float3 xyY2XYZ( float3 _xyY ) { float Y_over_y = _xyY.z / _xyY.y; float3 XYZ; XYZ.x = _xyY.x * Y_over_y; XYZ.y = _xyY.z; XYZ.z = (1.0f - _xyY.x - _xyY.y) * Y_over_y; return XYZ; }