bool triIntersect(float3 v0, float3 v1, float3 v2, ray_t ray, float *tmin)
{
    float3 a = v0 - v1;
    float3 b = v2 - v0;
    float3 p = v0 - ray.pos;
    float3 n = cross(b, a);
    float3 q = cross(p, ray.dir);

    float idet = 1.0 / dot(ray.dir, n);

    float u = dot(q, b) * idet;
    float v = dot(q, a) * idet;
    float t = dot(n, p) * idet;

	*tmin = t;
    return !(u < 0.0 || u > 1.0 || v < 0.0 || (u + v) > 1.0) && t > 0.0;
}