vo_opengl: add a --opengl-es=force2 option

Useful for testing. Unfortunately, the nVidia EGL driver ignores this,
and returns a GLES 3.2 context anyway (which it is allowed to do). Might
still be useable with ANGLE, which will really give you a GLES 2 context
if you ask for it.

4 files changed, 11 insertions, 3 deletions

diff --git a/DOCS/man/options.rst b/DOCS/man/options.rst
index 98bb0455ad..4a0544d03a 100644
--- a/DOCS/man/options.rst
+++ b/DOCS/man/options.rst
@@ -4451,6 +4451,8 @@ The following video options are currently all specific to ``--vo=opengl`` and
 
     yes
         Try to prefer ES over Desktop GL
+    forc2
+        Try to request a ES 2.0 context (the driver might ignore this)
     no
         Try to prefer desktop GL over ES
     auto
diff --git a/video/out/opengl/context.h b/video/out/opengl/context.h
index ecb9d9c033..92b9da0432 100644
--- a/video/out/opengl/context.h
+++ b/video/out/opengl/context.h
@@ -27,12 +27,13 @@
 #include "common.h"
 
 enum {
-    VOFLAG_GLES         = 1 << 0,       // Hint to create a GLES2 context
+    VOFLAG_GLES         = 1 << 0,       // Hint to create a GLES context
     VOFLAG_NO_GLES      = 1 << 1,       // Hint to create a desktop GL context
     VOFLAG_GL_DEBUG     = 1 << 2,       // Hint to request debug OpenGL context
     VOFLAG_ALPHA        = 1 << 3,       // Hint to request alpha framebuffer
     VOFLAG_SW           = 1 << 4,       // Hint to accept a software GL renderer
     VOFLAG_PROBING      = 1 << 6,       // The backend is being auto-probed.
+    VOFLAG_GLES2        = 1 << 7,       // Hint for GLESv2 (needs VOFLAG_GLES)
 };
 
 extern const int mpgl_preferred_gl_versions[];
diff --git a/video/out/opengl/egl_helpers.c b/video/out/opengl/egl_helpers.c
index 2ed1fd44d6..d1ebd9aeca 100644
--- a/video/out/opengl/egl_helpers.c
+++ b/video/out/opengl/egl_helpers.c
@@ -181,12 +181,14 @@ bool mpegl_create_context_opts(EGLDisplay display, struct mp_log *log,
             return true;
     }
 
-    if (try_gles) {
+    if (try_gles && !(opts->vo_flags & VOFLAG_GLES2)) {
         // ES 3.x
         if (create_context(display, log, true, 3, opts,
                            out_context, out_config))
             return true;
+    }
 
+    if (try_gles) {
         // ES 2.0
         if (create_context(display, log, probing, 2, opts,
                            out_context, out_config))
diff --git a/video/out/vo_opengl.c b/video/out/vo_opengl.c
index 419631a0df..a1b9f6a75b 100644
--- a/video/out/vo_opengl.c
+++ b/video/out/vo_opengl.c
@@ -373,6 +373,8 @@ static int preinit(struct vo *vo)
 
     if (p->opts.es == 1)
         vo_flags |= VOFLAG_GLES;
+    if (p->opts.es == 2)
+        vo_flags |= VOFLAG_GLES | VOFLAG_GLES2;
     if (p->opts.es == -1)
         vo_flags |= VOFLAG_NO_GLES;
 
@@ -437,7 +439,8 @@ const struct vo_driver video_out_opengl = {
         OPT_STRING_VALIDATE("opengl-backend", opts.backend, 0,
                             mpgl_validate_backend_opt),
         OPT_FLAG("opengl-sw", opts.allow_sw, 0),
-        OPT_CHOICE("opengl-es", opts.es, 0, ({"no", -1}, {"auto", 0}, {"yes", 1})),
+        OPT_CHOICE("opengl-es", opts.es, 0, ({"no", -1}, {"auto", 0},
+                                             {"yes", 1}, {"force2", 2})),
         OPT_INTPAIR("opengl-check-pattern", opts.pattern, 0),
         OPT_INTRANGE("opengl-vsync-fences", opts.vsync_fences, 0,
                      0, NUM_VSYNC_FENCES),