From e142166c3e2d6f567ed0d4e4c414fa510271260f Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Fri, 7 May 2021 09:49:57 -0400
Subject: graphics: pbr: Extract shader code to separate files.

---
 Makefile.am                |  4 ++-
 chickadee/graphics/pbr.scm | 81 ++--------------------------------------------
 data/shaders/pbr-frag.glsl | 42 ++++++++++++++++++++++++
 data/shaders/pbr-vert.glsl | 39 ++++++++++++++++++++++
 4 files changed, 87 insertions(+), 79 deletions(-)
 create mode 100644 data/shaders/pbr-frag.glsl
 create mode 100644 data/shaders/pbr-vert.glsl

diff --git a/Makefile.am b/Makefile.am
index 72c5ab2..be1a53f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -131,7 +131,9 @@ dist_fonts_DATA =				\
 shadersdir = $(pkgdatadir)/shaders
 dist_shaders_DATA =				\
   data/shaders/path-vert.glsl			\
-  data/shaders/path-frag.glsl
+  data/shaders/path-frag.glsl			\
+  data/shaders/pbr-vert.glsl			\
+  data/shaders/pbr-frag.glsl
 
 info_TEXINFOS = doc/chickadee.texi
 doc_chickadee_TEXINFOS =			\
diff --git a/chickadee/graphics/pbr.scm b/chickadee/graphics/pbr.scm
index 01a330c..1ed3777 100644
--- a/chickadee/graphics/pbr.scm
+++ b/chickadee/graphics/pbr.scm
@@ -22,6 +22,7 @@
 ;;; Code:
 
 (define-module (chickadee graphics pbr)
+  #:use-module (chickadee config)
   #:use-module (chickadee math vector)
   #:use-module (chickadee graphics buffer)
   #:use-module (chickadee graphics color)
@@ -87,84 +88,8 @@
                      #:double-sided? #f))
 
 (define-graphics-variable pbr-shader
-  ;; TODO: Actually implement PBR.  For now it's just the minimal amount
-  ;; of code needed to render the base texture of a mesh.
-  (strings->shader
-   "
-#ifdef GLSL330
-layout (location = 0) in vec3 position;
-layout (location = 1) in vec2 texcoord0;
-layout (location = 2) in vec2 texcoord1;
-layout (location = 3) in vec4 color0;
-#elif defined(GLSL130)
-in vec3 position;
-in vec2 texcoord0;
-in vec2 texcoord1;
-in vec4 color0;
-#elif defined(GLSL120)
-attribute vec3 position;
-attribute vec2 texcoord0;
-attribute vec2 texcoord1;
-attribute vec4 color0;
-#endif
-#ifdef GLSL120
-varying vec2 fragTexcoord0;
-varying vec2 fragTexcoord1;
-varying vec4 fragColor0;
-#else
-out vec2 fragTexcoord0;
-out vec2 fragTexcoord1;
-out vec4 fragColor0;
-#endif
-uniform mat4 model;
-uniform mat4 view;
-uniform mat4 projection;
-
-void main(void) {
-  fragTexcoord0 = texcoord0;
-  fragTexcoord1 = texcoord1;
-  fragColor0 = color0;
-  gl_Position = projection * view * model * vec4(position.xyz, 1.0);
-}
-"
-   "
-#ifdef GLSL120
-attribute vec2 fragTexcoord0;
-attribute vec2 fragTexcoord1
-attribute vec4 fragColor0;
-#else
-in vec2 fragTexcoord0;
-in vec2 fragTexcoord1;
-in vec4 fragColor0;
-#endif
-#ifdef GLSL330
-out vec4 fragColor;
-#endif
-uniform bool textured0;
-uniform bool textured1;
-uniform bool vertexColored;
-uniform vec3 baseColorFactor;
-uniform sampler2D texture0;
-uniform sampler2D texture1;
-
-void main (void) {
-  vec4 finalColor = vec4(baseColorFactor, 1.0);
-  if(vertexColored) {
-    finalColor *= fragColor0;
-  }
-  if(textured0) {
-    finalColor *= texture(texture0, fragTexcoord0);
-  }
-  if(textured1) {
-    finalColor += texture(texture1, fragTexcoord1);
-  }
-#ifdef GLSL330
-  fragColor = finalColor;
-#else
-  gl_FragColor = finalColor;
-#endif
-}
-"))
+  (load-shader (scope-datadir "shaders/pbr-vert.glsl")
+               (scope-datadir "shaders/pbr-frag.glsl")))
 
 (define (shader-apply/pbr vertex-array material model-matrix view-matrix)
   (let* ((shader (graphics-variable-ref pbr-shader))
diff --git a/data/shaders/pbr-frag.glsl b/data/shaders/pbr-frag.glsl
new file mode 100644
index 0000000..813f9a9
--- /dev/null
+++ b/data/shaders/pbr-frag.glsl
@@ -0,0 +1,42 @@
+// -*- mode: c -*-
+
+#ifdef GLSL120
+attribute vec2 fragTexcoord0;
+attribute vec2 fragTexcoord1
+attribute vec4 fragColor0;
+#else
+in vec2 fragTexcoord0;
+in vec2 fragTexcoord1;
+in vec4 fragColor0;
+#endif
+
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
+
+uniform bool textured0;
+uniform bool textured1;
+uniform bool vertexColored;
+uniform vec3 baseColorFactor;
+uniform sampler2D texture0;
+uniform sampler2D texture1;
+
+void main (void) {
+  vec4 finalColor = vec4(baseColorFactor, 1.0);
+  // Vertex coloring.
+  if(vertexColored) {
+    finalColor *= fragColor0;
+  }
+  // Texture sampling.
+  if(textured0) {
+    finalColor *= texture(texture0, fragTexcoord0);
+  }
+  if(textured1) {
+    finalColor += texture(texture1, fragTexcoord1);
+  }
+#ifdef GLSL330
+  fragColor = finalColor;
+#else
+  gl_FragColor = finalColor;
+#endif
+}
diff --git a/data/shaders/pbr-vert.glsl b/data/shaders/pbr-vert.glsl
new file mode 100644
index 0000000..f622988
--- /dev/null
+++ b/data/shaders/pbr-vert.glsl
@@ -0,0 +1,39 @@
+// -*- mode: c -*-
+
+#ifdef GLSL330
+layout (location = 0) in vec3 position;
+layout (location = 1) in vec2 texcoord0;
+layout (location = 2) in vec2 texcoord1;
+layout (location = 3) in vec4 color0;
+#elif defined(GLSL130)
+in vec3 position;
+in vec2 texcoord0;
+in vec2 texcoord1;
+in vec4 color0;
+#elif defined(GLSL120)
+attribute vec3 position;
+attribute vec2 texcoord0;
+attribute vec2 texcoord1;
+attribute vec4 color0;
+#endif
+
+#ifdef GLSL120
+varying vec2 fragTexcoord0;
+varying vec2 fragTexcoord1;
+varying vec4 fragColor0;
+#else
+out vec2 fragTexcoord0;
+out vec2 fragTexcoord1;
+out vec4 fragColor0;
+#endif
+
+uniform mat4 model;
+uniform mat4 view;
+uniform mat4 projection;
+
+void main(void) {
+  fragTexcoord0 = texcoord0;
+  fragTexcoord1 = texcoord1;
+  fragColor0 = color0;
+  gl_Position = projection * view * model * vec4(position.xyz, 1.0);
+}
-- 
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