Collisions

Collisions are currently handled with object-level collision events. These events pass 4 parameters: the other object being collided with, the difference in velocity between the two objects (essentially the speed of impact),the difference in angular velocity, and the contact normal between this and other_object.

var mesh = new Physijs.SphereMesh(
    new THREE.SphereGeometry( 3 ),
    new THREE.MeshBasicMaterial({ color: 0x888888 })
);
mesh.addEventListener( 'collision', function( other_object, relative_velocity, relative_rotation, contact_normal ) {
    // `this` has collided with `other_object` with an impact speed of `relative_velocity` and a rotational force of `relative_rotation` and at normal `contact_normal`
});

See the collisions example for details on implementing and using this event.

Motion Clamping

When an object has a high velocity, collisions can be missed if it moves through and past other objects between simulation steps. To fix this, enable CCD motion clamping. For a cube of size 1 try:

// Enable CCD if the object moves more than 1 meter in one simulation frame
mesh.setCcdMotionThreshold(1);

// Set the radius of the embedded sphere such that it is smaller than the object
mesh.setCcdSweptSphereRadius(0.2);

See the Bullet wiki page on motion clamping for more information.

Future Plans

In the future a global collision report will be sent to the scene's update event.