intersectBoundingSphere method

Vector3? intersectBoundingSphere(BoundingSphere sphere, Vector3 result)

Performs a ray/sphere intersection test and stores the intersection point to the given 3D vector. If no intersection is detected, null is returned.

Implementation

Vector3? intersectBoundingSphere(BoundingSphere sphere, Vector3 result ) {
	v1.subVectors( sphere.center, origin );
	final tca = v1.dot( direction );
	final d2 = v1.dot( v1 ) - tca * tca;
	final radius2 = sphere.radius * sphere.radius;

	if ( d2 > radius2 ) return null;

	final thc = math.sqrt( radius2 - d2 );

	// t0 = first intersect point - entrance on front of sphere
	final t0 = tca - thc;

	// t1 = second intersect point - exit point on back of sphere
	final t1 = tca + thc;

	// test to see if both t0 and t1 are behind the ray - if so, return null
	if ( t0 < 0 && t1 < 0 ) return null;

	// test to see if t0 is behind the ray:
	// if it is, the ray is inside the sphere, so return the second exit point scaled by t1,
	// in order to always return an intersect point that is in front of the ray.
	if ( t0 < 0 ) return at( t1, result );

	// else t0 is in front of the ray, so return the first collision point scaled by t0
	return at( t0, result );
}