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. | |||
|caveats | |caveats | ||
|constants | |constants | ||
Revision as of 17:35, 20 July 2012
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Summary
Function: vector llRot2Up( rotation q );| 0.0 | Forced Delay |
| 10.0 | Energy |
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
Signature |
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function vector llRot2Up( rotation q ); |