From 14ea7b336cb8ac0829dee207733cff7a5df7cbe8 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Fri, 5 Feb 2016 18:22:36 -0500
Subject: render: framebuffer: Add framebuffer-null?

* sly/render/framebuffer.scm (framebuffer-null?): New procedure.
---
 sly/render/framebuffer.scm | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sly/render/framebuffer.scm b/sly/render/framebuffer.scm
index c3af36a..e533f7a 100644
--- a/sly/render/framebuffer.scm
+++ b/sly/render/framebuffer.scm
@@ -31,6 +31,7 @@
   #:use-module (sly wrappers gl)
   #:export (make-framebuffer
             framebuffer?
+            framebuffer-null?
             framebuffer-id framebuffer-renderbuffer-id
             framebuffer-texture
             null-framebuffer
@@ -58,6 +59,10 @@
 (define null-framebuffer
   (%make-framebuffer 0 0 #f))
 
+(define (framebuffer-null? framebuffer)
+  "Return #t if FRAMEBUFFER is the null framebuffer."
+  (eq? null-framebuffer framebuffer))
+
 (define make-framebuffer
   (let ((draw-buffers (u32vector (version-3-0 color-attachment0))))
     (lambda (width height)
-- 
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