Code was moved around between 3.8.0 and 19.0.0 which broke the colored backgrounds of paletted HUD gauges.
Palette index 15 is used by the HUD gauge graphics to indicate background area of HUD gauges. When the code to remap palette indexes to alpha values was moved to packunpack.cpp, palette index 15 was mistakenly mapped to the alpha for index 0 (nothing) rather than index 1 (what retail/3.8.0 code maps it to) causing all HUD gauges to be missing their dark transparent backgrounds.
Also: the code maps palette indexes [0, 15] to alpha values [0, 255]. But due to an oversight (palette index 15 not being part of this gradient] alpha value 255 is never used so the range of alpha values for HUD gauges ended up being [0, 238]. Conversion math tweaked to make the alpha range [0, 252] which is very close to 255.
Currently, the graphics code does some color remapping on 8
bit-per-pixel textures since those textures use special 4-bit pixel
values. These changes move that conversion out of the graphics code and
into the image loading/font bitmap creation code.
The reason this is needed is because this conversion breaks 8-bit
textures that try to use the full range of colors. I need to do exactly
that for moving the cutscene renderer to our generic rendering interface
which I can't do at the moment since the existing color conversion
corrupts the video data.
I have tested this with retail data and could not find any visual
changes after applying these changes.
OK, these changes effect a lot of file, I suggest everyone updates ASAP:
Removal of many files from project.
Removal of meanless Gr_bitmap_poly variable.
Removal of glide, directdraw, software modules all links to them, and all code specific to those paths.
Removal of redundant Fred paths that arent needed for Fred OGL.
Have seriously tidied the graphics initialisation code and added generic non standard mode functionality.
Fixed many D3D non standard mode bugs and brought OGL up to the same level.
Removed texture section support for D3D8, voodoo 2 and 3 cards will no longer run under fs2_open in D3D, same goes for any card with a maximum texture size less than 1024.
Also 32 bit PCX, but it still has some bugs to be worked out
Moved convert_24_to_16 out of the bitmap pfunction structures and into packunpack.cpp because thats the only place that uses it.
bangstk