Test implementation of phong shader

src/main.c

@@ -41,9 +41,9 @@ int main(void) {
 
   PhongMaterial material = {
       .ambient = 0.1f,
-      .diffuse = 0.8f,
+      .diffuse = 1.2f,
       .specular = 0.1f,
-      .shininess = 0.5f,
+      .shininess = 0.8f,
   };
   obj.material = material;