Computing MIP Levels From Specular Power/Roughness To compute MIP level from specular power/roughness you need to have the number of MIP levels in the cube map available in your shader. If you are developing in HLSL then you can get hold of it using GetDimensions() and if you are using GLSL then you can use textureQueryLevels(). If you are developing in a shader language where you do not have acce