---
title: Collision Types
slug: /collisiontypes
section: Physics
---

Colliders have the default collision type of [[CollisionType.Passive]], this is so colliders don't accidentally opt into something computationally expensive. **In order for colliders to participate in collisions** and the global physics system, colliders **must** have a collision type of [[CollisionType.Active]] or [[CollisionType.Fixed]].

### Prevent

Actors with the [[CollisionType.PreventCollision]] setting do not participate in any
collisions and do not raise collision events.

### Passive

Actors with the [[CollisionType.Passive]] setting only raise collision events, but are not
influenced or moved by other actors and do not influence or move other actors.

### Active

Actors with the [[CollisionType.Active]] setting raise collision events and participate
in collisions with other actors and will be push or moved by actors sharing
the [[CollisionType.Active]] or [[CollisionType.Fixed]] setting.

### Fixed

Actors with the [[CollisionType.Fixed]] setting raise collision events and participate in
collisions with other actors. Actors with the [[CollisionType.Fixed]] setting will not be
pushed or moved by other actors sharing the [[CollisionType.Fixed]].

Think of `Fixed` actors as "immovable/unstoppable" objects. If two [[CollisionType.Fixed]] actors
meet they will not be pushed or moved by each other, they will not interact except to throw
collision events.

### Collision Type Behavior Matrix

This matrix shows what will happen with 2 actors of any collision type.

| Collision Type | Prevent |   Passive   |       Active        |        Fixed        |
| -------------- | :-----: | :---------: | :-----------------: | :-----------------: |
| Prevent        |  None   |    None     |        None         |        None         |
| Passive        |  None   | Events Only |     Events Only     |     Events Only     |
| Active         |  None   | Events Only | Resolution & Events | Resolution & Events |
| Fixed          |  None   | Events Only | Resolution & Events |        None         |

- None = No collision resolution and no collision events
- Events Only = No resolution is performed, only collision events are fired on colliders, except for `postcollision` which only fires if resolution was performed.
- Resolution & Events = Collider positions are resolved according to their collision type and collision events are fired on both colliders
