From 498264959a0ce0f036ce70b6cdc0db7d255ae32d Mon Sep 17 00:00:00 2001
From: Adam Jackson <ajax@redhat.com>
Date: Wed, 18 Dec 2019 13:50:51 -0500
Subject: [PATCH] cogl: Add support for GL_ANGLE_pack_reverse_row_order

This is the GLES equivalent of GL_MESA_pack_invert.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/980
---
 cogl/cogl/driver/gl/cogl-framebuffer-gl.c   | 13 +++++++++++--
 cogl/cogl/driver/gl/gles/cogl-driver-gles.c |  4 ++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/cogl/cogl/driver/gl/cogl-framebuffer-gl.c b/cogl/cogl/driver/gl/cogl-framebuffer-gl.c
index b956a8314..3c91c9ff8 100644
--- a/cogl/cogl/driver/gl/cogl-framebuffer-gl.c
+++ b/cogl/cogl/driver/gl/cogl-framebuffer-gl.c
@@ -106,6 +106,9 @@
 #ifndef GL_PACK_INVERT_MESA
 #define GL_PACK_INVERT_MESA 0x8758
 #endif
+#ifndef GL_PACK_REVERSE_ROW_ORDER_ANGLE
+#define GL_PACK_REVERSE_ROW_ORDER_ANGLE 0x93A4
+#endif
 #ifndef GL_BACK_LEFT
 #define GL_BACK_LEFT				0x0402
 #endif
@@ -1190,6 +1193,7 @@ _cogl_framebuffer_gl_read_pixels_into_bitmap (CoglFramebuffer *framebuffer,
   GLenum gl_intformat;
   GLenum gl_format;
   GLenum gl_type;
+  GLenum gl_pack_enum = GL_FALSE;
   gboolean pack_invert_set;
   int status = FALSE;
 
@@ -1220,7 +1224,12 @@ _cogl_framebuffer_gl_read_pixels_into_bitmap (CoglFramebuffer *framebuffer,
       (source & COGL_READ_PIXELS_NO_FLIP) == 0 &&
       !cogl_is_offscreen (framebuffer))
     {
-      GE (ctx, glPixelStorei (GL_PACK_INVERT_MESA, TRUE));
+      if (ctx->driver == COGL_DRIVER_GLES2)
+        gl_pack_enum = GL_PACK_REVERSE_ROW_ORDER_ANGLE;
+      else
+        gl_pack_enum = GL_PACK_INVERT_MESA;
+
+      GE (ctx, glPixelStorei (gl_pack_enum, TRUE));
       pack_invert_set = TRUE;
     }
   else
@@ -1414,7 +1423,7 @@ EXIT:
    * to interfere with other Cogl components so all other code can assume that
    * we leave the pack_invert state off. */
   if (pack_invert_set)
-    GE (ctx, glPixelStorei (GL_PACK_INVERT_MESA, FALSE));
+    GE (ctx, glPixelStorei (gl_pack_enum, FALSE));
 
   return status;
 }
diff --git a/cogl/cogl/driver/gl/gles/cogl-driver-gles.c b/cogl/cogl/driver/gl/gles/cogl-driver-gles.c
index a29ac49aa..fc04c8c91 100644
--- a/cogl/cogl/driver/gl/gles/cogl-driver-gles.c
+++ b/cogl/cogl/driver/gl/gles/cogl-driver-gles.c
@@ -300,6 +300,10 @@ _cogl_driver_update_features (CoglContext *context,
                                      gl_minor,
                                      gl_extensions);
 
+  if (_cogl_check_extension ("GL_ANGLE_pack_reverse_row_order", gl_extensions))
+    COGL_FLAGS_SET (private_features,
+                    COGL_PRIVATE_FEATURE_MESA_PACK_INVERT, TRUE);
+
   /* Note GLES 2 core doesn't support mipmaps for npot textures or
    * repeat modes other than CLAMP_TO_EDGE. */