Difference between revisions of "LlRot2Up"

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(Added a note to remind people that they can use <0.0, 0.0, 1.0>*rot instead of llRot2Up(rot) with unit quaternions. I always see people using llRot2* in fast-running code when it can be simplified.)
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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:
<lsl>ret = <0., 0., 1.> * q;</lsl>
<lsl>ret = <0., 0., 1.> * q;</lsl>
Keep in mind that object and agent rotations will always be unit quaternions. For example, <0.0, 0.0, 1.0>*llGetRot() is about 25-30% faster than llRot2Up(llGetRot()) depending on the VM used. If done often and at extremely fast rates, it can be advantageous to even save <0.0, 0.0, 1.0> to a local/global variable and reuse it.
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Revision as of 18:35, 20 July 2012

Summary

Function: vector llRot2Up( rotation q );

Computes the orientation of the local z-axis relative to the earth.
Returns a vector that is the up vector defined by q, i.e. a unit vector pointing in the positive Z direction

• rotation q

Can be useful to identify the orientation of the local horizontal-plane of the prim, since it's z-axis is always perpendicular to this local horizontal plane.

Specification

Mathematically equivalent to: <lsl>ret = llVecNorm(<0., 0., 1.> * q);</lsl> If q is known to be a unit quaternion then it can be simplified as: <lsl>ret = <0., 0., 1.> * q;</lsl> Keep in mind that object and agent rotations will always be unit quaternions. For example, <0.0, 0.0, 1.0>*llGetRot() is about 25-30% faster than llRot2Up(llGetRot()) depending on the VM used. If done often and at extremely fast rates, it can be advantageous to even save <0.0, 0.0, 1.0> to a local/global variable and reuse it.

Examples

See Also

Functions

•  llRot2Left
•  llRot2Fwd
•  llRot2Axis
•  llRot2Angle

Deep Notes

Search JIRA for related Issues

Signature

function vector llRot2Up( rotation q );