Add damping support + demos.

examples3d/damping3.rs

@@ -0,0 +1,45 @@
+use na::{Point3, Vector3};
+use rapier3d::dynamics::{JointSet, RigidBodyBuilder, RigidBodySet};
+use rapier3d::geometry::{ColliderBuilder, ColliderSet};
+use rapier_testbed3d::Testbed;
+
+pub fn init_world(testbed: &mut Testbed) {
+    /*
+     * World
+     */
+    let mut bodies = RigidBodySet::new();
+    let mut colliders = ColliderSet::new();
+    let joints = JointSet::new();
+
+    /*
+     * Create the balls
+     */
+    let num = 10;
+    let rad = 0.2;
+
+    let subdiv = 1.0 / (num as f32);
+
+    for i in 0usize..num {
+        let (x, y) = (i as f32 * subdiv * std::f32::consts::PI * 2.0).sin_cos();
+
+        // Build the rigid body.
+        let rb = RigidBodyBuilder::new_dynamic()
+            .translation(x, y, 0.0)
+            .linvel(x * 10.0, y * 10.0, 0.0)
+            .angvel(Vector3::z() * 100.0)
+            .linear_damping((i + 1) as f32 * subdiv * 10.0)
+            .angular_damping((num - i) as f32 * subdiv * 10.0)
+            .build();
+        let rb_handle = bodies.insert(rb);
+
+        // Build the collider.
+        let co = ColliderBuilder::cuboid(rad, rad, rad).build();
+        colliders.insert(co, rb_handle, &mut bodies);
+    }
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world_with_gravity(bodies, colliders, joints, Vector3::zeros());
+    testbed.look_at(Point3::new(2.0, 2.5, 20.0), Point3::new(2.0, 2.5, 0.0));
+}