1 files changed, 134 insertions, 40 deletions

diff --git a/data/shaders/phong-frag.glsl b/data/shaders/phong-frag.glsl
index ad324b3..84e9feb 100644
--- a/data/shaders/phong-frag.glsl
+++ b/data/shaders/phong-frag.glsl
@@ -15,17 +15,23 @@ struct Material {
   bool useBumpMap;
 };
 
-struct DirectionalLight {
+struct Light {
+  bool enabled;
+  int type;
+  vec3 position;
   vec3 direction;
-  vec3 ambient;
-  vec3 diffuse;
-  vec3 specular;
+  vec4 color;
+  float cutOff;
 };
 
+#define MAX_LIGHTS 4
+
 #ifdef GLSL120
+varying vec3 fragWorldPos;
 varying vec3 fragNorm;
 varying vec2 fragTex;
 #else
+in vec3 fragWorldPos;
 in vec3 fragNorm;
 in vec2 fragTex;
 #endif
@@ -35,55 +41,143 @@ out vec4 fragColor;
 #endif
 
 uniform Material material;
-uniform DirectionalLight directionalLight;
+uniform Light lights[MAX_LIGHTS];
+uniform vec3 cameraPosition;
+uniform vec4 ambientLightColor;
 
-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;
+const float GAMMA = 2.2;
+
+#ifndef GLSL330
+// Compatibility shim for older GLSL versions.
+vec2 texture(sampler2D tex, vec2 coord) {
+  return texture2D(tex, coord);
+}
 #endif
+
+float posDot(vec3 v1, vec3 v2) {
+  return max(dot(v1, v2), 0.0);
+}
+
+vec3 gammaCorrect(vec3 color) {
+  return pow(color, vec3(1.0 / GAMMA));
+}
+
+vec3 toneMap(vec3 color) {
+  return color / (color + vec3(1.0));
+}
+
+vec3 lightDirection(Light light) {
+  if(light.type == 0 || light.type == 2) { // point and spot lights
+    return normalize(light.position - fragWorldPos);
+  } else if(light.type == 1) { // directional light
+    return normalize(-light.direction);
+  }
+
+  return vec3(0.0); // should never be reached.
+}
+
+vec3 lightAttenuate(Light light) {
+  float distance = length(light.position - fragWorldPos);
+  float attenuation = 1.0 / (distance * distance);
+  return light.color.rgb * attenuation;
+}
+
+vec3 lightRadiance(Light light, vec3 direction) {
+  if(light.type == 0) { // point light
+    return lightAttenuate(light);
+  } else if(light.type == 1) { // directional light
+    return light.color.rgb;
+  } else if(light.type == 2) { // spot light
+    float theta = dot(direction, normalize(-light.direction));
+    // Spot lights only shine light in a specific conical area.
+    // They have no effect outside of that area.
+    if(theta > light.cutOff) {
+      // Feather out the light as it approaches the edge of its cone.
+      float intensity = (theta - light.cutOff) / (1.0 - light.cutOff);
+      return lightAttenuate(light) * intensity;
+    } else {
+      return vec3(0.0);
+    }
+  }
+
+  return vec3(0.0); // should never be reached.
+}
+
+vec3 materialAmbient() {
+  if(material.useAmbientMap) {
+    return texture(material.ambientMap, fragTex).rgb * material.ambient;
   } else {
-    baseAmbientColor = vec3(1.0, 1.0, 1.0);
+    return material.ambient;
   }
+}
+
+vec3 materialDiffuse() {
   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;
+    // discard transparent fragments.
+    if(color.a == 0.0) {
+      discard;
+    }
+    return color.rgb * material.diffuse;
   } else {
-    baseDiffuseColor = vec3(1.0, 1.0, 1.0);
+    return material.diffuse;
   }
+}
+
+vec3 materialSpecular() {
   if(material.useSpecularMap) {
-#ifdef GLSL330
-    baseSpecularColor = texture(material.specularMap, fragTex).xyz;
-#else
-    baseSpecularColor = texture2D(material.specularMap, fragTex).xyz;
-#endif
+    return texture(material.specularMap, fragTex).rgb * material.specular;
   } else {
-    baseSpecularColor = vec3(1.0, 1.0, 1.0);
+    return material.specular;
   }
-  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 materialNormal() {
+  if(material.useBumpMap) {
+    return normalize(texture(material.bumpMap, fragTex).xyz * 2.0 - 1.0);
+  } else {
+    return fragNorm;
   }
-  vec3 specularColor = specularFactor * baseSpecularColor * material.specular;
+}
+
+void main() {
+  vec3 ambientOcclusion = materialAmbient();
+  vec3 baseDiffuseColor = materialDiffuse();
+  vec3 baseSpecularColor = materialSpecular();
+  vec3 normal = materialNormal();
+  vec3 color = vec3(0.0);
+
+  // Apply direct lighting.
+  for(int i = 0; i < MAX_LIGHTS; ++i) {
+    Light light = lights[i];
+
+    if(!light.enabled) {
+      continue;
+    }
+
+    vec3 lightDir = lightDirection(light);
+    vec3 radiance = lightRadiance(light, lightDir);
+    float diffuseFactor = posDot(lightDir, normal);
+    vec3 reflectDir = reflect(-lightDir, normal);
+    vec3 diffuseColor = baseDiffuseColor * diffuseFactor;
+    float specularFactor = 0;
+    if(material.shininess > 0) {
+      specularFactor = pow(posDot(lightDir, reflectDir), material.shininess);
+    }
+    vec3 specularColor = baseSpecularColor * specularFactor;
+    color += (diffuseColor + specularColor) * radiance;
+  }
+
+  // Apply ambient lighting.
+  vec3 ambientColor = baseDiffuseColor * ambientOcclusion * ambientLightColor.rgb;
+  color += ambientColor;
+
+  // Apply gamma correction and HDR tone mapping to get the final
+  // color.
+  vec4 finalColor = vec4(toneMap(gammaCorrect(color)), 1.0);
 #ifdef GLSL330
-  fragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
+  fragColor = finalColor;
 #else
-  gl_FragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
+  gl_FragColor = finalColor;
 #endif
 }