scene_queries_shape_casting

Shape-casting (aka. sweep tests) is the big brother of ray-casting. The only difference with ray-cast is that instead of being a point travelling along a straight line, we have a complete shape travelling along a straight line. This is typically used for character controllers in games to determine by how much the player can move before it hits the environment.

info

Just like ray-casting, it is possible to control the behavior of the shape-casting like limiting the distance travelled by the shape cast, and ignoring some colliders. See the details about the max_toi and filter arguments in the ray-casting section.

There is only one shape-casting method: World.castShape. This method has similar arguments as World.castRay except that the ray is replaced by three arguments: the shape being cast, the initial position of the shape (this is analog to ray.origin) and the linear velocity the shape is travelling at (this is analog to ray.dir):

Example 2D

let shapePos = { x: 0.0, y: 1.0 };
let shapeRot = 0.2;
let shapeVel = { x: 0.1, y: 0.4 };
let shape = new RAPIER.Cuboid(1.0, 2.0);
let targetDistance = 0.0;
let maxToi = 4.0;
// Optional parameters:
let stopAtPenetration = true;
let filterFlags = QueryFilterFlags.EXCLUDE_DYNAMIC;
let filterGroups = 0x000b0001;
let filterExcludeCollider = collider;
let filterExcludeRigidBody = rigidBody;

let hit = world.castShape(shapePos, shapeRot, shapeVel, shape, targetDistance, maxToi,
    stopAtPenetration, filterFlags, filterGroups, filterExcludeCollider, filterExcludeRigidBody);
if (hit != null) {
    // The first collider hit has the handle `handle`. The `hit` is a
    // structure containing details about the hit configuration.
    console.log("Hit the collider", hit.collider, "at time", hit.time_of_impact);
}

Example 3D

let shapePos = { x: 0.0, y: 1.0, z: 0.0 };
let shapeRot = { w: 1.0, x: 0.0, y: 0.0, z: 0.0 };
let shapeVel = { x: 0.1, y: 0.4, z: 1.0 };
let shape = new RAPIER.Cuboid(1.0, 2.0, 3.0);
let targetDistance = 0.0;
let maxToi = 4.0;
// Optional parameters:
let stopAtPenetration = true;
let filterFlags = QueryFilterFlags.EXCLUDE_DYNAMIC;
let filterGroups = 0x000b0001;
let filterExcludeCollider = collider;
let filterExcludeRigidBody = rigidBody;

let hit = world.castShape(shapePos, shapeRot, shapeVel, shape, targetDistance, maxToi,
    stopAtPenetration, filterFlags, filterGroups, filterExcludeCollider, filterExcludeRigidBody);
if (hit != null) {
    // The first collider hit has the handle `handle`. The `hit` is a
    // structure containing details about the hit configuration.
    console.log("Hit the collider", hit.collider, "at time", hit.time_of_impact);
}

The result of the shape-casting includes the handle of the first collider being hit, as well as detailed information about the geometry of the hit:

• hit.toi: indicates the time of impact between the shape and the collider hit. This means that after travelling a distance of shapeVel * hit.toi the collider and the cast shape are exactly touching. If hit.toi == 0.0 then the shape is already intersecting a collider at its initial position.
• hit.witness1: indicates the contact point when the cast shape and the collider are touching, expressed in the local-space of the collider hit by the shape.
• hit.witness2: indicates the contact point when the cast shape and the collider are touching, expressed in the local-space of the cast shape.
• hit.normal1: indicates the normal at the contact point hit.witness1, expressed in the local-space of the collider hit by the shape.
• hit.normal2: indicates the normal at the contact point hit.witness2, expressed in the local-space of the cast shape.