The overlay flushed into whatever framebuffer was bound last, which raised GL error 1286 on
every run: ov_flush now binds the screen and its viewport before it draws.
R3D_GLCHECK=1 checks each draw, clear, blit, upload and attachment for a pending error or an
incomplete framebuffer and names the target, and each sampler bind for a texture with no image
or a mipmap filter without mipmaps. Off, it costs one flag test.
Still open: an intermittent 1286 reported at "terrain shadow bake" after the self-tests (about
half the runs), and one macOS "unloadable" texture warning at shutdown while the post targets are
freed. No frame samples a bad texture.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Orkuncakilkaya
447acc11bd