modulo operator could be used to check if size is multiple of a
certain number.
equal operator could be used to verify if size of different textures
aligns.
This has several advantages:
1. no more redundant texcoords when we don't need them
2. no more arbitrary limit on how many textures we can bind
3. (that extends to user shaders as well)
4. no more arbitrary limits on tscale radius
To realize this, the VAO was moved from a hacky stateful approach
(gl_sc_set_vertex_attribs) - which always bothered me since it was
required for compute shaders as well even though they ignored it - to be
a proper parameter of gl_sc_dispatch_draw, and internally plumbed into
gl_sc_generate, which will make a (properly mangled) deep copy into
params.vertex_attribs.
This is done in several steps:
1. refactor MPGLContext -> struct ra_ctx
2. move GL-specific stuff in vo_opengl into opengl/context.c
3. generalize context creation to support other APIs, and add --gpu-api
4. rename all of the --opengl- options that are no longer opengl-specific
5. move all of the stuff from opengl/* that isn't GL-specific into gpu/
(note: opengl/gl_utils.h became opengl/utils.h)
6. rename vo_opengl to vo_gpu
7. to handle window screenshots, the short-term approach was to just add
it to ra_swchain_fns. Long term (and for vulkan) this has to be moved to
ra itself (and vo_gpu altered to compensate), but this was a stop-gap
measure to prevent this commit from getting too big
8. move ra->fns->flush to ra_gl_ctx instead
9. some other minor changes that I've probably already forgotten
Note: This is one half of a major refactor, the other half of which is
provided by rossy's following commit. This commit enables support for
all linux platforms, while his version enables support for all non-linux
platforms.
Note 2: vo_opengl_cb.c also re-uses ra_gl_ctx so it benefits from the
--opengl- options like --opengl-early-flush, --opengl-finish etc. Should
be a strict superset of the old functionality.
Disclaimer: Since I have no way of compiling mpv on all platforms, some
of these ports were done blindly. Specifically, the blind ports included
context_mali_fbdev.c and context_rpi.c. Since they're both based on
egl_helpers, the port should have gone smoothly without any major
changes required. But if somebody complains about a compile error on
those platforms (assuming anybody actually uses them), you know where to
complain.
