# collision

*LSL event*

```lsl
collision(integer num_detected)
```

- `integer num_detected`: Total number of detected colliders (usable with llDetected* functions).

Triggered continuously while an avatar or another object is colliding with the object containing the script. Passes num_detected, representing the number of detected collisions.

Triggered while task is [colliding](https://wiki.secondlife.com/wiki/colliding) with another task.

```lsl title="How to use" frame="terminal"
collision(integer num_detected)
{

}
```

## Caveats

- Max number detected is 8.
- Smallest repeat rate is approximatively 0.13 seconds.
- Will not detect collisions with [ground](https://wiki.secondlife.com/wiki/ground); use [land_collision](/events/land_collision/) instead.
- Will not detect collisions between an avatar sitting on the task and the task itself (avatars are linked to objects they sit on so there is no collision, use the [changed](/events/changed/) event to detect sits).
- Phantom objects can never receive trigger collision events.
- `llVolumeDetect(TRUE)` objects get trigger [collision_start](/events/collision_start/) and [collision_end](/events/collision_end/) but not [collision](/events/collision/)() events.
- A collision with a hovering avatar does not trigger collisions, unless the avatar turns or moves.
- A collision with a physical object or avatar resting on object does not continuously trigger collisions but for a few times, unless there is movement.
- Only a physical object will get collision events from colliding with a non-physical object.

## Examples

<details open>
<summary>Example 1</summary>

```lsl
//Will turn phantom when someone bumps into it if on the list

list access_list = ["Governor Linden"];

default
{
    collision(integer num_detected)
    {
        if(~llListFindList(access_list, (list)llDetectedName(0)))
        {
            llSetStatus(STATUS_PHANTOM, TRUE);
        }
    }
}
```

</details>

## Known issues

- [SVC-3306](https://jira.secondlife.com/browse/SVC-3306): Add enumeration to [llPassCollisions](/functions/llPassCollisions/)() to provide [PASS_ALWAYS](/constants/PASS_ALWAYS/), [PASS_IF_NOT_HANDLED](/constants/PASS_IF_NOT_HANDLED/), and [PASS_NEVER](/constants/PASS_NEVER/) as explicit options.

  (Was: [Collision](https://wiki.secondlife.com/wiki/Category:LSL_Collision)s passed to parent REGARDLESS [llPassCollisions](/functions/llPassCollisions/)([FALSE](/constants/FALSE/)) in child)

## See also

### Functions

- [llPassCollisions](/functions/llPassCollisions/)
- [llCollisionFilter](/functions/llCollisionFilter/)
- [llCollisionSound](/functions/llCollisionSound/)
- [llVolumeDetect](/functions/llVolumeDetect/)

### Events

- [collision_start](/events/collision_start/)
- [collision_end](/events/collision_end/)

---

*Source: [Collision](https://wiki.secondlife.com/wiki/Collision) on the Second Life Wiki. Content from the Second Life Wiki article Collision (revision 1211066, 2022-08-24), CC BY-SA 3.0.*

---

From lsl.dev: https://lsl.dev/events/collision/