Add OpenGL shading language (GLSL)

This is the language used for writing OpenGL shaders, which are becoming much more mainstream lately.

samples/GLSL/shader.fp

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2010 Josh A. Beam
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+const int NUM_LIGHTS = 3;
+const vec3 AMBIENT = vec3(0.1, 0.1, 0.1);
+const float MAX_DIST = 2.5;
+const float MAX_DIST_SQUARED = MAX_DIST * MAX_DIST;
+
+uniform vec3 lightColor[NUM_LIGHTS];
+
+varying vec3 fragmentNormal;
+varying vec3 cameraVector;
+varying vec3 lightVector[NUM_LIGHTS];
+
+void
+main()
+{
+	// initialize diffuse/specular lighting
+	vec3 diffuse = vec3(0.0, 0.0, 0.0);
+	vec3 specular = vec3(0.0, 0.0, 0.0);
+
+	// normalize the fragment normal and camera direction
+	vec3 normal = normalize(fragmentNormal);
+	vec3 cameraDir = normalize(cameraVector);
+
+	// loop through each light
+	for(int i = 0; i < NUM_LIGHTS; ++i) {
+		// calculate distance between 0.0 and 1.0
+		float dist = min(dot(lightVector[i], lightVector[i]), MAX_DIST_SQUARED) / MAX_DIST_SQUARED;
+		float distFactor = 1.0 - dist;
+
+		// diffuse
+		vec3 lightDir = normalize(lightVector[i]);
+		float diffuseDot = dot(normal, lightDir);
+		diffuse += lightColor[i] * clamp(diffuseDot, 0.0, 1.0) * distFactor;
+
+		// specular
+		vec3 halfAngle = normalize(cameraDir + lightDir);
+		vec3 specularColor = min(lightColor[i] + 0.5, 1.0);
+		float specularDot = dot(normal, halfAngle);
+		specular += specularColor * pow(clamp(specularDot, 0.0, 1.0), 16.0) * distFactor;
+	}
+
+	vec4 sample = vec4(1.0, 1.0, 1.0, 1.0);
+	gl_FragColor = vec4(clamp(sample.rgb * (diffuse + AMBIENT) + specular, 0.0, 1.0), sample.a);
+}