Grouping and Linking Objects
Overview
The bigger the level becomes, the more objects there will be within it, which leads to a high chance of things getting cluttered and confused. The layer system is an easy way to keep objects organized.
The grouping system is another way to control multiple objects as a single thing.
Linking allows you to create parent/child links between the objects, passing down changes through the hierarchy.
Grouping
Grouping objects is very useful for manipulating several objects as one, single entity.
To create a group, you must first select the objects that you want within the group; do this by dragging a selection box round them, or by selecting them individually.
Group
One important thing to remember about groups is that once an object is within a closed group, it cannot be independently edited; therefore, make sure that the objects have been set up beforehand.
To create a group, on the Group menu, click Group. The following dialog box will be displayed:
After the objects have been grouped, a bounding box will be displayed around the group, with a group specific pivot point.
Ungroup
This will revert all objects in the group back to their individual state.
Open
This function allows you to open a group and edit each individual object within it, without un-grouping the grouped objects.
Close
This will close a group that was previously opened.
Attach
This option allows you to add another object (including other groups) to the desired group. Select the object you wish to attach, activate the Attach function and then click the Group you want to attach it to.
There is also an Attach function inside the RollupBar which will appear when you select a group. This cannot be used to attach objects to that selected group. You can use it however to attach that group to another group.
To avoid any confusion, always remember that if you activate the Attach function, the next object you click on must be a group.
If you're having trouble selecting the group to attach it to, activate Helpers and hold Space to show pivot points, then click the pivot point of the Group.
Detach
This option removes the selected object from its group. To select an object within a group, you must first open the group. Once you have the object selected, click Detach and the object will be removed from the group.
Saving Grouped Objects
To save the group to an external file, go to the Modify section of the toolbar and select Save Object(s). To load in a previously saved group, on the same menu, select Load Object(s).
Linking
Linking an Entity object to another will create a parent-child connection between the two objects.
Note the linked objects need to be Entities and will not work on static Brush objects.
Physical changes such as position, rotation, and scale to the parent object are propagated to any child objects. This link works in one direction only; changing the child will not affect the parent.
Link
Link and Unlink can be found in the Modify menu.
These options can also be found on the main icon bar. The icon to the left is to Link, the right one is to Unlink.
To link two objects, click Link, and then click and hold down the mouse pointer on the child object. Next, move the mouse pointer to the intended parent object and release the mouse button.
Unlink
By clicking Unlink on the child object, all links and dependencies will be removed.
In the example below, we'll link the Child object (Pyramid on the left) to the Parent object (Sphere on the right).
Activate the link button, left click on the Child object, drag your mouse over to the Parent object, let go of the left mouse button.
Examples
| Red Line Represents Link In Progress | Blue Line Represents Link Completed |
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| Child object can be moved independent of Parent | Moving Parent object also moves Child |
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Entity Linking
You can create logical links by using the entity properties browser in the RollupBar. This is used to logically associate two objects to each other; for example, to connect an area shape to an area trigger.
Note that this is not a physical link and moving the parent will not move the child.
- Select the Entity and scroll down to the Entity Links section in the RollupBar.
- Then, click Pick Target and click the desired target.
A green line will indicate the link.
Right-click the link in the objects settings in the RollupBar, to edit its properties.
If you cannot see the link like in the picture above, make sure you have display links enabled in the editor preferences.
Change Target Entity
Click this option and you will be able to select a new target for the link: Tools -> Preferences -> Viewports -> General -> Viewport Displaying -> Display Object Links
Rename Link
This will allow you to give the link a new name.
Delete Link
This will permanently remove the link.
Pick New Target
This will allow you to pick additional targets for the entity. Right-clicking an empty field in the Entity Links box will also bring up this option.
Linking During Run-time by Using Flow Graph
Flow Graph will also allow you to link and unlink objects while the game is running.
The associated nodes are found in the Entity folder in Flow Graph. The two Nodes are Attach Child (to attach an entity) and Detach This (to detach an entity).