Chapter 10.0 FX Authoring

FX artists are tasked with recreating real-world, imaginary, and other dramatic effects for use within games. Weapon projectiles and the trail effects from them, explosions, effects from magic spells, sword trails, etc. are all effects that would fall under the purvey of the FX artist. These effects are generally created using particles and materials. The FX artist must have a solid grasp of particle systems and the material system and how to combine them to achieve the desired results to bring the world to life.

Cascade User Guide
Cascade is a tool for creating particle-based effects using emitters in the Unreal Engine. 

Particle System Reference 
Particle effects such as fire, explosions, energy beams, etc. in Unreal Engine 3 are produced through the creation and use of Particle Systems. 
A Particle System is a content asset that consists of any number of emitters. Each emitter can have a single TypeData module which determines the type of particles the emitter emits: Sprite, beam, Ribbon, Mesh, PhysX, etc. In addition to the TypeData module, each emitter contains any number of modules that effect how its particles behave, such as Location, Velocity, Size, Color, etc.

Particle systems are created through the Content Browser and constructed using Cascade, the particle editor. This document will explain particle systems, emitters, and each module available.

Distributions are a group of data types that provide flexibility by allowing for constant values, random values within a range, values interpolated along a curve, and values driven by parameters. These are generally used in properties of Particle Systems and nodes within SoundCues. 

Lens Flare Editor User Guide 
The Lens Flare system has been recently introduced. The lens flare editor is a tweaked version of Cascade, where you add sprites as elements that each reference a material. 

VFX Optimization
This document assumes prior knowledge of Cascade, the Material Editor, Kismet, and Matinee along with common effects related performance issues. There are multiple avenues to a performance issue solution, this document attempts to outline how Epic's effects team goes about solving these issues with the tools available in UE3. 
Particle Examples 
This page is intended to be a quick-reference document for implementing different types of particle effects using materials and the Particle Editor in UnrealEd. For a comprehensive reference, see the Particles and Emitters Reference page; and for working with particles, see the Cascade User Guide.

Particles SubUV Tutorial 
The Unreal Engine's Particle System provides an emitter TypeDataModule that allows for the selection of sub-images from a source texture to be displayed on its particles. It works by allowing you to select the sub-image to display for a particular particle as a function of the lifetime of the particle. See the CascadeUserGuide for a general description of the Cascade Particle Editor.
(This document assumes you are familiar with the Content Browser, and with creating packages and objects within those packages.)

Fake Mesh Lighting 
This doc covers fake lighting on mesh (or mesh particles).

Anim Trails 
AnimTrails allow for displaying a trail or streak behind an animation using data sampled directly from the animation itself. By sampling at a user-set framerate, they provide a framerate-independent way to generate effects such as weapon trails.
(This document assumes you are familiar with the basics of Cascade, the Content Browser, and with creating packages and objects within those packages.)

Per Actor Particle Collision
It is now possible to setup Actor specific collisions for instances of effects. This feature is typically used when an effect requires collision, and the effect is called via Kismet, Matinee, or a Script from a fixed world position which does not change. (Scripted Event) In essence the emitter location, orientation etc. will be the same every time as in the case of a matinee toggled effect.

By specifying Actors for an effect to collide with we can reduce GameThread overhead consumed by calculations related to particle collision. Any emitters with the Collision Actor Module on them in the particle system, will only collide with the actors specified in the Emitter Actor; subsequently flying or falling through everything else.

It can be helpful to understand Particle Parameters prior to setting up per actor collisions. Please refer to the Collision Module for more information on setting collision behavior.

Using Instance Parameters
Instance Parameters are a very powerful part of the effects pipeline in UE3. Particle Paramters can be used to control a multitude of values, on a per instance basis. Particle Parameters are often used on placed level effects, though they can also be called by game code to control various modules.

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