[LayaAirIDE 2.0]PBR标准材质实时阴影渲染问题

先上unity和laya效果的对比图

import ModelViewer from "./ModelViewer";

import Scene = Laya.Scene;

export default class Game3D extends Scene {

	constructor() {

		super();

		//初始化引擎

		Laya3D.init(0, 0);

		var scene_360 = Laya.loader.getRes("LayaScene_PUCHENG3D/Conventional/PUCHENG3D.ls") as Laya.Scene3D;

		Laya.stage.addChildAt(scene_360, 0);

		var camera = (scene_360 as Laya.Node).getChildByName('Main Camera') as Laya.Camera;

		// var camera = new Laya.Camera(0, 0.1, 100);

		// scene_360.addChild(camera);

		camera.transform.rotationEuler = new Laya.Vector3(-32, -75, 0);

		camera.transform.position = new Laya.Vector3(-8.2, 5.3, 2.2);

		var modelViewer = camera.addComponent(ModelViewer);

		modelViewer.AroundPos = Laya.Vector3._ZERO;

		

		var directionLight = (scene_360 as Laya.Node).getChildByName('Directional light') as Laya.DirectionLight;

		//灯光开启阴影

		directionLight.shadow = true;

		//可见阴影距离

		directionLight.shadowDistance = 20;

		directionLight.shadowResolution = 2048;

		var receiveShadowgroup = (scene_360 as Laya.Node).getChildByName('PuCheng').getChildByName('receiveShadow');

		var castShadowgroup = (scene_360 as Laya.Node).getChildByName('PuCheng').getChildByName('castShadow');

		receiveShadowgroup._children.forEach(_model => {

			//(_model as Laya.MeshSprite3D).meshRenderer.castShadow = true;

			(_model as Laya.MeshSprite3D).meshRenderer.receiveShadow = true;

		});

		castShadowgroup._children.forEach(_model => {

			(_model as Laya.MeshSprite3D).meshRenderer.castShadow = true;

			//(_model as Laya.MeshSprite3D).meshRenderer.receiveShadow = true;

		});

	}

}

以上代码是对灯光阴影的设置，和模型网格光照信息设置。（好坑，unity设置的接收阴影产生阴影都不管用，得重新代码撸！！）
 
模型用的材质是'PBR(Standard)'，求大佬和技术人员解惑，看看我这是啥地方出了问题。