IPUDOOM/NOTES.md

Things that are interesting about IpuDoom

• Fixed precision int math
  • 64-bit int division
    • wasn't supported in the supervisor context, drop into a worker thread for each individual division, do double division
• Avoid recursive algorithms, e.g. make a non-recursive BSP
• Split column rendering over 32 tiles
• Memory
  • Save 50-60k of lookup tabes for transcendentals by using float functions
  • Store textures on other tiles, JIT-fetch as needed (by live patching exchange programs to select a tile)
    • Can call exchanges from deep in the call stack, don't need to exit the vertex
    • Texture tiles also do colour mapping to create shadow effects (light dropoff)

Places could save memory

• Transcendental lookups -> live calc
• Move scalelight table from render tiles to texture tiles, include light level in column request. Saves 8K

Things I don't support, to make my life easier:

• gamemodes other than shareware
• multiplayer
• cheating