fn intersect_tri(ray: &Ray, v0: Vector4, v1: Vector4, v2: Vector4) -> (f32, f32, f32) {
    const EPSILON : f32 = 0.00000000001;

    let e1 = v1 - v0;
    let e2 = v2 - v0;

    //Begin calculating determinant - also used to calculate u parameter
    let p = ray.dir.cross3(e2);

    let det = e1.dot3(p);

    //if determinant is near zero, ray is parallel to plane of triangle
    if det > -EPSILON && det < EPSILON {
        return (NO_INTERSECTION, 0.0, 0.0);
    }
    let inv_det = 1.0 / det;

    // Calculate distance from V0 to ray origin
    let t = ray.org - v0;

    // Calculate u parameter and test bound
    let u = t.dot3(p)* inv_det;

    // The intersection lies outside of the triangle
    if u < 0.0 || u > 1.0 {
        return (NO_INTERSECTION, 0.0, 0.0);
    }

    // Prepare to test v parameter
    let q = t.cross3(e1);

    // Calculate V parameter and test bound
    let v = ray.dir.dot3(q)*inv_det;

    // The intersection lies outside of the triangle
    if v < 0.0 || u + v  > 1.0 {
        return (NO_INTERSECTION, 0.0, 0.0);
    }

    let t = e2.dot3(q)*inv_det;

    if t > EPSILON { //ray intersection
        return (t, u, v);
    }

    return (NO_INTERSECTION, 0.0, 0.0);
}