Needs to be tested in gravity flip
Also flips the normal on linedef based slopes so that it's facing the correct direction
Also makes it so slopelaunch doesn't always remove the standingslope (going down some slopes would cause it to be constantly unset and reset)
This should hopefully alleviate the issue where textures overwrite the screen, or the screen overwrites the texture for now.
THIS IS NOT A FULL SOLUTION TO THE PROBLEM, but I highly doubt we'll ever be loading 4 billion textures at once, ever.
This reverts commit 83d4f29367.
The reason I am reverting this is because the last commit actually fixes the *old* screenshot functionality, as the screen is being drawn back onto the buffer after they're swapped in the "real" size. Meaning the old function actually works perfectly fine now.
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.
Also removed the + 1 from newtime, since there was never really any need for it. It just offset the interpolation so it went like (1 -> 2] instead of [1 -> 2), so you never saw the base appearance for each frame except at the end of any frames interpolating to it
Changed DrawMD2Ex's duration/tics type to INT32 so -1 comparisons work, probably want to change the signs elsewhere too but this is fine for now
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
