The texture has a general blue tone because overall, the normal is towards the “outside of the surface”. Normal = ( 2 * color ) - 1 // on each component In each RGB texel is encoded a XYZ vector : each colour component is between 0 and 1, and each vector component is between -1 and 1, so this simple mapping goes from the texel to the normal : The basic idea of normal mapping is to give normals similar variations. One caveat is that until now, we only had one normal per vertex : inside each triangle, they vary smoothly, on the opposite to the colour, which samples a texture. Since Tutorial 8 : Basic shading, you know how to get decent shading using triangle normals. Welcome for our 13th tutorial ! Today we will talk about normal mapping.
