It's a real mess in places, mainly in the way it loads level geometry. DirectX initialisation is hard-coded with no fallback code if some feature is missing or unsupported.
DOOM DOOM2.WAD MAP31
DOOM DOOM.WAD E1M3
DOOM TNT.WAD MAP03
Keys: use the cursor keys to move around, A and Z to move up and down.
- Floor splitting is abysmal. It is highly inefficient and occasionally wrong. The floor splitting code breaks sectors into horizontal spans which it then splits into triangles - uneven vertex placement results in largish cracks between sectors or "hairline" dancing-pixel cracks inside sectors. Large holes are usually the case of a sector that "overflows" another one. Ideally; decode floors via ssector/seg information or just use glBSP.
- Timing (level animation) is done via the primitive Timer class. If something starts to hog CPU time, the timers all slow down leading to inconsistent animation speeds.
- Scrolling walls and light effects are controlled differently; sector light effects (which affect a large amount of geometry) save the vertex array written to the vertex buffer away; this array is changed then sent to a vertex buffer, overwriting the existing data. The scrolling walls (affect a small amount of geometry) read the vertex buffer, alter the texture coordinates, then write it back. This results in a confict; if a linedef has both scrolling AND lighting effects, every time the light level changes the scroll offset is reset to the original linedef's value.
- Skies that occlude geometry that is visible normally aren't handled correctly.
- Player start angle is occasionally backwards.
- Some of the more bizarre walls still don't display properly.