Particle Systems Using and Creating Copyright © 2015 Curt Hill.

Particle Systems

Using and Creating

Copyright © 2015 Curt Hill

Introduction

• Particle systems are way to add inconsequential movement and realism to a level

• There are several that come with UDK

• You may also create your own• Like SpeedTree gives you the

option to inject realism easily


A Particle

• A simplified actor that moves within a level for a limited time

• There are two pieces:– An emitter– A particle

• These typically do not interact with the players that much


The Particle

• Polygon mesh, although usually very simple

• Each particle has: – A starting position – determined by the

emitter– A lifetime – usually measured in

seconds– A characteristic trajectory

• It is spawned, it moves and then disappears


Mesh• Most actors have a complicated

mesh with suitable material covering– Typical tree is thousands of polygons

• The quad particle is most common– A single four sided polygon

• A card

– It is covered with a material

• More complicated meshes are allowed but are often not needed


Lifetime

• The emitter spawns the particles• The lifetime is the duration in

seconds in which they exist• A rain drop might exist for five

seconds• A bug may exist for considerable

longer


Distribution

• The particle never comes to rest• The distribution describes its

position and scale over time• Raindrops and bugs do not change

in their lifetime but smoke and fire might


Level Of Detail

• LOD for short• Gives the ability to have a low

quality and a high quality representation depending on distance– High requires more rendering work – Why do this when you are far away?


The Emitter

• An invisible 3D solid that spawns particles throughout its space

• A gun muzzle will be a small emitter– It appears that the muzzle flashes

come from a single point

• A rain cloud will be a large solid– The rain drops will start in a wide area


Multiple Emitters

• A particle emitter may have one or more actual emitters

• Multiples allow variations in appearance

• Rain drop splashes have four– Each of which has a different splash

pattern

• Cloud has just one


Using Particle Systems

• The UDK comes with more than a hundred particle systems

• Like any actor they are placed into the level by dragging from the content browser

• Adjust with the transformational and scaling widget


Cascade Editor

• This allows you to change the characteristics of a system

• These can be saved for future uses as well

• In the next image are four areas– 1 Preview Pane– 2 Emitter Pane– 3 Properties Pane (context dependent)– 4 Curve Editor Pane


Cascade Editor


1 2

34

Emitter Properties


Conclusion

• Lets make the rain fall


Particle Systems Using and Creating Copyright © 2015 Curt Hill.

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