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.
The Far clipping plane did not need to be nearly as high as it was, the new value is 32768, which I suspect is about how far software can render before it completely falls apart.
It is desirable to increase the near clipping plane to between 6-10, but it can introduce more issues with close geometry not being drawn when the player or camera is scaled or viewheight is set to MIN in first person view. It would also stop sprites from being drawn ever so slightly too early, but this isn't too much of an issue and isn't too noticeable with those values. Might look into scaling near clipping plane in accordance to camera scale in the future.
The reason for wanting to increase the near clipping plane is because the small value can cause very noticeable Z-fighting where there shouldn't be on older GPU's, usually Intel ones, that don't support 24-bits for the depth buffer.
Draw Textures and Flats that have holes in them like a solid polygon so they use the depth buffer and don't need to be sorted
Disable all linear filtering on textures and flats that have holes in them, the linear filtering introduces translucency into the textures where the edges are. Leaving them with either a black border, or causing pixels behind the slightly translucent areas to not be drawn. Doesn't apply to sprites and the HUD as they are always already sorted properly.
Make the Alpha Testing more strict on non-translucent blend modes. This makes it so any transparency below 0.5 is discarded instead. Would make anything that is blended and has holes in it look slightly better, only the HUD and MD2s where the texture has holes are effected currently.
Set TF_TRANSPARENT on flat texture flags when there are holes in the texture.
Minor fix to make sure MD2s always set the right blend mode
OpenGL slope FOF lighting fix
This fixes some issues with sloped FOFs that affect lighting in OpenGL (as in, those that cast a shadow or have a colormap). Particularly, they can do strange things to any wall textures adjacent to them, as we've noticed ourselves in levels for 2.2. =P
See merge request !194
Polyobject segs should ONLY be drawn if the polyobject itself is in the polylist of a subsector being rendered. That way you won't sometimes see polyobject walls through level boundaries, if you happen to be close enough to their pre-spawn locations outside the level (or in them, if you decided to go on a noclip journey).
Some texture-related fixes
Bugs fixed in this branch:
* upper/lower/middle textures with non-existent texture ids being capable of crashing the game. For instance, RVZ1 has colormap codes on non-colormap linedefs, which causes them to wind up with invalid texture ids because of how the game tries to interpret lower/upper textures with "#" followed by characters on normal linedefs. Fortunately these "textures" are normally not visible anyway (since they're all in control sectors) unless they are swapped with in-level textures by some crazy Lua script of some sort...
* animated single-patch textures with holes displaying garbage on first viewing (see this thread: https://mb.srb2.org/showthread.php?t=42195)
* the heights of the lighting (shadows or colormapping) from water/translucent/shadowcasting/etc FOFs become messed up when displayed on repeated midtextures.
See merge request !144
