(By that, I mean it defaults to ASM, but uses the C version when drawing brightmapped stuff. Was this worth the minor performance gain over just making NOASM=1 default? I dunno.)
* Set via a fourth digit in the upper midtexture for transparent FOFs
* For example - #2551 is additive solid, #1282 is subtractive half...
* The original method of setting the upper midtexture to #900 or 901 still works, since I'm not out to break existing maps.
* Software: Remove the horrible `else if` ladder for FOF translucency. Algorithms, baby!
* OpenGL: Move to using `HWR_GetBlendModeFlag` in more places, for more long-term extensible support for multiple blendmodes.
All my work thus far on solving the drawflag/renderflag/additive/subtractive conundrum.
Outstandng problems:
* Bad additive/subtractive tables means that they appear opaque except under certain conditions.
* No support for FOFs, Polyobjects, or linedefs in OpenGL yet.
* All OpenGL support mostly done blind, may or may not function in practice.
If nothing else, the hard engineering problems are solved and it's just bug hammering...
Polyobjects set translucency to 11 for additive, and 12 for subtractive
FOFs using the regular translucency settings set the top texture to #900 for additive, and #901 for subtractive
Object tracking is off, but it was off before so I don't know if I actually
broke it. Minor refactoring in HWR_RenderPlayerView and HWR_RenderSkyboxView.
Fake contrast for the segs are calculated at map load.
OpenGL only has the options "Standard" and "Smooth" now. Standard is default and replicates software. Smooth changes the contrast more smoothly depending on angle.
* Replace the texheight parameter provided directly to it with a previously existing (now renamed) global used for the same purpose, so that it can be used as an interchangeable function pointer with R_DrawMaskedColumn.
* Using the above, optimise R_DrawVisSprite to call a function pointer in a tighter loop rather than check SC_VFLIP each time around.
* SHORT macro can involve repeated operations; calculate once and put in memory for both RANGECHECK and papersprite.
* Remove irrelevant range check (already covered by existing range check immediately above) from R_DrawFlippedMaskedColumn and R_DrawMaskedColumn.
* "Warning: avoiding a crash in %s %d" is a terrible error message, and it chips away at the tightness of the loop just for something most people will never see printed. Replace with a PARANOIA I_Error in case someone actively wants to go hunting for its cause.
