feat: add a few more debug demos

examples2d/debug_total_overlap2.rs

@@ -0,0 +1,28 @@
+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();
+
+    // Build many balls, all spawned at the same point.
+    let rad = 0.5;
+
+    for _ in 0..100 {
+        let rigid_body = RigidBodyBuilder::dynamic();
+        let handle = bodies.insert(rigid_body);
+        let collider = ColliderBuilder::cuboid(rad, rad);
+        colliders.insert_with_parent(collider, handle, &mut bodies);
+    }
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.look_at(point![0.0, 0.0], 50.0);
+}