Difference between revisions of "LlRot2Up"

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{{LSLFunctionAll|func_id=20|func_sleep=0.0|func_energy=10.0|func=llRot2Up|return_type=vector|p1_type=rotation|p1_name=q|func_footnote=returns the up vector defined by q}}[[Category:LSL_Functions]][[Category:LSL_Stub]]
{{LSL_Function
|func_id=20|func_sleep=0.0|func_energy=10.0
|func=llRot2Up|sort=Rot2Up
|return_type=vector|p1_type=rotation|p1_name=q
|func_desc=Computes the orientation of the {{HoverText|local z-axis|up-direction of prim}} relative to the parent (i.e. the root prim or the world).
|return_text=that is the up vector defined by {{LSLP|q}}, i.e. a unit vector pointing in the positive Z direction
|spec=Mathematically equivalent to:
<source lang="lsl2">ret = llVecNorm(<0., 0., 1.> * q);</source>
If {{LSLP|q}} is known to be a unit quaternion then it can be simplified as:
<source lang="lsl2">ret = <0., 0., 1.> * q;</source>
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
|constants
|examples=
<source lang="lsl2">
// Move a prim 5 metres forwards along its own z 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 = llRot2Up( llGetLocalRot() );
        llSetPos( llGetLocalPos() + v * 5 );
    }
}
</source>
|helpers
|also_functions=
{{LSL DefineRow||[[llRot2Left]]|}}
{{LSL DefineRow||[[llRot2Fwd]]|}}
{{LSL DefineRow||[[llRot2Axis]]|}}
{{LSL DefineRow||[[llRot2Angle]]|}}
|also_tests
|also_events
|also_articles
|notes=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.
|permission
|inventory
|negative_index
|cat1=Rotation
|cat2
|cat3
|cat4
}}

Latest revision as of 14:37, 22 January 2015

Summary

Function: vector llRot2Up( rotation q );

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

• rotation q

Specification

Mathematically equivalent to:

ret = llVecNorm(<0., 0., 1.> * q);

If q is known to be a unit quaternion then it can be simplified as:

ret = <0., 0., 1.> * q;

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

// Move a prim 5 metres forwards along its own z 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 = llRot2Up( llGetLocalRot() );
        llSetPos( llGetLocalPos() + v * 5 );
    }
}

Notes

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.

See Also

Functions

•  llRot2Left
•  llRot2Fwd
•  llRot2Axis
•  llRot2Angle

Deep Notes

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Signature

function vector llRot2Up( rotation q );