Add null check / nitialization for point cloud shading

Author: j9liu

Runtime/Cesium3DTileset.cs

@@ -617,7 +617,7 @@ public bool ignoreKhrMaterialsUnlit
         }
 
         [SerializeField]
-        private CesiumPointCloudShading _pointCloudShading;
+        private CesiumPointCloudShading _pointCloudShading = new CesiumPointCloudShading();
 
         /// <summary>
         /// The CesiumPointCloudShading attached to this tileset. If the tileset

Runtime/CesiumPointCloudRenderer.cs

@@ -131,7 +131,9 @@ private void UpdateAttenuationParameters()
                 5.0f :
                 this._tileset.maximumScreenSpaceError;
 
-            if (this._tileset.pointCloudShading.maximumAttenuation > 0.0f)
+            CesiumPointCloudShading pointCloudShading = this._tileset.pointCloudShading;
+
+            if (pointCloudShading.maximumAttenuation > 0.0f)
             {
                 maximumPointSize = this._tileset.pointCloudShading.maximumAttenuation;
             }
@@ -142,8 +144,6 @@ private void UpdateAttenuationParameters()
                 maximumPointSize *= Screen.dpi / 150;
             }
 
-            CesiumPointCloudShading pointCloudShading = this._tileset.pointCloudShading;
-
             float geometricError = this.GetGeometricError(pointCloudShading);
             geometricError *= pointCloudShading.geometricErrorScale;
 
@@ -227,7 +227,8 @@ private void DrawPointsWithAttenuation()
 
         void Update()
         {
-            if (this._tileset.pointCloudShading.attenuation)
+            CesiumPointCloudShading pointCloudShading = this._tileset.pointCloudShading;
+            if (pointCloudShading != null && pointCloudShading.attenuation)
             {
                 this.DrawPointsWithAttenuation();
                 this._meshRenderer.enabled = false;