From dee5943c0e2b300645401b421cb1698452b9298c Mon Sep 17 00:00:00 2001
From: Matthew Waters <matthew@centricular.com>
Date: Sun, 30 Nov 2014 00:18:55 +1100
Subject: [PATCH] glimagesink: properly handle the !opengl3 case

https://bugzilla.gnome.org/show_bug.cgi?id=740012
---
 ext/gl/gstglimagesink.c | 70 ++++++++++++++++++++++++++++++++++---------------
 ext/gl/gstglimagesink.h |  2 ++
 2 files changed, 51 insertions(+), 21 deletions(-)

diff --git a/ext/gl/gstglimagesink.c b/ext/gl/gstglimagesink.c
index bccff26..4df435e 100644
--- a/ext/gl/gstglimagesink.c
+++ b/ext/gl/gstglimagesink.c
@@ -1162,40 +1162,61 @@ static const GLfloat vertices[] = {
 };
 /* *INDENT-ON* */
 
-/* Called in the gl thread */
 static void
-gst_glimage_sink_thread_init_redisplay (GstGLImageSink * gl_sink)
+_bind_buffer (GstGLImageSink * gl_sink)
 {
   const GstGLFuncs *gl = gl_sink->context->gl_vtable;
-  int attr_position, attr_texture;
 
-  gl_sink->redisplay_shader = gst_gl_shader_new (gl_sink->context);
-
-  if (!gst_gl_shader_compile_with_default_vf_and_check
-      (gl_sink->redisplay_shader, &attr_position, &attr_texture))
-    gst_glimage_sink_cleanup_glthread (gl_sink);
-
-  gl->GenVertexArrays (1, &gl_sink->vao);
-  gl->BindVertexArray (gl_sink->vao);
-
-  gl->GenBuffers (1, &gl_sink->vertex_buffer);
   gl->BindBuffer (GL_ARRAY_BUFFER, gl_sink->vertex_buffer);
   gl->BufferData (GL_ARRAY_BUFFER, 4 * 5 * sizeof (GLfloat), vertices,
       GL_STATIC_DRAW);
 
   /* Load the vertex position */
-  gl->VertexAttribPointer (attr_position, 3, GL_FLOAT, GL_FALSE,
+  gl->VertexAttribPointer (gl_sink->attr_position, 3, GL_FLOAT, GL_FALSE,
       5 * sizeof (GLfloat), (void *) 0);
 
   /* Load the texture coordinate */
-  gl->VertexAttribPointer (attr_texture, 2, GL_FLOAT, GL_FALSE,
+  gl->VertexAttribPointer (gl_sink->attr_texture, 2, GL_FLOAT, GL_FALSE,
       5 * sizeof (GLfloat), (void *) (3 * sizeof (GLfloat)));
 
-  gl->EnableVertexAttribArray (attr_position);
-  gl->EnableVertexAttribArray (attr_texture);
+  gl->EnableVertexAttribArray (gl_sink->attr_position);
+  gl->EnableVertexAttribArray (gl_sink->attr_texture);
+}
+
+static void
+_unbind_buffer (GstGLImageSink * gl_sink)
+{
+  const GstGLFuncs *gl = gl_sink->context->gl_vtable;
 
-  gl->BindVertexArray (0);
   gl->BindBuffer (GL_ARRAY_BUFFER, 0);
+
+  gl->DisableVertexAttribArray (gl_sink->attr_position);
+  gl->DisableVertexAttribArray (gl_sink->attr_texture);
+}
+
+/* Called in the gl thread */
+static void
+gst_glimage_sink_thread_init_redisplay (GstGLImageSink * gl_sink)
+{
+  const GstGLFuncs *gl = gl_sink->context->gl_vtable;
+
+  gl_sink->redisplay_shader = gst_gl_shader_new (gl_sink->context);
+
+  if (!gst_gl_shader_compile_with_default_vf_and_check
+      (gl_sink->redisplay_shader, &gl_sink->attr_position,
+          &gl_sink->attr_texture))
+    gst_glimage_sink_cleanup_glthread (gl_sink);
+
+  if (gl->GenVertexArrays) {
+    gl->GenVertexArrays (1, &gl_sink->vao);
+    gl->BindVertexArray (gl_sink->vao);
+  }
+
+  gl->GenBuffers (1, &gl_sink->vertex_buffer);
+  _bind_buffer (gl_sink);
+
+  if (gl->GenVertexArrays)
+    gl->BindVertexArray (0);
 }
 
 static void
@@ -1208,7 +1229,8 @@ gst_glimage_sink_cleanup_glthread (GstGLImageSink * gl_sink)
     gl_sink->redisplay_shader = NULL;
   }
 
-  gl->DeleteVertexArrays (1, &gl_sink->vao);
+  if (gl_sink->vao)
+    gl->DeleteVertexArrays (1, &gl_sink->vao);
 }
 
 static void
@@ -1318,7 +1340,10 @@ gst_glimage_sink_on_draw (GstGLImageSink * gl_sink)
 
     gst_gl_shader_use (gl_sink->redisplay_shader);
 
-    gl->BindVertexArray (gl_sink->vao);
+    if (gl->GenVertexArrays)
+      gl->BindVertexArray (gl_sink->vao);
+    else
+      _bind_buffer (gl_sink);
 
     gl->ActiveTexture (GL_TEXTURE0);
     gl->BindTexture (GL_TEXTURE_2D, gl_sink->redisplay_texture);
@@ -1326,7 +1351,10 @@ gst_glimage_sink_on_draw (GstGLImageSink * gl_sink)
 
     gl->DrawElements (GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);
 
-    gl->BindVertexArray (0);
+    if (gl->GenVertexArrays)
+      gl->BindVertexArray (0);
+    else
+      _unbind_buffer (gl_sink);
   }
   /* end default opengl scene */
   window->is_drawing = FALSE;
diff --git a/ext/gl/gstglimagesink.h b/ext/gl/gstglimagesink.h
index 12d7293..e99fad9 100644
--- a/ext/gl/gstglimagesink.h
+++ b/ext/gl/gstglimagesink.h
@@ -90,6 +90,8 @@ struct _GstGLImageSink
     GstGLShader *redisplay_shader;
     GLuint vao;
     GLuint vertex_buffer;
+    GLint  attr_position;
+    GLint  attr_texture;
 };
 
 struct _GstGLImageSinkClass
-- 
2.7.4