vo_opengl: restore single pass optimization as separate code path

The single path optimization, rendering the video in one shader pass and
without FBO indirections, was removed soem commits ago. It didn't have a
place in this code, and caused considerable complexity and maintenance
issues.

On the other hand, it still has some worth, such as for use with
extremely crappy hardware (GLES only or OpenGL 2.1 without FBO
extension). Ideally, these use cases would be handled by a separate VO
(say, vo_gles). While cleaner, this would still cause code duplication
and other complexity.

The third option is making the single-pass optimization a completely
separate code path, with most vo_opengl features disabled. While this
does duplicate some functionality (such as "unpacking" the video data
from textures), it's also relatively unintrusive, and the high quality
code path doesn't need to take it into account at all. On another
positive node, this "dumb-mode" could be forced in other cases where
OpenGL 2.1 is not enough, and where we don't want to care about versions
this old.

1 files changed, 1 insertions, 0 deletions

diff --git a/video/out/gl_video.h b/video/out/gl_video.h
index ef6ed76554..e8f8ffa030 100644
--- a/video/out/gl_video.h
+++ b/video/out/gl_video.h
@@ -71,6 +71,7 @@ struct gl_video_opts {
     char *scale_shader;
     char **pre_shaders;
     char **post_shaders;
+    int dumb_mode;
 };
 
 extern const struct m_sub_options gl_video_conf;