I am confused in regards to this. From my understanding, a bump map sort of 'overrides' the normals provided by the mesh faces for lighting calculations.
I also know that in flat-shading, a pixel is shaded based on color calculated with the normal of its face only, while smooth-shading interpolates the normals calculated at each vertex per pixel and shades the pixel accordingly. As such, flat shaded faces have the same color throughout while smooth-shaded dont
A bump/normal map essentially shades the triangle per pixel just like smooth shading, but the normal used is taken from the map/texture as opposed to some linearly interpolated vertex normal. So logically, since normal/bump maps do this overriding of the normals to be used for shading, one would expect that a smooth-shaded bump map model should look identical to a flat-shaded bump-mapped one
After all, in both a smooth and flat shaded bump mapped normal, the bump map overides the normal in both cases.
Yet here is what a smooth-shaded Bump mapped Suzzane looks like:
And this is what a flat-shaded bump mapped Suzzane looks like:
The difference is very subtle but it is indeed there. What exactly causes them both to look different? Isnt a bump map overriding the mesh normals in each case?