Games often use the framebuffer alpha channel for non-visual purposes,
so saved PNGs could look fully transparent in image viewers. Force alpha
to 255 when writing PNG screenshots unless --screenshot-keep-alpha is
passed. The MSE comparison ignores alpha either way.
- Add frametests.py: walks a dump tree, renders each dump per config variant
through PPSSPPHeadless, generates reference images when missing and compares
MSE when present, and writes a self-contained HTML report. The JSON config
(which lives with the test set, not in the repo) points at the data tree
and defines variants as suffix -> CLI args, e.g. 'soft': '--graphics=software'.
- Headless: --screenshot-save saves PNG when the path ends in .png; new
--screenshot-diff always writes a visual comparison when comparing;
screenshot comparison failures (mismatch or unloadable reference) now fail
the test instead of passing silently.
- Read back framebuffers top-down, flipping only for BMP output/input
(fixes upside-down PNG references). Sync libretro copy accordingly.
- Document the system in docs/frametest.md; add AGENTS.md reference.
Henrik Rydgård