Add shader module.

* 2d/shader.scm: New module.
* Makefile.am: Add 2d/shader.scm to SOURCES.
* examples/shader.scm: New example.
* examples/shaders/fragment-shader.glsl: New shader.
* examples/shaders/vertex-shader.glsl: New shader.

3 files changed, 53 insertions, 0 deletions

diff --git a/examples/shader.scm b/examples/shader.scm
new file mode 100644
index 0000000..49893ad
--- /dev/null
+++ b/examples/shader.scm
@@ -0,0 +1,33 @@
+(use-modules (2d game)
+             (2d shader)
+             (2d sprite)
+             (2d vector2)
+             (2d window))
+
+(load "common.scm")
+
+(define vertex-shader
+  (load-vertex-shader "shaders/vertex-shader.glsl"))
+(define fragment-shader
+  (load-fragment-shader "shaders/fragment-shader.glsl"))
+(define program (make-shader-program vertex-shader fragment-shader))
+
+(define window-width 800)
+(define window-height 600)
+(define sprite
+  (load-sprite "images/p1_front.png"
+               #:position (vector2 (/ window-width 2)
+                                   (/ window-height 2))))
+
+(define (draw dt alpha)
+  (with-shader-program program
+    ;; Shake the sprite around a bit.
+    (uniforms ((angle (/ (random:uniform) 100)))
+      (draw-sprite sprite))))
+
+(add-hook! draw-hook draw)
+
+(with-window (make-window #:title "Shaders"
+                          #:resolution (vector2 window-width
+                                                window-height))
+  (run-game-loop))
diff --git a/examples/shaders/fragment-shader.glsl b/examples/shaders/fragment-shader.glsl
new file mode 100644
index 0000000..9be52f0
--- /dev/null
+++ b/examples/shaders/fragment-shader.glsl
@@ -0,0 +1,7 @@
+#version 120
+
+uniform sampler2D color_texture;
+
+void main (void) {
+    gl_FragColor = texture2D(color_texture, gl_TexCoord[0].st);
+}
diff --git a/examples/shaders/vertex-shader.glsl b/examples/shaders/vertex-shader.glsl
new file mode 100644
index 0000000..2a7a4a4
--- /dev/null
+++ b/examples/shaders/vertex-shader.glsl
@@ -0,0 +1,13 @@
+#version 120
+
+uniform float angle;
+
+void main(void) {
+    mat4 RotationMatrix = mat4(cos(angle), -sin(angle), 0.0, 0.0,
+                               sin(angle), cos(angle),  0.0, 0.0,
+                               0.0,        0.0,         1.0, 0.0,
+                               0.0,        0.0,         0.0, 1.0);
+
+    gl_Position =  gl_ModelViewProjectionMatrix * RotationMatrix * gl_Vertex;
+    gl_TexCoord[0] = gl_MultiTexCoord0;
+}