However, why do we know that their foreheads are actually furrowed instead of being painted with some light and dark lines? After all, this is just a flat painting. The furrowed brows of the apostles not only symbolize this incredulity but clearly convey it by means of a common facial expression. The painting by Caravaggio that is depicted to the left is about the incredulity of Saint Thomas, who did not believe in Christ's resurrection until he put his finger in Christ's side. The code of this tutorial is based on the tutorial on smooth specular highlights and the tutorial on textured spheres.
In this tutorial, we start with normal mapping, which is a very well established technique to fake the lighting of small bumps and dents - even on coarse polygon meshes. It's the first of two tutorials about texturing techniques that go beyond two-dimensional surfaces (or layers of surfaces). “The Incredulity of Saint Thomas” by Caravaggio, 1601–1603.
