Very briefly, the following paragraph (taken from the official Unreal 4 documentation that's available online) very aptly describes the relationship between the different components that are used in particle systems:
"Modules, which define particle behavior and are placed within...Emitters, which are used to emit a specific type of particle for an effect, and any number of which can be placed within a...Particle System, which is an asset available in the Content Browser, and which can then in turn be referenced by an...Emitter Actor, which is a placeable object that exists within your level, controlling where and how the particles are used in your scene.",
Read this several times to make sure that you are clear on the relationship between the different components.
So, as described in the earlier section where we looked at P_Fire, we know that the emitters are labelled as Flames, Embers, Sparks, Smoke, and so on. The different properties of each of the emitters are defined by adding modules, such as Lifetime, Initial Velocity, and so on, into them. Together, all the emitters make up a particle system. Lastly, when you place the emitters in your game level, you are, in fact, dragging the emitter actor, which references a particular particle system.
The Default Required and Spawn modules are the modules that every emitter needs to have. There is also a long list of other optional modules that the Cascade Particle editor offers to customize your particle system. In the current version of the editor that I am using, I have the Acceleration, Attractor, Beam, Camera, Collision, Color, Event, Kill, Lifetime, Location, Orbit, Orientation, Parameter, Rotation, Rotation Rate, Size, Spawn, SubUV, Vector Field, and Velocity modules.
We will cover a few of the frequently used modules from this long list of modules through a simple exercise that's based on P_Fire. I understand that it would be very boring and not very useful when grasping the basics here if I simply gave you all those definitions that you can find easily online. Instead, we will go through this section by customizing P_Fire to create a fireplace for our level. At the same time, we will go through the key values within the different modules that you can adjust. Thus, you can take a look at how these values impact the look of the particle system.
For more detailed documentation on the definition of each module and parameter, you can refer to the Unreal 4 online documentation (https://docs.unrealengine.com/latest/INT/Engine/Rendering/ParticleSystems/Reference/index.html).
The commonly used modules are listed as follows:
|
Module |
Key parameters it can control |
|---|---|
|
Required |
Material used for the particles |
|
Spawn |
Rate and distribution of the spawn |
|
Initial Size |
Size of the initial particle |
|
Lifetime |
Time duration for which the particle stays visible |
|
Color Over Life |
Color of the particles over their lifetimes |