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.)
(Provide an example)
Line 13: Line 13:
|caveats
|caveats
|constants
|constants
|examples
|examples=
<lsl>
// Move an object 5 metres forwards along its own z axis, when touched, no matter how the object is oriented in world.
default
{
    touch_start(integer total_number)
    {
        vector v = llRot2Up( llGetRot() );
        llSetPos( llGetPos() + v * 5.0 );
    }
}
</lsl>
|helpers
|helpers
|also_functions=
|also_functions=

Revision as of 08:03, 6 December 2013

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

<lsl> // Move an object 5 metres forwards along its own z axis, when touched, no matter how the object is oriented in world. default {

   touch_start(integer total_number)
   {
       vector v = llRot2Up( llGetRot() );
       llSetPos( llGetPos() + v * 5.0 );
   }

}

</lsl>

See Also

Functions

•  llRot2Left
•  llRot2Fwd
•  llRot2Axis
•  llRot2Angle

Deep Notes

Signature

function vector llRot2Up( rotation q );