| Home Page | Recent Changes | Preferences

# Collision

Collision is all about the unreal engine deciding when one actor is touching another, and what to do about it if it is. OCD gives technical lowdown of object collision detection.

Collision properties are under Actor/Collision

The difference between Blocking and Colliding is that Colliding actors only get a Touch() event when another object collides with it; Blocking actors also prevent the other object from moving to that location. Actors can be made to do none, either, or both.

If an actor with bCollideActors = true is spawned on top of another actor with bCollideActors = true, Touch() will be called before PostBeginPlay(), and possibly before the other initialization functions as well. This can cause a lot of problems, especially if initialization code important to the actor's function is initialized in PostBeginPlay() to be used later in Touch().

## related topics

- collision cylinder
- [collision box (UT)]? - I'm sure this can be done in UT. How? - Legal

Wormbo: Only Brushes (i.e. movers or BSP) can have non-cylindric collision in UT.

Legal: Yes, but as I've seen cubic locationID's in UT I think it should be quite possible, no?

Tarquin: locationID doesn't use a cylinder – AFAIK it's spherical

Legal: Yes BUT AS I'VE SEEN CUBIC ones (in Thievery UT, just 3-6 lines of code) I think I should be able to have cubic coll as well, no?

Mychaeel: Creating a LocationID variant with a cubic volume is almost trivial, but that has nothing to do with collision. The latter is entirely an engine concept.

Legal: No easy hack or bypass then?

The Unreal Engine Documentation Site

Wiki Community

Topic Categories

Image Uploads

Random Page

Recent Changes

Offline Wiki

Unreal Engine

Console Commands

Terminology

Mapping Topics

Mapping Lessons

UnrealEd Interface

Questions&Answers

Scripting Topics

Scripting Lessons

Making Mods

Class Tree

Questions&Answers

Modeling Topics

Questions&Answers

Log In