glmemory: Only use glDrawBuffer if available

Otherwise fall back to glDrawBuffers. Also check if glReadBuffer exists
before using it.

glDrawBuffer does not exist for GLES, only glDrawBuffers does.

https://bugzilla.gnome.org/show_bug.cgi?id=782376

diff --git a/gst-libs/gst/gl/gstglmemory.c b/gst-libs/gst/gl/gstglmemory.c
index 5e69321..343a859 100644 (file)
--- a/gst-libs/gst/gl/gstglmemory.c
+++ b/gst-libs/gst/gl/gstglmemory.c
@@ -672,7 +672,8 @@ gst_gl_memory_copy_teximage (GstGLMemory * src, guint tex_id,
       "texture %i", src, src_tex_id, tex_id);
 
   /* FIXME: try and avoid creating and destroying fbo's every copy... */
-  if (!gl->BlitFramebuffer) {
+  if (!gl->BlitFramebuffer || (!gl->DrawBuffer && !gl->DrawBuffers)
+      || !gl->ReadBuffer) {
     /* create a framebuffer object */
     n_fbos = 1;
     gl->GenFramebuffers (n_fbos, &fbo[0]);
@@ -696,6 +697,12 @@ gst_gl_memory_copy_teximage (GstGLMemory * src, guint tex_id,
 
     gl->DeleteFramebuffers (n_fbos, &fbo[0]);
   } else {
+    GLenum multipleRT[] = {
+      GL_COLOR_ATTACHMENT0,
+      GL_COLOR_ATTACHMENT1,
+      GL_COLOR_ATTACHMENT2
+    };
+
     /* create a framebuffer object */
     n_fbos = 2;
     gl->GenFramebuffers (n_fbos, &fbo[0]);
@@ -719,7 +726,10 @@ gst_gl_memory_copy_teximage (GstGLMemory * src, guint tex_id,
     gst_gl_query_start_log (GST_GL_BASE_MEMORY_CAST (src)->query,
         GST_CAT_GL_MEMORY, GST_LEVEL_LOG, NULL, "%s", "BlitFramebuffer took");
     gl->ReadBuffer (GL_COLOR_ATTACHMENT0);
-    gl->DrawBuffer (GL_COLOR_ATTACHMENT0);
+    if (gl->DrawBuffers)
+      gl->DrawBuffers (1, multipleRT);
+    else
+      gl->DrawBuffer (GL_COLOR_ATTACHMENT0);
     gl->BlitFramebuffer (0, 0, out_width, out_height,
         0, 0, out_width, out_height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
     gst_gl_query_end (GST_GL_BASE_MEMORY_CAST (src)->query);
@@ -729,6 +739,9 @@ gst_gl_memory_copy_teximage (GstGLMemory * src, guint tex_id,
     gl->BindFramebuffer (GL_READ_FRAMEBUFFER, 0);
 
     gl->DeleteFramebuffers (n_fbos, &fbo[0]);
+
+    if (gl->DrawBuffer)
+      gl->DrawBuffer (GL_NONE);
   }
 
   gst_memory_unmap (GST_MEMORY_CAST (src), &sinfo);