Diving into Emitter-System Overrides

In this chapter, we will explore overrides in Niagara.

Overrides are used to extend or modify the behavior of existing objects in the system without making destructive changes to the original settings of the system, as well as allowing for customizations specific to a particular implementation. We will understand how to use overrides to develop a workflow where we can reuse our emitters in multiple projects.

The override workflow is useful as it extends the functionality of an existing particle system. This modified particle system can access the inputs and outputs of the original particle system and modify its behavior as needed. It also lets us design a production workflow where we can reuse existing particle systems and tweak them as required in our Unreal projects. We can have a library of basic effects and then tweak them on a per-project basis.

After that, we will also learn about emitter and module defaults and how they help while...

Technical requirements

Unreal Engine 5.1 or above is required. The installation procedure was explained in Chapter 1.

You can find the project we worked on in this book here:

https://github.com/PacktPublishing/Build-Stunning-Real-time-VFX-with-Unreal-Engine-5

Module Override

Niagara offers a unique workflow whereby one can create a library of emitters with generic values and modules and then tweak them as per specific project requirements. This is possible because of the override functionality. Module overrides allow users to extend the behavior of existing modules by adding override modules to the emitters. These override modules are added at the Particle System level. Let us understand this with a practical example. In the previous chapters, we created an emitter, and we then called the emitter in the Niagara System.

Figure 5.1: Comparing the Overview nodes for the same emitter

Let us compare how the Overview nodes differ when they are an Emitter asset and when they are a Particle System asset. We know that the Emitter asset is referenced in the Particle System asset, and we expect the same to be the case for the Overview nodes. Let us see whether there are any differences. When you compare the Overview node of...

Parameter Override

Sometimes we need to override only particular properties of a module rather than the whole module at the System level. Niagara allows us to do that too. This helps us create a library of modules for reuse and not have to worry about the correct values for all parameters. These parameters will be tweaked in the System node by overriding the values set in the emitter. Let us now see how the override functionality works when it comes to module parameter values.

First, we will select the Emitter node and select the Curl Noise Force module. We see that for the Curl Noise Force module, we have set the value of Noise Frequency to 1.0. This is not the default value of this property. Therefore, a white arrow pointing left will be shown on the right side of the property.

Figure 5.9: White reset arrow in the Emitter node property

Clicking on that arrow will reset the value of the property to its module default of 50.0. Once the value is set to the...

Summary

In this chapter, we saw the relationship between Emitter nodes and System nodes. We saw how we can add and override modules in the System node. We also saw how specific parameters in a module can be overridden in the System node. We understood that this enables us to design a workflow where a team can develop a library of emitter modules for reuse in all their projects and tweak the values of the emitters in the System node.

In the next chapter, we will learn about Dynamic Inputs.