Other notes:
* on second thought I'll keep the hw_clip functions' gld prefixes rather than HWR, not like it matters either way
* despite the extra lag it does fix the issues with translucent walls and such when displayed at different vertical angles, such as with the GFZ1 waterfall
Also tweaked a weird splitscreen check in HWR_DrawSpriteShadow; still investigating whether stplyr is ever not player 2 when it's player 2's view, but this looks better for now
Move old fix for too large maps having rendering issues from R_CheckBBox to OpenGL's HWR_CheckBBox
From what I know, this effects at least Aerial Garden and Seraphic Skylands
I don't fully understand this, but it's what software does and it fixes the issue of the lighting in DSZ3. Also don't need the extra call to R_Prep3DFloors.
Transformation based on screen space would make sense if we didn't want anything in the world to effect the sprites.
This should allow sprite splitting and sorting of sprites with level geometry easier.
stransform is no longer needed.
Solid walls *can* be cut
Fix issues with water and fog FOFs not cutting each other out correctly
Fix Fog colourmap and lighting setting that is done here.
Remove HWR_SplitFog
There is currently a bug with FF_DOUBLESHADOW (that also exists in software) but has a larger impact here. When 2 FF_DOUBLESHADOW lights are directly stacked on each other the bottom one has its height set incorrectly. This causes all the Fog in the timed gravity flipping section of ERZ2 to be drawn and it looks really bad.
They still aren't perfect, but now they are at least not quite so obviously just translucent polygons over the level. A mixture between partially modulating the background colours and adding the fog colour. Notably white fog blocks look like they're brightening what's behind them.
Additive was also setting noalphatest before, can probably decide that depending on what it needs anyway. I don't think it's currently used anyway.
Sorts all translucent sprites and MD2s so they're drawn after all the opaque ones. Fixes most of the observable issues between translucent MD2s and opaque sprites/MD2s.
Only use glCopyTexImage2D when first creating the screen texture, use glCopyTexSubImage2D anytime after that as it does not define a new texture each time.
Flushing of the screen textures has been implemented for when the screen size changes (so that the screen textures don't stay at a wrong size) and the game is closed, I believe they would leave a memory leak before.
