feat: add warmstarting to contact constraints resolution

examples2d/s2d_high_mass_ratio_3.rs

@@ -0,0 +1,49 @@
+use rapier2d::prelude::*;
+use rapier_testbed2d::Testbed;
+
+pub fn init_world(testbed: &mut Testbed) {
+    /*
+     * World
+     */
+    let mut bodies = RigidBodySet::new();
+    let mut colliders = ColliderSet::new();
+    let impulse_joints = ImpulseJointSet::new();
+    let multibody_joints = MultibodyJointSet::new();
+
+    let extent = 1.0;
+    let friction = 0.6;
+
+    /*
+     * Ground
+     */
+    let ground_width = 66.0 * extent;
+
+    let rigid_body = RigidBodyBuilder::fixed().translation(vector![0.0, -2.0]);
+    let ground_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(40.0, 2.0).friction(friction);
+    colliders.insert_with_parent(collider, ground_handle, &mut bodies);
+
+    /*
+     * Create the cubes
+     */
+    let rigid_body = RigidBodyBuilder::dynamic().translation(vector![-9.0 * extent, 0.5 * extent]);
+    let ground_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(0.5 * extent, 0.5 * extent).friction(friction);
+    colliders.insert_with_parent(collider, ground_handle, &mut bodies);
+
+    let rigid_body = RigidBodyBuilder::dynamic().translation(vector![9.0 * extent, 0.5 * extent]);
+    let ground_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(0.5 * extent, 0.5 * extent).friction(friction);
+    colliders.insert_with_parent(collider, ground_handle, &mut bodies);
+
+    let rigid_body = RigidBodyBuilder::dynamic().translation(vector![0.0, (10.0 + 16.0) * extent]);
+    let ground_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(10.0 * extent, 10.0 * extent).friction(friction);
+    colliders.insert_with_parent(collider, ground_handle, &mut bodies);
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.look_at(point![0.0, 2.5], 20.0);
+}