[Mesa-stable] [PATCH] mesa: Accept GL_BACK in get_fb0_attachment with ARB_ES3_1_compatibility.

[Kenneth Graunke]

According to the ARB_ES3_1_compatibility specification,
glGetFramebufferAttachmentParameteriv is supposed to accept BACK,
and it behaves exactly like BACK_LEFT.

Fixes a GL error in GFXBench 5 Aztec Ruins.

Cc: mesa-stable at lists.freedesktop.org
---
 src/mesa/main/fbobject.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
index 71e91f9301f..9a2c7ebbcf7 100644
--- a/src/mesa/main/fbobject.c
+++ b/src/mesa/main/fbobject.c
@@ -330,6 +330,15 @@ get_fb0_attachment(struct gl_context *ctx, struct gl_framebuffer *fb,
       return &fb->Attachment[BUFFER_BACK_LEFT];
    case GL_BACK_RIGHT:
       return &fb->Attachment[BUFFER_BACK_RIGHT];
+   case GL_BACK:
+      /* The ARB_ES3_1_compatibility spec says:
+       *
+       *    "Since this command can only query a single framebuffer
+       *     attachment, BACK is equivalent to BACK_LEFT."
+       */
+      if (ctx->Extensions.ARB_ES3_1_compatibility)
+         return &fb->Attachment[BUFFER_BACK_LEFT];
+      return NULL;
    case GL_AUX0:
       if (fb->Visual.numAuxBuffers == 1) {
          return &fb->Attachment[BUFFER_AUX0];
-- 
2.14.2