QAS (Quadratic Approximation Subdivision) Direct3D Demo
Patch Tesselation is a technique to increase in real time the number of triangles of a mesh. The principle is to use a coarse mesh at the CPU level and to add detail on-the-fly at the GPU level. The detail is added using a tesselation patch called refinement pattern and for each triangle of the coarse mesh the refinement pattern is rendered. Refinement pattern has the same shape than a single triangle of the coarse mesh but has a variable number of triangles according to the appropriate level-of-detail.
OpenGL Instanced Tesselation Demo