We now dereference the pointer given to us before adding the arguments
to an active list. This also factors out the switching logic from the
API wrappers, which helps us with a future commit where we autogenerate
all API wrapper functions.
We do not need to templatize the output type - it's always `float`.
Also, the input type can be inferred. Finally, use template
specialization instead of a conditional to deal with same type input and
output matrices.
When compiling with SDL_opengl, all kinds of differences between LibGL
and OpenGL constants and types popped up as redefinition warnings and
errors.
This fixes all LibGL-related warnings when compiling PrBoom+ :^)
This commit implements glClipPlane and its supporting calls, backed
by new support for user-defined clip planes in the software GPU clipper.
This fixes some visual bugs seen in the Quake III port, in which mirrors
would only reflect correctly from close distances.
We were splitting these API wrappers up into different files without a
quantifiable benefit. Now, it's extremely clear where the direct API
implementation lives. :^)
