Add default material to model

src/main.c

@@ -39,6 +39,14 @@ int main(void) {
     return TINY_EXIT_MODEL_LOAD_FAILED;
   }
 
+  PhongMaterial material = {
+      .ambient = 0.1f,
+      .diffuse = 0.8f,
+      .specular = 0.1f,
+      .shininess = 0.5f,
+  };
+  obj.material = material;
+
   load_shaders();
 
   clear_buffer(&(render.img), &bg);