From cfb0d7e9f363090f848723ba443e26d2a67c47e4 Mon Sep 17 00:00:00 2001
From: Matthew Waters <matthew@centricular.com>
Date: Mon, 26 Oct 2015 17:36:21 +1100
Subject: [PATCH] glviewconvert: expose the element on gles2 platforms

We can do everything with gles3 however gles2 restricts us not allowing
separated or frame-by-frame multiview modes due to multiple draw buffers.
---
 ext/gl/gstopengl.c                 | 10 +++++-----
 gst-libs/gst/gl/gstglviewconvert.c | 11 +++++++++++
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/ext/gl/gstopengl.c b/ext/gl/gstopengl.c
index 1fad0a239b..7784f0ae30 100644
--- a/ext/gl/gstopengl.c
+++ b/ext/gl/gstopengl.c
@@ -199,6 +199,11 @@ plugin_init (GstPlugin * plugin)
           GST_RANK_NONE, GST_TYPE_GL_FILTER_APP)) {
     return FALSE;
   }
+
+  if (!gst_element_register (plugin, "glviewconvert",
+          GST_RANK_NONE, GST_TYPE_GL_VIEW_CONVERT_ELEMENT)) {
+    return FALSE;
+  }
 #if HAVE_JPEG
 #if HAVE_PNG
   if (!gst_element_register (plugin, "gloverlay",
@@ -228,11 +233,6 @@ plugin_init (GstPlugin * plugin)
     return FALSE;
   }
 
-  if (!gst_element_register (plugin, "glviewconvert",
-          GST_RANK_NONE, GST_TYPE_GL_VIEW_CONVERT_ELEMENT)) {
-    return FALSE;
-  }
-
   if (!gst_element_register (plugin, "glmosaic",
           GST_RANK_NONE, GST_TYPE_GL_MOSAIC)) {
     return FALSE;
diff --git a/gst-libs/gst/gl/gstglviewconvert.c b/gst-libs/gst/gl/gstglviewconvert.c
index ef348f0bf6..149273a77c 100644
--- a/gst-libs/gst/gl/gstglviewconvert.c
+++ b/gst-libs/gst/gl/gstglviewconvert.c
@@ -1449,6 +1449,17 @@ _init_view_convert (GstGLViewConvert * viewconvert)
         "Cannot perform multiview conversion without OpenGL shaders");
     goto error;
   }
+
+  if (out_mode == GST_VIDEO_MULTIVIEW_MODE_SEPARATED
+      || out_mode == GST_VIDEO_MULTIVIEW_MODE_FRAME_BY_FRAME) {
+    if (!gl->DrawBuffers) {
+      GST_ERROR_OBJECT (viewconvert,
+          "Separate texture output mode requested however the current "
+          "OpenGL API does not support drawing to multiple buffers");
+      goto error;
+    }
+  }
+
   if ((in_flags & GST_VIDEO_MULTIVIEW_FLAGS_RIGHT_VIEW_FIRST) ==
       (out_flags & GST_VIDEO_MULTIVIEW_FLAGS_RIGHT_VIEW_FIRST)) {
     l_index = 0;