From feb3c58215960f2bac66922e8d1a1f8e32b7ff95 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Fri, 7 May 2021 09:53:23 -0400
Subject: graphics: phong: Extract shader code to separate files.

---
 data/shaders/phong-frag.glsl | 89 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 data/shaders/phong-frag.glsl

(limited to 'data/shaders/phong-frag.glsl')

diff --git a/data/shaders/phong-frag.glsl b/data/shaders/phong-frag.glsl
new file mode 100644
index 0000000..ad324b3
--- /dev/null
+++ b/data/shaders/phong-frag.glsl
@@ -0,0 +1,89 @@
+// -*- mode: c -*-
+
+struct Material {
+  vec3 ambient;
+  sampler2D ambientMap;
+  bool useAmbientMap;
+  vec3 diffuse;
+  sampler2D diffuseMap;
+  bool useDiffuseMap;
+  vec3 specular;
+  sampler2D specularMap;
+  bool useSpecularMap;
+  float shininess;
+  sampler2D bumpMap;
+  bool useBumpMap;
+};
+
+struct DirectionalLight {
+  vec3 direction;
+  vec3 ambient;
+  vec3 diffuse;
+  vec3 specular;
+};
+
+#ifdef GLSL120
+varying vec3 fragNorm;
+varying vec2 fragTex;
+#else
+in vec3 fragNorm;
+in vec2 fragTex;
+#endif
+
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
+
+uniform Material material;
+uniform DirectionalLight directionalLight;
+
+void main() {
+  vec3 baseAmbientColor;
+  vec3 baseDiffuseColor;
+  vec3 baseSpecularColor;
+  if(material.useAmbientMap) {
+#ifdef GLSL330
+    baseAmbientColor = texture(material.ambientMap, fragTex).xyz;
+#else
+    baseAmbientColor = texture2D(material.ambientMap, fragTex).xyz;
+#endif
+  } else {
+    baseAmbientColor = vec3(1.0, 1.0, 1.0);
+  }
+  if(material.useDiffuseMap) {
+    // discard transparent fragments.
+#ifdef GLSL330
+    vec4 color = texture(material.diffuseMap, fragTex);
+#else
+    vec4 color = texture2D(material.diffuseMap, fragTex);
+#endif
+    if(color.a == 0.0) { discard; }
+    baseDiffuseColor = color.xyz;
+  } else {
+    baseDiffuseColor = vec3(1.0, 1.0, 1.0);
+  }
+  if(material.useSpecularMap) {
+#ifdef GLSL330
+    baseSpecularColor = texture(material.specularMap, fragTex).xyz;
+#else
+    baseSpecularColor = texture2D(material.specularMap, fragTex).xyz;
+#endif
+  } else {
+    baseSpecularColor = vec3(1.0, 1.0, 1.0);
+  }
+  vec3 ambientColor = material.ambient * baseAmbientColor * baseDiffuseColor;
+  vec3 lightDir = normalize(-directionalLight.direction);
+  float diffuseFactor = max(dot(lightDir, fragNorm), 0.0);
+  vec3 diffuseColor = diffuseFactor * baseDiffuseColor * material.diffuse;
+  vec3 reflectDir = reflect(-lightDir, fragNorm);
+  float specularFactor = 0;
+  if(material.shininess > 0) {
+    specularFactor = pow(max(dot(lightDir, reflectDir), 0.0), material.shininess);
+  }
+  vec3 specularColor = specularFactor * baseSpecularColor * material.specular;
+#ifdef GLSL330
+  fragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
+#else
+  gl_FragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
+#endif
+}
-- 
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