Z-buffered polygons demo.
This program demonstrates how to use Z-buffered polygons and
floating point 3D math routines. It also provides a simple
way to compute fps (frames per second) using a timer. After
selecting a screen resolution through the standard GUI dialog,
the example shows two 3D cubes rotating and intersecting each
other. Rather than having full polygons incorrectly overlap
other polgons due to per-polygon sorting, each pixel is drawn
at the correct depth.