90s demo effects ported to WebGL
Posted: Wed Jun 17, 2026 11:45 am
Spinning this off so I don't derail the .MOD thread. Based on this static dissection of DOPE by Complex (1st PC demo at TG'95, MS-DOS, 320×200 mode 13h): https://demo2.jeskola.net/dope-analysis.html
Rebuilt its effects live in WebGL (attached). All the real-mode tricks are toggles: fixed-point 3×3 rotation, divide-by-depth projection, radix polygon sort, additive overlays, nibble/palette hacks. Two-pass like the original — 320×200 work buffer → fake "VGA blit" with palette ramp + scanlines. Plus 4K/retina upscale (up to ×8 internally) with a chunky-pixels switch.
The analysis driven on a GPU instead of a 486 took the LLM about 5 minutes. Perfect as a starting point for audio visuals.
Rebuilt its effects live in WebGL (attached). All the real-mode tricks are toggles: fixed-point 3×3 rotation, divide-by-depth projection, radix polygon sort, additive overlays, nibble/palette hacks. Two-pass like the original — 320×200 work buffer → fake "VGA blit" with palette ramp + scanlines. Plus 4K/retina upscale (up to ×8 internally) with a chunky-pixels switch.
The analysis driven on a GPU instead of a 486 took the LLM about 5 minutes. Perfect as a starting point for audio visuals.