1 files changed, 75 insertions, 0 deletions
diff --git a/examples2d/joints2.rs b/examples2d/joints2.rs
new file mode 100644
index 0000000..c3df921
--- /dev/null
+++ b/examples2d/joints2.rs
@@ -0,0 +1,75 @@
+use na::Point2;
+use rapier2d::dynamics::{BallJoint, BodyStatus, 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 mut joints = JointSet::new();
+
+    /*
+     * Create the balls
+     */
+    // Build the rigid body.
+    // NOTE: a smaller radius (e.g. 0.1) breaks Box2D so
+    // in order to be able to compare rapier with Box2D,
+    // we set it to 0.4.
+    let rad = 0.4;
+    let numi = 100; // Num vertical nodes.
+    let numk = 100; // Num horizontal nodes.
+    let shift = 1.0;
+
+    let mut body_handles = Vec::new();
+
+    for k in 0..numk {
+        for i in 0..numi {
+            let fk = k as f32;
+            let fi = i as f32;
+
+            let status = if i == 0 && (k % 4 == 0 || k == numk - 1) {
+                BodyStatus::Static
+            } else {
+                BodyStatus::Dynamic
+            };
+
+            let rigid_body = RigidBodyBuilder::new(status)
+                .translation(fk * shift, -fi * shift)
+                .build();
+            let child_handle = bodies.insert(rigid_body);
+            let collider = ColliderBuilder::ball(rad).density(1.0).build();
+            colliders.insert(collider, child_handle, &mut bodies);
+
+            // Vertical joint.
+            if i > 0 {
+                let parent_handle = *body_handles.last().unwrap();
+                let joint = BallJoint::new(Point2::origin(), Point2::new(0.0, shift));
+                joints.insert(&mut bodies, parent_handle, child_handle, joint);
+            }
+
+            // Horizontal joint.
+            if k > 0 {
+                let parent_index = body_handles.len() - numi;
+                let parent_handle = body_handles[parent_index];
+                let joint = BallJoint::new(Point2::origin(), Point2::new(-shift, 0.0));
+                joints.insert(&mut bodies, parent_handle, child_handle, joint);
+            }
+
+            body_handles.push(child_handle);
+        }
+    }
+
+    /*
+     * Set up the testbed.
+     */
+    testbed.set_world(bodies, colliders, joints);
+    testbed.look_at(Point2::new(numk as f32 * rad, numi as f32 * -rad), 5.0);
+}
+
+fn main() {
+    let testbed = Testbed::from_builders(0, vec![("Joints", init_world)]);
+    testbed.run()
+}