**Tip:** [Candera](http://dev.doc.cgistudio.at/APILINK/namespace_candera.html "[DataBinding_RefTypeSample]") Logging is also very useful to test individual parts of your code like if-cases or loops via:
``` Candera.LogInfo(message) ``` # Id Handling This chapter explains how to get access to other nodes via the id of their attached script. Therefore, create a new Scene Composer solution using the "3D Getting started" template, which includes a 3D model of a car. To start it's important to know that there are two functions that are fundamental to get access to other nodes:
**Tip:** Also check the Sample Solution for further information and scripts.
# Communication between Children #### How to find siblings This chapter explains how to get access to sibling nodes via the id of their attached script. Because there is yet no direct way to get the ids of sibling nodes you have to use a workaround. The recommended way is to use a script on a root node which tells its child nodes the ids or even the scripts of their siblings. The diagram beneath shows the car node in the center. Its script "CarRootController" finds the door scripts of its childnodes and pass them in form of an array to the scripts of its child nodes. Now each door node has access to the other door nodes.
**Tip:** Don't forget to add the new function to the public table! (see next step)
Next we need a public boolean which tells the script that the door should get opened. Afterwards this public value 'openDoor' will get modified by another door script. ``` return { Init = Init, Update = Update, GetName = GetName, openDoor = false, } ``` Now switch to the **Update-Function** to add following lines of code: ``` local function Update(self, id) if self.openDoor == true then -- get the current x- and z-rotation of the door and change the y-rotation to a proper value local pitch, yaw, roll = Candera.GetRotation(id) Candera.SetRotation(id, pitch, yaw, -30) -- now iterate over the array with the other door scripts stored in the public variable doorScripts --and change their openDoor boolean to true so they can get opened for i, otherDoorScript in ipairs(self.doorScripts) do otherDoorScript.openDoor = true end end end ``` However yet the public array doorScripts will be nil as a root node has to find all door scripts and save them to the public array of each script. Therefore add a new array called doorScripts to the public table... ``` return { Init = Init, Update = Update, GetName = GetName, openDoor = false, doorScripts ={} } ```Lua uses 'nil' as a kind non-value, to represent the absence of a useful value.
#### Root Script ... and switch to the CarRootController script to the **Init-Function** . To find the door scripts iterate over the array childIds, get the script of each id and store it to a array. Therefore add a local array called "doorScripts" to your CarRootController script. When all the door scripts are found iterate over the doorScripts array and store the local array of door scripts to the doorScripts array of each script: ``` for i, childId in ipairs(childIds) do local script = Candera.IdToScriptComponent[childId] if script and script.GetName() == "door" then table.insert(doorScripts, script) end end for i, doorScript in ipairs(doorScripts) do doorScript.doorScripts = doorScripts end ```Don't forget to set the openDoor value in the properties panel to true at least for one door script to test if the other doors will get opened.
**Tip:** don't forget to add the callback functions **OnDisable()** and **OnEnable()** to the public table so they can get called by [Candera](http://dev.doc.cgistudio.at/APILINK/namespace_candera.html "[DataBinding_RefTypeSample]").
If you start the execution of the script system and disable the CarRootController script during runtime also the wheels should stop rotating. Furthermore if you enable the CarRootController again, the wheels start rotating and the steering lock switches. # Set Priority of Lua-Scripts #### Script Priority Another useful feature of Lua-Scripting is the priority. It defines in which order the scripts get called (f.e. the Update or the Init). To test this feature in its simplest way create four cubes and equip them with the same script called "SimpleLogInfo". ``` local function Init(self, id) Candera.LogInfo(self.logString) end return { Init = Init, logString = "logString" } ``` This script allows to enter an output string in the public table which will get written in the CanderaLogging panel. Now apply the script to each of the cubes and enter a proper log info to the public value "logString" in the Properties panel. The next step is to assign a priority value to each instance of the script:
**Tip:** for ordering script execution you can also use call-back functions. F.e. LateUpdate(self, id) is called every render frame after all Update callbacks.