This mainly targets OpenGL ES 2.0 but it also supports compiling GLSL as
ESSL 3.00. It's missing support for framebuffer objects which should be
possible on ES 2. (Though using renderbuffers instead of textures.)
opengl1 cvars that are not supported will display a message and disable
the cvar. This has not been reviewed for new opengl2 cvars. Enabling
cvars may cause rendering issues. Some of the broken cvars may be
possible to support using OpenGL ES 3 features.
The game displays okay with the default cvars.
Don't draw the world scene to a separate FBO from the rest of the
screen.
This fixes the world scene having HOM instead of seeing through to the
previously drawn content. World of Padman uses this to have a separate
3D scene for the sky and world in wop_padship for dynamic skybox.
This also makes r_ext_framebuffer_multisample apply to HUD models
instead of depending on r_ext_multisample (which doesn't work on Linux
with some Intel graphics).
The game world is too dark when r_autoExposure is disabled. It can be
fixed by setting (cheat) r_cameraExposure to 1 but then the game is
too bright when r_autoExposure is enabled. So default r_cameraExposure
to 1 and make auto exposure subtract 1 from r_cameraExposure value.
