From 37eb6a0de0399ff005f67281beafc657fa7ed964 Mon Sep 17 00:00:00 2001
From: Vasily Khoruzhick <anarsoul@gmail.com>
Date: Mon, 13 Jul 2026 16:35:14 -0700
Subject: [PATCH] vo_gpu: opengl: support GL_EXT_framebuffer_object

Some GL 2.1 drivers (e.g. Mesa lima) expose GL_EXT_framebuffer_object
but not GL_ARB_framebuffer_object, leaving MPGL_CAP_FB unset even
though FBOs are usable. Load the EXT entrypoints as an alternative
provider of MPGL_CAP_FB; mpv's FBO usage (Gen'd names, GL_FRAMEBUFFER
target, single color attachment, runtime completeness checks) is
within the subset EXT and ARB share. The section is placed before the
ARB/core one so the latter overwrites the function pointers whenever
it is available.

Querying attachment parameters of the default framebuffer is an
ARB/GL 3.0 addition, so skip that query in ra_gl_ctx_color_depth()
when only the EXT extension is present.
---
 video/out/opengl/common.c  | 20 ++++++++++++++++++++
 video/out/opengl/context.c |  6 ++++++
 2 files changed, 26 insertions(+)

diff --git a/video/out/opengl/common.c b/video/out/opengl/common.c
index a5de79c901..9357674353 100644
--- a/video/out/opengl/common.c
+++ b/video/out/opengl/common.c
@@ -212,6 +212,26 @@ static const struct gl_functions gl_functions[] = {
         .extension = "GL_EXT_unpack_subimage",
         .provides = MPGL_CAP_ROW_LENGTH,
     },
+    // Framebuffers, alternative extension name. Some GL 2.1 drivers (e.g.
+    // Mesa lima) expose only this one. It provides a compatible subset of
+    // GL_ARB_framebuffer_object for our purposes; the entrypoints loaded
+    // here are overwritten by the ARB/core ones below if available.
+    {
+        .ver_exclude = 300,
+        .ver_es_exclude = 200, // FBOs are core in ES2
+        .extension = "GL_EXT_framebuffer_object",
+        .provides = MPGL_CAP_FB,
+        .functions = (const struct gl_function[]) {
+            DEF_FN_NAME(BindFramebuffer, "glBindFramebufferEXT"),
+            DEF_FN_NAME(GenFramebuffers, "glGenFramebuffersEXT"),
+            DEF_FN_NAME(DeleteFramebuffers, "glDeleteFramebuffersEXT"),
+            DEF_FN_NAME(CheckFramebufferStatus, "glCheckFramebufferStatusEXT"),
+            DEF_FN_NAME(FramebufferTexture2D, "glFramebufferTexture2DEXT"),
+            DEF_FN_NAME(GetFramebufferAttachmentParameteriv,
+                        "glGetFramebufferAttachmentParameterivEXT"),
+            {0}
+        },
+    },
     // Framebuffers, extension in GL 2.x, core in GL 3.x core.
     {
         .ver_core = 300,
diff --git a/video/out/opengl/context.c b/video/out/opengl/context.c
index cd76e1c5f8..9b8cabfe8c 100644
--- a/video/out/opengl/context.c
+++ b/video/out/opengl/context.c
@@ -193,6 +193,12 @@ int ra_gl_ctx_color_depth(struct ra_swapchain *sw)
     if ((gl->es < 300 && !gl->version) || !(gl->mpgl_caps & MPGL_CAP_FB))
         return 0;
 
+    // The *_SIZE attachment queries need GL_ARB_framebuffer_object or
+    // GL 3.0+; GL_EXT_framebuffer_object does not provide them.
+    if (gl->version && gl->version < 300 &&
+        !gl_check_extension(gl->extensions, "GL_ARB_framebuffer_object"))
+        return 0;
+
     gl->BindFramebuffer(GL_FRAMEBUFFER, p->main_fb);
 
     GLenum obj = gl->version ? GL_BACK_LEFT : GL_BACK;