Fix TrigonometryBlock code generation

src/Materials/Node/Blocks/trigonometryBlock.ts

@@ -192,6 +192,12 @@ export class TrigonometryBlock extends NodeMaterialBlock {
 
         this.operation = serializationObject.operation;
     }
+
+
+    protected _dumpPropertiesCode() {
+        var codeString = `${this._codeVariableName}.operation = BABYLON.TrigonometryBlockOperations.${TrigonometryBlockOperations[this.operation]};\r\n`;
+        return codeString;
+    }    
 }
 
 _TypeStore.RegisteredTypes["BABYLON.TrigonometryBlock"] = TrigonometryBlock;