* Feature-complete isometric mode fork.
* Dithered transparency condition tweaks.
* Dithered transparency for non-corpse monsters only (and missiles).
* SpectatorCamera vertical shift.
* Including math.h in hw_sprites.cpp to keep visual studio happy (it couldn't find M_SQRT2 definition).
* Defining MY_SQRT2 in hw_sprites.cpp to keep visual studio happy (it couldn't find M_SQRT2 definition).
* Defining MY_SQRT2 in r_utility.cpp also to keep visual studio happy.
* retrigger checks
* Have correct sprite angle-frame face the camera with orthographic projection enabled.
* Dithered Transparency now works properly on 3D floors. Moved that dither-trans flag setting code within hw_bsp.cpp to handle double-processing of linedefs. Added helper functions to FRenderViewpoint class 'bool IsOrtho()' and 'bool IsAllowedOoB()' to clean up checks everywhere in the code.
* Fixed indents. Added bbox property to subsector struct and use it instead of BSP nodes and Clippers (creating a bbox around viewpoint and checking for overlap) in orthographic mode when no fog of war is active. Turns out to be much faster. Though you need really big maps (Winter's Fury MAP01) to see a difference in fps.
* Non-linux checks don't like uint. Changed to unsigned int.
* Small change of a float to camera.zs. Ignore for testing. Should make no difference.
* Update actor.h to remain mergeable
RF2_NOMIPMAP was introduced, so I had to displace RF_ISOMETRICSPRITES to next bit.
* remove duplicated fields
* make native functions use direct calls
* remove unnecessary pointer from particle_t
* create HWSprite directly in Construct
- Effectively similar to Actors, but without the excess.
- Can be created with either the `level` function or the static `Spawn` function in ZSprite.
- STAT_SPRITE belongs to ZSprites only; ZSprites cannot be moved out of, nor can anything else be moved in to, this statnum.
Misc:
- Fixed (Sprite)Offset taking roll into account.
Crediting phantombeta, RicardoLuis0 and RaveYard for assistance.
# draw upper and lower textures when the back sector does not properly match
# do not draw middle textures on portal lines
# minor optimization to 'is***Portal' functions to avoid memory access in the most common case of no portal being present.
