float _vectorToDepth(float3 vec, float n, float f)
{
    float3 AbsVec = abs(vec);
    float LocalZcomp = max(AbsVec.x, max(AbsVec.y, AbsVec.z));

    float NormZComp = (f+n) / (f-n) - (2*f*n)/(f-n)/LocalZcomp;
    return (NormZComp + 1.0) * 0.5;
}