public boolean intersect(Ray ray) {
        float dx = center.x - ray.origin.x;
        float dy = center.y - ray.origin.y;
        float dz = center.z - ray.origin.z;
        float v = ray.direction.dot(dx, dy, dz);

        // Do the following quick check to see if there is even a chance
        // that an intersection here might be closer than a previous one
        if (v - radius > ray.t) return false;

        // Test if the ray actually intersects the sphere
        float t = radSqr + v*v - dx*dx - dy*dy - dz*dz;
        if (t < 0) return false;

        // Test if the intersection is in the positive
        // ray direction and it is the closest so far
        t = v - ((float) Math.sqrt(t));
        if ((t > ray.t) || (t < 0))
            return false;

        ray.t = t;
        ray.object = this;
        return true;
    }