model loading, load material from model, changed some architecture.

src/main/java/DirectionalLight.java

@@ -2,15 +2,19 @@ import org.joml.Vector3f;
 
 public class DirectionalLight {
     public Vector3f direction;
-    public Vector3f color;
-    public float intensity;
+
+    public Vector3f ambient;
+    public Vector3f diffuse;
+    public Vector3f specular;
 
     public DirectionalLight (
             Vector3f direction,
-            Vector3f color,
-            float intensity) {
+            Vector3f ambient,
+            Vector3f diffuse,
+            Vector3f specular) {
         this.direction = direction;
-        this.color = color;
-        this.intensity = intensity;
+        this.ambient = ambient;
+        this.diffuse = diffuse;
+        this.specular = specular;
     }
 }