llRot2Left

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Revision as of 11:59, 6 December 2013 by Omei Qunhua (talk | contribs) (As llRot2Fwd etc.)
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Summary

Function: vector llRot2Left( rotation q );

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

• rotation q

Specification

Mathematically equivalent to: <lsl>ret = llVecNorm(<0., 1., 0.> * q);</lsl> If q is known to be a unit quaternion then it can be simplified as: <lsl>ret = <0., 1., 0.> * q;</lsl> Keep in mind that object and agent rotations will always be unit quaternions. For example, <0.0, 1.0, 0.0>*llGetRot() is about 25-30% faster than llRot2Left(llGetRot()) depending on the VM used. If done often and at extremely fast rates, it can be advantageous to even save <0.0, 1.0, 0.0> to a local/global variable and reuse it.

Examples

<lsl> // Move an object 5 metres forwards along its own y 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 = llRot2Left( llGetLocalRot() );
       llSetPos( llGetLocalPos() + v * 5 );
   }

}

</lsl>

Notes

Can be useful to identify the orientation of the local "Wikipedia logo"sagittal-plane of the prim, since it's y-axis is always perpendicular to this local sagittal-plane.

See Also

Functions

•  llRot2Up
•  llRot2Fwd
•  llRot2Axis
•  llRot2Angle

Deep Notes

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Signature

function vector llRot2Left( rotation q );