Add damping support + demos.

examples2d/all_examples2.rs

@@ -12,6 +12,7 @@ use std::cmp::Ordering;
 
 mod add_remove2;
 mod collision_groups2;
+mod damping2;
 mod debug_box_ball2;
 mod heightfield2;
 mod joints2;
@@ -55,6 +56,7 @@ pub fn main() {
     let mut builders: Vec<(_, fn(&mut Testbed))> = vec![
         ("Add remove", add_remove2::init_world),
         ("Collision groups", collision_groups2::init_world),
+        ("Damping", damping2::init_world),
         ("Heightfield", heightfield2::init_world),
         ("Joints", joints2::init_world),
         ("Platform", platform2::init_world),

examples2d/damping2.rs

@@ -0,0 +1,45 @@
+use na::{Point2, Vector2};
+use rapier2d::dynamics::{JointSet, RigidBodyBuilder, RigidBodySet};
+use rapier2d::geometry::{ColliderBuilder, ColliderSet};
+use rapier_testbed2d::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)
+            .linvel(x * 10.0, y * 10.0)
+            .angvel(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).build();
+        colliders.insert(co, rb_handle, &mut bodies);
+    }
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world_with_gravity(bodies, colliders, joints, Vector2::zeros());
+    testbed.look_at(Point2::new(3.0, 2.0), 50.0);
+}