Phong lighting, flat shader

shaders/flat.frag

@@ -2,6 +2,7 @@
 
 in vec3 UV;
 in vec3 NORMAL;
+in vec3 LIGHT;
 
 out vec4 FragColor;
 
@@ -14,16 +15,7 @@ struct Material {
   bool unshaded;
 };
 
-struct DirectionalLight {
-  vec3 direction;
-  vec3 color;
-  float ambient;
-  float diffuse;
-  float specular;
-};
-
 uniform Material material;
-uniform DirectionalLight directionalLight;
 
 void main() {
   FragColor = vec4(0.0);
@@ -38,12 +30,6 @@ void main() {
   }
 
   if (!material.unshaded) {
-    vec3 ambient = directionalLight.ambient * directionalLight.color;
-    ambient = max(ambient, 0.0);
-    
-    vec3 diffuse = directionalLight.diffuse * dot(directionalLight.direction, NORMAL) * directionalLight.color;
-    diffuse = max(diffuse, 0.0);
-    
-    FragColor *= vec4(ambient + diffuse, 1.0);
+    FragColor *= vec4(LIGHT, 1.0);
   }
 }

shaders/flat.vert

@@ -10,10 +10,39 @@ uniform mat4 PROJECTION;
 
 out vec3 UV;
 out vec3 NORMAL;
+out vec3 LIGHT;
+
+struct DirectionalLight {
+  vec3 direction;
+  vec3 color;
+  float ambient;
+  float diffuse;
+  float specular;
+};
+
+uniform DirectionalLight directionalLight;
 
 void main() {
   vec4 vertex = PROJECTION * VIEW * MODEL * vec4(pos, 1.0);
   gl_Position = vertex;
   UV = vec3(uv * vertex.z, vertex.z);
-  NORMAL = (PROJECTION * VIEW * MODEL * vec4(normal, 0.0)).xyz;
+
+  NORMAL = (VIEW * MODEL * vec4(normal, 0.0)).xyz;
+
+  // Flat shading, we compute light per vertex
+  vec3 ambient = directionalLight.ambient * directionalLight.color;
+
+  vec3 direction = -(VIEW * vec4(directionalLight.direction, 0.0)).xyz;
+  float diff = dot(normalize(direction), normalize(NORMAL));
+  diff = max(diff, 0.0);
+  vec3 diffuse = directionalLight.diffuse * diff * directionalLight.color;
+
+  vec3 viewDir = (VIEW * MODEL * vec4(pos, 1.0)).xyz;
+  vec3 reflectionDir = reflect(normalize(direction), normalize(NORMAL));
+  float spec = dot(viewDir, reflectionDir);
+  spec = max(spec, 0.0);
+  spec = pow(spec, 2);
+  vec3 specular = directionalLight.specular * spec * directionalLight.color;
+
+  LIGHT = ambient + diffuse + specular;
 }