Update viewer.js

viewer.js

@@ -496,7 +496,7 @@ export function changeColor(dr, dg, db, er, eg, eb, ei, op, boolTrans) {
         traverse(tubeEntity, node => {
             if (node.render && node.render.meshInstances) {
                 for (let mi of node.render.meshInstances) {
-                    mi.material = tubeTransparent;
+                    mi.material = matTransparent;
                 }
             }
         });