[hkmodd]

Summary

The texture cache checked every 600 frames for textures not drawn in the last 1800 frames and dropped them. At 60 frames a second that is a check every ten seconds and a drop after half a minute. At 360 frames a second it is a drop after five seconds:

• looking away from part of a level for five seconds dropped its textures;
• turning back converted and uploaded them again;
• the faster the display, the more often this happened.

On b30 at 357 frames a second, 105 textures were dropped in 38 seconds of play.

With this change the cache counts time instead of frames:

• it sweeps every 10 seconds, timed with SDL_GetTicks (the Android guest bridges it and the web has it);
• each sweep drops the textures not drawn since the sweep three sweeps earlier, so a texture goes 30 to 40 seconds after it was last drawn, as it did at 60 frames a second;
• the frame counter still orders the palette variants.

Testing

tools/harness/tests/test_texture_idle.py runs xgpu_texture_cache_begin_frame, taken from the sources, against a fake clock. In every case a texture drawn every frame is never dropped.

Case	Frame rate	Hidden texture last drawn	Required drop
fast	360 fps	at 1 s	30–40 s later
steady	60 fps	at 1 s	30–40 s later, as before
late	360 fps	at 25 s, after several sweeps	30–40 s later

On main, fast and late fail: the texture is dropped after 5.7 and 6.7 seconds. steady passes on main.

Four negative controls, each expected to fail one case:

Mutation	Fails
A sweep every frame	fast
The sweep's own frame taken as the earlier one	fast
Sweeps not counted	late
A 60 s idle time	steady

xbox_textures.c compiles without warnings in the Windows release build.

Not checked:

• Time saved in play. Not measured. Each upload took 1.6 ms or less on an RTX 4080; the saving is larger where conversion and uploads cost more.
• Linux, Android and web builds. Not compiled: the fork's CI is unavailable, and this machine has no Linux sysroot or Emscripten. The change uses only SDL_GetTicks, which the Android guest bridges (guest_sdl.c) and the other builds get from SDL3.

🤖 Generated with Claude Code