From 40bacd7e2ba29a1813a8fcd8070cf9ea4a9abca8 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sat, 29 Mar 2014 16:16:33 -0400
Subject: Don't load sprite shaders upon importing (2d sprite) module.

* 2d/sprite.scm (sprite-shader): Set to #f initially.
  (enable-sprites): New procedure.

* 2d/common.scm: Enable sprites.
---
 2d/sprite.scm       | 20 +++++++++++++-------
 examples/common.scm |  3 +++
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/2d/sprite.scm b/2d/sprite.scm
index 7c7b9c0..3b74fdb 100644
--- a/2d/sprite.scm
+++ b/2d/sprite.scm
@@ -41,7 +41,8 @@
   #:use-module (2d vector2)
   #:use-module (2d window)
   #:use-module (2d wrappers gl)
-  #:export (make-sprite
+  #:export (enable-sprites
+            make-sprite
             sprite?
             animated-sprite?
             sprite-drawable
@@ -63,12 +64,17 @@
 ;;; Sprites
 ;;;
 
-(define sprite-shader
-  (make-shader-program
-   (load-vertex-shader (string-append %pkgdatadir
-                                      "/shaders/sprite-vertex.glsl"))
-   (load-fragment-shader (string-append %pkgdatadir
-                                        "/shaders/sprite-fragment.glsl"))))
+(define sprite-shader #f)
+
+(define (enable-sprites)
+  (set! sprite-shader
+        (make-shader-program
+         (load-vertex-shader
+          (string-append %pkgdatadir
+                         "/shaders/sprite-vertex.glsl"))
+         (load-fragment-shader
+          (string-append %pkgdatadir
+                         "/shaders/sprite-fragment.glsl")))))
 
 ;; The <sprite> type represents a drawable object (texture,
 ;; texture-region, animation, etc.) with a given position, scale,
diff --git a/examples/common.scm b/examples/common.scm
index b9675eb..b26186a 100644
--- a/examples/common.scm
+++ b/examples/common.scm
@@ -21,9 +21,12 @@
              (2d keyboard)
              (2d repl)
              (2d signal)
+             (2d sprite)
              (2d window))
 
 (open-window)
+(enable-sprites)
+
 (add-hook! key-press-hook (lambda (key unicode)
                             (when (eq? key 'escape)
                               (quit-game))))
-- 
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