copy method
Implementation
void copy(Sphere sphere) {
radius = sphere.radius;
friction = sphere.friction;
restitution = sphere.restitution;
density = sphere.density;
collidesWith = sphere.collidesWith;
belongsTo = sphere.belongsTo;
relativePosition = sphere.relativePosition.clone();
relativeRotation = sphere.relativeRotation.clone();
position = sphere.position.clone();
rotation = sphere.rotation.clone();
}