         let warmstart_coeff = manifold.warmstart_multiplier * params.warmstart_coeff;
 
         for (l, manifold_points) in manifold
@@ -144,15 +146,15 @@ impl VelocityGroundConstraint {
                 let manifold_point = &manifold_points[k];
                 let (p1, p2) = if flipped {
                     // NOTE: we already swapped rb1 and rb2
-                    // so we multiply by rb2.position.
+                    // so we multiply by coll_pos1/coll_pos2.
                     (
-                        rb1.position * manifold_point.local_p2,
-                        rb2.position * manifold_point.local_p1,
+                        coll_pos1 * manifold_point.local_p2,
+                        coll_pos2 * manifold_point.local_p1,
                     )
                 } else {
                     (
-                        rb1.position * manifold_point.local_p1,
-                        rb2.position * manifold_point.local_p2,
+                        coll_pos1 * manifold_point.local_p1,
+                        coll_pos2 * manifold_point.local_p2,
                     )
                 };
                 let dp2 = p2 - rb2.world_com;
diff --git a/src/dynamics/solver/velocity_ground_constraint_wide.rs b/src/dynamics/solver/velocity_ground_constraint_wide.rs
index af2e1e9..18e9257 100644
--- a/src/dynamics/solver/velocity_ground_constraint_wide.rs
+++ b/src/dynamics/solver/velocity_ground_constraint_wide.rs
@@ -86,13 +86,23 @@ impl WVelocityGroundConstraint {
         let linvel2 = Vector::from(array![|ii| rbs2[ii].linvel; SIMD_WIDTH]);
         let angvel2 = AngVector::<SimdFloat>::from(array![|ii| rbs2[ii].angvel; SIMD_WIDTH]);
 
-        let position1 = Isometry::from(array![|ii| rbs1[ii].position; SIMD_WIDTH]);
-        let position2 = Isometry::from(array![|ii| rbs2[ii].position; SIMD_WIDTH]);
+        let pos1 = Isometry::from(array![|ii| rbs1[ii].position; SIMD_WIDTH]);
+        let pos2 = Isometry::from(array![|ii| rbs2[ii].position; SIMD_WIDTH]);
+
+        let delta1 = Isometry::from(
+            array![|ii| if flipped[ii] { manifolds[ii].delta2 } else { manifolds[ii].delta1 }; SIMD_WIDTH],
+        );
+        let delta2 = Isometry::from(
+            array![|ii| if flipped[ii] { manifolds[ii].delta1 } else { manifolds[ii].delta2 }; SIMD_WIDTH],
+        );
+
+        let coll_pos1 = pos1 * delta1;
+        let coll_pos2 = pos2 * delta2;
 
         let world_com1 = Point::from(array![|ii| rbs1[ii].world_com; SIMD_WIDTH]);
         let world_com2 = Point::from(array![|ii| rbs2[ii].world_com; SIMD_WIDTH]);
 
-        let force_dir1 = position1
+        let force_dir1 = coll_pos1
             * -Vector::from(
                 array![|ii| if flipped[ii] { manifolds[ii].local_n2 } else { manifolds[ii].local_n1 }; SIMD_WIDTH],
             );
@@ -120,11 +130,11 @@ impl WVelocityGroundConstraint {
             };
 
             for k in 0..num_points {
-                let p1 = position1
+                let p1 = coll_pos1
                     * Point::from(
                         array![|ii| if flipped[ii] { manifold_points[ii][k].local_p2 } else { manifold_points[ii][k].local_p1 }; SIMD_WIDTH],
                     );
-                let p2 = position2
+                let p2 = coll_pos2
                     * Point::from(
                         array![|ii| if flipped[ii] { manifold_points[ii][k].local_p1 } else { manifold_points[ii][k].local_p2 }; SIMD_WIDTH],
                     );