Matteo Bruni (@Mystral) commented about dlls/d3dx9_36/tests/surface.c:
+ } + release_surface_readback(&surface_rb); + + /* DXT surface without premultiplied alpha, colors match what was uploaded. */ + get_surface_decompressed_readback(device, surf, &surface_rb); + for (y = 0; y < 4; ++y) + { + for (x = 0; x < 4; ++x) + check_readback_pixel_4bpp(&surface_rb, x, y, src_pixels[(y * 4) + x], FALSE); + } + release_surface_readback(&surface_rb); + + /* + * Load the DXT block as a premultiplied alpha format. It's + * demultiplied on upload. + */ Another one of those nitpicks, sorry... "Demultiplied" is a bit of an awkward word (admittedly undoing the premultiplied alpha is an awkward operation in the first place, nothing we can do about that though). I don't have any great suggestion, maybe just spelling out the whole "reversing the premultiplication" in some way is fine (while pushing the naming issue to whenever it's time to implement it :sweat_smile:).
I guess the comment could mention explicitly that we're uploading the premultiplied alpha data into an uncompressed format surface. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/6360#note_80591