use rapier_testbed3d::TestbedViewer;
use rapier3d::prelude::*;

// This shows a bug when a cylinder is in contact with a very large
// but very thin cuboid. In this case the EPA returns an incorrect
// contact normal, resulting in the cylinder falling through the floor.
pub async fn run(viewer: &mut TestbedViewer) -> anyhow::Result<()> {
    /*
     * World
     */
    let mut world = PhysicsWorld::new();

    /*
     * Ground
     */
    let ground_size = 100.1;
    let ground_height = 0.1;

    let rigid_body = RigidBodyBuilder::fixed().translation(Vector::new(0.0, -ground_height, 0.0));
    let collider = ColliderBuilder::cuboid(ground_size, ground_height, ground_size);
    let (_handle, _) = world.insert(rigid_body, collider);

    /*
     * Create the cubes
     */
    let num = 1;
    let rad = 1.0;

    let shiftx = rad * 2.0 + rad;
    let shifty = rad * 2.0 + rad;
    let shiftz = rad * 2.0 + rad;
    let centerx = shiftx * (num / 2) as f32;
    let centery = shifty / 2.0;
    let centerz = shiftz * (num / 2) as f32;

    let offset = -(num as f32) * (rad * 2.0 + rad) * 0.5;

    let x = -centerx + offset;
    let y = centery + 3.0;
    let z = -centerz + offset;

    // Build the rigid body.
    let rigid_body = RigidBodyBuilder::dynamic().translation(Vector::new(x, y, z));
    let collider = ColliderBuilder::cylinder(rad, rad);
    let (_handle, _) = world.insert(rigid_body, collider);

    /*
     * Set up the testbed.
     */
    viewer.set_world(&mut world);
    viewer.look_at(Vec3::new(100.0, 100.0, 100.0), Vec3::ZERO);

    while viewer.render_frame(&mut world).await {
        if viewer.simulating() {
            world.step();
        }
    }
    Ok(())
}
