Update viewer.js

viewer.js

@@ -235,8 +235,15 @@ export async function initializeViewer(config, instanceId) {
       matSol.blendType = pc.BLEND_NORMAL;
       matSol.emissivve = new pc.Color(color_bg);
       matSol.emissiveIntensity = 1;
-
-      glbEntity.material = matSol;
+      matSol.update();
+
+      traverse(glbEntity, node => {
+            if (node.render && node.render.meshInstances) {
+                for (let mi of node.render.meshInstances) {
+                    mi.material = matSol;
+                }
+            }
+        });
     }
 
     const presentoirEntity =assets.presentoir.resource.instantiateRenderEntity();