6
Visual Effects and Cascade in
Unreal Engine
6.1 INTRO DUCTION TO VISUAL EFFECTS AND PARTICLE
SYSTEMS TERMINOLOGIES
I
N Unreal Engine 4, a special engine component, ca lled the Cascade Particle Sys-
tem Editor, is responsible for producin g and simulating particle systems. At the
very basic fo rm, particles can be thought of as points in the 3D space with certain
properties that govern their intera ctions with on e another and the world surrounding
them. The Cascade Particle System Editor allows level designers to control and set
the particle system up and define all aspects of its governing rules; such as th e shape
of each particle, spawn rates, colors, lighting in te ractions, to name a few.
Before delvin g into the Cascade Particle System Editor and utilizing it to develop
amazing visual effects, we will first cover fundamental terminologies and the taxon-
omy of the particle systems in Unreal Engine 4. Understanding these terminologies
will help us get a fundamental grasp of the anatomy of pa rticle systems in Un real
Technology.
6.2 ANATOMY OF VISUAL EFFECTS
In order for impressive visual effects to work in real-time, we need to establish a sys-
tem com prising of several components. At the very basic, we need a Particle Emitter,
Particle Data Modules, Particle Material and Rendering System, and the Particles.
In this section we will get an introduction to each of the important comp onents in
Unreal Engine 4’s Particle and Visual Effects system.
6.2.1 PARTICLES
Let us first start with the particles themselves. A particle is basically a point in space
whose initial and lifetime attributes include, but are not limited to, its location, color,
geometry, etc. These attributes can be governed and controlled by a particle system.
Unreal E ngine uses such particle systems to calculate the spawning of each individ-
ual particle in the map to gene rate visual effects, such as clouds and dust, fire and
sparks, and many m ore fantastic e ffects. It is very important for level designers and
progr ammers to think about the effect they are trying to achieve in terms of each
individual particle, and the way these particles interact with the world to achieve the
best effect with the least amount of compu ta tional expenditures imposed on the CPU
or GPU to generate the effect.
301
302 Game Development and Simulation with Unreal Technology
FIGURE 6.1: Particle Systems reside in, and can be accessed from, the content browser.
6.2.2 PARTICLE SYSTEM
The Particle System is the asset that resides in the level. This is the asset that level
designers create to define the particle effect and all the rules that govern this effect.
Figure 6.1 shows a view of the content browser and a few particle systems within
it. Double-clicking on a particle system will open it in the Unreal’s Cascade Particle
System Editor.
6.2.3 EMITTER ACTOR
This is the actor, or the object that resides in the map (the scene). The Emitter Actor
holds the reference to your particle system and is respon sib le for emitting the parti-
cles that are governed under the rules of the Particle System it references. Figure 6.2
shows an emitter actor placed in the map, generating the bullet-like particles.
6.2.4 EMITTER
An Emitter is within the Cascade Particle System Editor. This term refers to the
individual effect which Cascade utilizes to define the Particle System. It is important
to note that a single visual effect may be defined by a num ber of individual emitters.
For exam ple, an explo sio n effect could be defined by several emitters within Cascade,
one for the smoke effect, one for the lighting of the explosion, one for the pieces
of shrapnel thrown ou t by the explosion and so on. Figure 6.3 shows an example
of a visua l effect particle system made of five individ ual Emitters. Each individual
Emitter controls one aspec t of the particle system.
6.2.5 MODULE
A module is the component of an emitter that c ontrols and defines a single a spect of
the emitter. For example, if we want to control the initial color of each pa rticle that is
spawned by the particle system , w e can use the Initial Color module of the emitter.

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