feat: add warmstarting to contact constraints resolution

examples2d/s2d_card_house.rs

@@ -0,0 +1,79 @@
+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 = 0.7;
+
+    /*
+     * Ground
+     */
+    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 scale = 10.0;
+    let card_height = 0.2 * scale;
+    let card_thickness = 0.001 * scale;
+    let angle0 = 25.0 * std::f32::consts::PI / 180.0;
+    let angle1 = -25.0 * std::f32::consts::PI / 180.0;
+    let angle2 = 0.5 * std::f32::consts::PI;
+
+    let card_box = ColliderBuilder::cuboid(card_thickness, card_height).friction(friction);
+
+    let mut nb = 5;
+    let mut z0 = 0.0;
+    let mut y = card_height - 0.02 * scale;
+
+    while nb != 0 {
+        let mut z = z0;
+
+        for i in 0..nb {
+            if i != nb - 1 {
+                let rigid_body = RigidBodyBuilder::dynamic()
+                    .translation(vector![z + 0.25 * scale, y + card_height - 0.015 * scale])
+                    .rotation(angle2);
+                let ground_handle = bodies.insert(rigid_body);
+                colliders.insert_with_parent(card_box.clone(), ground_handle, &mut bodies);
+            }
+
+            let rigid_body = RigidBodyBuilder::dynamic()
+                .translation(vector![z, y])
+                .rotation(angle1);
+            let ground_handle = bodies.insert(rigid_body);
+            colliders.insert_with_parent(card_box.clone(), ground_handle, &mut bodies);
+
+            z += 0.175 * scale;
+
+            let rigid_body = RigidBodyBuilder::dynamic()
+                .translation(vector![z, y])
+                .rotation(angle0);
+            let ground_handle = bodies.insert(rigid_body);
+            colliders.insert_with_parent(card_box.clone(), ground_handle, &mut bodies);
+
+            z += 0.175 * scale;
+        }
+
+        y += card_height * 2.0 - 0.03 * scale;
+        z0 += 0.175 * scale;
+        nb -= 1;
+    }
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.look_at(point![0.0, 2.5], 20.0);
+}