bool Triangle::intersect(Ray ray){
    Vec3 direction = ray.direction;
    Vec3 origin = ray.origin;
    Vec3 v0v1 = v1 - v0;
    Vec3 v0v2 = v2 - v0;
    Vec3 pvec = Vec3::cross(direction, v0v2);
    float det = Vec3::dot(v0v1, pvec);

    // if det is negative then triangle is backfacing
    if(det<0.0001) return false;

    if(fabs(det)<0.0001) return false;

    float inv_det = 1.0/((float)det);

    Vec3 tvec = origin - v0;
    u = Vec3::dot(tvec, pvec) * inv_det;
    if (u < 0 || u > 1) return false;

    Vec3 qvec = Vec3::cross(tvec, v0v1);
    v = Vec3::dot(direction, qvec) * inv_det;
    if (v < 0 || u + v > 1) return false;

    t = Vec3::dot(v0v2, qvec);

    return true;
}