From 5ff661f1e191ce486000b727d6c979779e24efe8 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sun, 4 Oct 2020 13:00:20 -0400
Subject: graphics: framebuffer: Use a fully transparent clear color.

Without this it is impossible to render multiple framebuffers on top
of each other and get the desired result.
---
 chickadee/graphics/framebuffer.scm | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/chickadee/graphics/framebuffer.scm b/chickadee/graphics/framebuffer.scm
index 967c115..091ab3f 100644
--- a/chickadee/graphics/framebuffer.scm
+++ b/chickadee/graphics/framebuffer.scm
@@ -29,6 +29,7 @@
   #:use-module (gl)
   #:use-module (gl enums)
   #:use-module (chickadee math matrix)
+  #:use-module (chickadee graphics color)
   #:use-module (chickadee graphics gl)
   #:use-module (chickadee graphics gpu)
   #:use-module ((chickadee graphics texture) #:select (make-texture null-texture))
@@ -84,6 +85,8 @@
   (gl-bind-framebuffer (version-3-0 framebuffer)
                        (framebuffer-id framebuffer)))
 
+(define %clear-color (transparency 0.0))
+
 (define make-framebuffer
   (let ((draw-buffers (u32vector (version-3-0 color-attachment0))))
     (lambda* (width height #:key (min-filter 'linear) (mag-filter 'linear)
@@ -103,7 +106,7 @@ dimensions WIDTH x HEIGHT."
              ;; rendering engine can set it whenever it changes to
              ;; this framebuffer, saving users the trouble of having
              ;; to this tedious task themselves.
-             (viewport (make-viewport 0 0 width height))
+             (viewport (make-viewport 0 0 width height #:clear-color %clear-color))
              (projection (orthographic-projection 0 width height 0 0 1))
              (framebuffer (%make-framebuffer framebuffer-id
                                              renderbuffer-id
-- 
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