# Difference between revisions of "LlRot2Fwd"

 LSL Portal

## Contents

Function: vector llRot2Fwd( rotation q );
 18 Function ID 0 Forced Delay 10 Energy

Computes the orientation of the local x-axis relative to the parent (i.e. the root prim or the world).
Returns a vector that is the forward vector defined by q, i.e. a unit vector pointing in the local positive X direction.

 • rotation q

## Specification

Mathematically equivalent to:

`ret = llVecNorm(<1., 0., 0.> * q);`

If q is known to be a unit quaternion then it can be simplified as:

`ret = <1., 0., 0.> * q;`

Keep in mind that object and agent rotations will always be unit quaternions. For example, <1.0, 0.0, 0.0>*llGetRot() is about 25-30% faster than llRot2Fwd(llGetRot()) depending on the VM used. If done often and at extremely fast rates, it can be advantageous to even save <1.0, 0.0, 0.0> to a local/global variable and reuse it.

## Examples

```// Move an object 5 metres forwards along its x axis, when touched, no matter how the object is oriented in world.
// Works for a root or child prim
default
{
touch_start(integer total_number)
{
vector v = llRot2Fwd( llGetLocalRot() );
llSetPos( llGetLocalPos() + v * 5 );
}
}```

## Notes

Can be useful to identify the orientation of the local frontal-plane of the prim, since its x-axis is always perpendicular to this local frontal plane.

```function vector llRot2Fwd( rotation q );