Real-time 3D Character Animation with Visual C++

15	Using subdivision surfaces

Real-time 3D applications are limited to relatively few polygons to describe a model. On some machines displaying 5000 triangles, 25–30 times a second is the limit of the processor and graphic card capabilities; on other systems, a 50 000-polygon limit could be achieved. How do we scale the display to suit the hardware? One popular technique is to use subdivision surfaces. Using this method the original polygonal mesh is used as the basis for the model. With one pass of subdivision every edge is divided in two, so that each triangle is replaced with four triangles. If the new vertices are placed simply at the mid-point of the edge then the surface would not be smoothed, but if we could devise a way of placing ...