Event Tracks are mainly used to trigger Blueprint Scripts within Sequencer's Director Blueprint. In your project, there may be cases where you instead want events from Sequencer to trigger in other Blueprints, such as the Level Blueprint. You can do this using Blueprint Interfaces and additional set-up steps in the Director Blueprint.
This document provides instructions on how to trigger Level Blueprint events from Sequencer's Event Track.
Prerequisites
- You have a basic understanding of how to create and open a Level Sequence.
- You have an understanding of how to create and use the Event Track.
- You have a basic understanding of Blueprints.
Create Blueprint Interface
First, create a Blueprint Interface. In the Content Browser, click Add (+) and select Blueprints > Blueprint Interface. Name your asset and open it.
In the Blueprint Interface Editor, give a unique name to the default Function, to help you locate it later in this guide.
The purpose of the Blueprint Interface is to provide communication between the Sequencer Director Blueprint and the Level Blueprint.
Implement the Interface in your Level
Next, open your Level Blueprint by clicking Level Blueprint in the Level Toolbar and selecting Open Level Blueprint.
Enable Class Settings, and in the Details panel click the Add dropdown menu for Inherited Interfaces. Locate and select your Blueprint Interface to add it to the Level Blueprint.
Right-click in the Event Graph and add the Event from your Blueprint Interface. The event name matches the name of the Function you named earlier in this guide. Add the Event and connect it to the Level Blueprint logic you want to trigger. Due to the arbitrary nature of Blueprints, this guide will assume your Level Blueprint logic is already created. In this example, the logic is activating a Niagara System.
Set Up Event Track
Now that the Level Blueprint side of the logic is set up, you can implement the rest of the logic in Sequencer's Event Track.
Open your Level Sequence, then create an Event Track by clicking Add Track (+) > Event Track > Trigger.
Select the Event Track and press Enter to create an Event keyframe at the Playhead. Double-click this keyframe to open the Director Blueprint and bind the keyframe to a new Event.
Implement Interface
Like you did in the Level Blueprint earlier, enable Class Settings in the Director Blueprint, and in the Details panel click the Add dropdown menu for Inherited Interfaces. Locate and select your Blueprint Interface to add it to the Level Blueprint.
Create Logic
Right-click in the Director Blueprint Graph and add the Function from your Blueprint Interface under the Call Function category. The Function name matches the name of the Function you named earlier in this guide.
Make sure you are using the Blueprint Interface Function that targets your Sequence Director BP. Other function targets will not work.
Connect the execution and target pins to the Event.
Bind Keyframe to Target
Lastly, return to the Event Track and right-click the keyframe. Under the Properties menu, set Pass Bound Object To to Target.
Connecting and binding the Target is a necessary step, despite there being no actual target. This is because when no target is specified, the Blueprint Interface system will fallback to the Level Blueprint, and then correctly link to the interface there.
Results
Once the preceding steps are finished, you can now play or simulate your level. Upon playing your sequence, the level event should trigger.
