adding 3d rope joint

examples3d/rope_joints3.rs

@@ -0,0 +1,76 @@
+use rapier3d::prelude::*;
+use rapier_testbed3d::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_size = 0.75;
+    let ground_height = 0.1;
+
+    let rigid_body = RigidBodyBuilder::fixed().translation(vector![0.0, -ground_height, 0.0]);
+    let floor_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(ground_size, ground_height, ground_size);
+    colliders.insert_with_parent(collider, floor_handle, &mut bodies);
+
+
+    let rigid_body = RigidBodyBuilder::fixed().translation(vector![-ground_size - ground_height, ground_height, 0.0]);
+    let floor_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(ground_height, ground_height, ground_size);
+    colliders.insert_with_parent(collider, floor_handle, &mut bodies);
+
+    let rigid_body = RigidBodyBuilder::fixed().translation(vector![ground_size + ground_height, ground_height, 0.0]);
+    let floor_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(ground_height, ground_height, ground_size);
+    colliders.insert_with_parent(collider, floor_handle, &mut bodies);
+
+
+    let rigid_body = RigidBodyBuilder::fixed().translation(vector![0.0, ground_height, -ground_size - ground_height]);
+    let floor_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(ground_size, ground_height, ground_height);
+    colliders.insert_with_parent(collider, floor_handle, &mut bodies);
+
+    let rigid_body = RigidBodyBuilder::fixed().translation(vector![0.0, ground_height, ground_size + ground_height]);
+    let floor_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(ground_size, ground_height, ground_height);
+    colliders.insert_with_parent(collider, floor_handle, &mut bodies);
+
+    /*
+     * Character we will control manually.
+     */
+
+    let rigid_body = RigidBodyBuilder::kinematic_position_based().translation(vector![0.0, 0.3, 0.0]);
+    let character_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::cuboid(0.15, 0.3, 0.15);
+    colliders.insert_with_parent(collider, character_handle, &mut bodies);
+    
+    testbed.set_initial_body_color(character_handle, [255. / 255., 131. / 255., 244.0 / 255.]);
+
+    /*
+     * Tethered Ball
+     */
+    let rad = 0.04;
+
+    let rigid_body = RigidBodyBuilder::new(RigidBodyType::Dynamic).translation(vector![1.0, 1.0, 0.0]);
+    let child_handle = bodies.insert(rigid_body);
+    let collider = ColliderBuilder::ball(rad);
+    colliders.insert_with_parent(collider, child_handle, &mut bodies);
+
+    let joint = RopeJointBuilder::new().local_anchor2(point![0.0, 0.0, 0.0]).limits([2.0, 2.0]);
+    impulse_joints.insert(character_handle, child_handle, joint, true);
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
+    testbed.set_character_body(character_handle);
+    testbed.look_at(point![10.0, 10.0, 10.0], point![0.0, 0.0, 0.0]);
+}