In this recipe, we will implement a simple technique for the local refinement of triangle meshes through tessellation—Phong tessellation. This technique, put forward by Boubekeur and Alexa in 2008, follows the same principles as Phong shading (thus the name) and normal mapping, but instead of improving the perceived visual smoothness of flat surfaces, it improves the actual smoothness of contours and silhouettes.

Phong tessellation is computationally inexpensive when compared to algorithms for approximating Catmull-Clark subdivision surfaces. It still achieves smooth silhouettes and more importantly, it can be locally implemented on the tessellation hardware without requiring any additional precalculated weights/control points or specially prepared meshes unlike bicubic Bezier patches or Gregory patches.

This means that most existing triangulated meshes will work reasonably well with Phong tessellation with few or no changes to the original mesh.