# Difference between revisions of "LlRot2Fwd"

Omei Qunhua (Talk | contribs) m (as llRot2Up etc.) |
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|return_text=that is the forward vector defined by {{LSLP|q}}, i.e. a unit vector pointing in the local positive X direction. | |return_text=that is the forward vector defined by {{LSLP|q}}, i.e. a unit vector pointing in the local positive X direction. | ||

|spec=Mathematically equivalent to: | |spec=Mathematically equivalent to: | ||

− | < | + | <source lang="lsl2">ret = llVecNorm(<1., 0., 0.> * q);</source> |

If {{LSLP|q}} is known to be a unit quaternion then it can be simplified as: | If {{LSLP|q}} is known to be a unit quaternion then it can be simplified as: | ||

− | < | + | <source lang="lsl2">ret = <1., 0., 0.> * q;</source> |

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. | 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. | ||

|caveats | |caveats | ||

|constants | |constants | ||

|examples= | |examples= | ||

− | < | + | <source lang="lsl2"> |

// Move an object 5 metres forwards along its x axis, when touched, no matter how the object is oriented in world. | // 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 | // Works for a root or child prim | ||

Line 24: | Line 24: | ||

} | } | ||

} | } | ||

− | </ | + | </source> |

|helpers | |helpers | ||

|also_functions= | |also_functions= |

## Latest revision as of 14:35, 22 January 2015

LSL Portal | Functions | Events | Types | Operators | Constants | Flow Control | Script Library | Categorized Library | Tutorials |

## Summary

Function: vector**llRot2Fwd**( rotation q );

18 | Function ID |

0.0 | Forced Delay |

10.0 | 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.

## Caveats

## 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.

## See Also

### Functions

• | llRot2Left | |||

• | llRot2Up | |||

• | llRot2Axis | |||

• | llRot2Angle |