feat: add warmstarting to contact constraints resolution

examples2d/s2d_bridge.rs

@@ -0,0 +1,56 @@
+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 mut impulse_joints = ImpulseJointSet::new();
+    let multibody_joints = MultibodyJointSet::new();
+
+    /*
+     * Ground
+     */
+    let ground = bodies.insert(RigidBodyBuilder::fixed());
+
+    /*
+     * Create the bridge.
+     */
+    let density = 20.0;
+    let x_base = -80.0;
+    let count = 160;
+    let mut prev = ground;
+
+    for i in 0..count {
+        let rigid_body = RigidBodyBuilder::dynamic()
+            .linear_damping(0.1)
+            .angular_damping(0.1)
+            .translation(vector![x_base + 0.5 + 1.0 * i as f32, 20.0]);
+        let handle = bodies.insert(rigid_body);
+        let collider = ColliderBuilder::cuboid(0.5, 0.125).density(20.0);
+        colliders.insert_with_parent(collider, handle, &mut bodies);
+
+        let pivot = point![x_base + 1.0 * i as f32, 20.0];
+        let joint = RevoluteJointBuilder::new()
+            .local_anchor1(bodies[prev].position().inverse_transform_point(&pivot))
+            .local_anchor2(bodies[handle].position().inverse_transform_point(&pivot))
+            .contacts_enabled(false);
+        impulse_joints.insert(prev, handle, joint, true);
+        prev = handle;
+    }
+
+    let pivot = point![x_base + 1.0 * count as f32, 20.0];
+    let joint = RevoluteJointBuilder::new()
+        .local_anchor1(bodies[prev].position().inverse_transform_point(&pivot))
+        .local_anchor2(bodies[ground].position().inverse_transform_point(&pivot))
+        .contacts_enabled(false);
+    impulse_joints.insert(prev, ground, joint, true);
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.look_at(point![0.0, 2.5], 20.0);
+}