cube mapping is a method of environment mapping that uses the six faces of a cube as the map shape. The environment is projected onto the sides of a cube and stored as six square textures, or unfolded into six regions of a single texture. The cube map can then be sampled to create reflections which look like they are in the scene.
To get reflections from cube map, first we find the reflected ray of the one from camera to screen. We use the hlsl function reflect() for that. Once we get the reflected ray, we sample the cubemap at that location to get the desired reflection. This can be seen in screenshots below.
Update: I made a mistake when calculating the reflected fresnel equation. Instead of using the reflected vector from camera, i was using the normal vector which was causing the white out you can see below. I’ve added a new video after the screenshot which shows the correct reflections.
Metals have a very high reflection value and also reflect light in such a way that the reflected light has the same color as the metal. So we have to multiply the value of color to both the sampled data from environmental map and the specular light. Metals do not have diffuse light because of their high reflectance, so we can ignore that value. You can see the gold shader below. The while point at the center is the specular highlight from the direction light