After more than three partial readbacks of one buffer in a frame,
ReadFramebufferToMemory read the whole buffer instead for the rest of the
session, writing rows the game never asked for.
Everybody's Golf 2 reads back four portraits' color and depth per frame, which
turned it on. The whole 480x273 depth buffer then got written to VRAM, and its
last row is where the game keeps its texture heap. A texture header was
overwritten: the portrait showed the scene behind it, and the next time the
portraits were built the game crashed writing through a null pointer.
It was added for speed in Grand Knights History (c42d04829f), which copies many
slivers of a framebuffer, so that game may now do more readbacks.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
