Triangles are the simplest form of polygons and they are also often used by 3D Engines. Crystal Space uses more general convex polygons. A room or object can be made by using polygons. For example, to make a cube you need six polygons. One polygon for every face of the cube.
Convex polygons are a special case of polygons.
All corners in a convex polygon are always less than 180 degrees. Direct3D, OpenGL, Glide, 3Dfx. Describe each in general terms and compare and contrast them. The company of the 3D cards often doesn't release the hardware specifications. Your program will only be compatible with the types of cards that you program.