Both of these were inherited from ZDoomGL and in terms of light design in maps it makes absolutely no sense to have them user configurable. They should have been removed 11 years ago.
- restricted gl_lights_additive to legacy code and removed menu entry for this.
For modern hardware this setting is completely pointless, it offers no advantage and degrades visual quality. Its only reason for existence was that drawing additive lights with textures is a lot faster, and that's all it's being used for now.
Added gl_renderbuffers CVAR that disables render buffers
Added patch shader support to FShaderProgram
Added OpenGL 2 fallback support to render buffers
- removed gl_vid_compatibility. With the bump to 1.4 no hardware requiring this flag is supported anymore.
- disabled 16 bit framebuffers for the same reason. As a conseqence all code for rendering without stencil could also be removed.