Difference between revisions of "LlRot2Fwd"

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(Provide an example)
m (Correct initial statement re: child prims, and adjust example to for both root and child prims)
Line 3: Line 3:
 
|func=llRot2Fwd|sort=Rot2Fwd
 
|func=llRot2Fwd|sort=Rot2Fwd
 
|return_type=vector|p1_type=rotation|p1_name=q
 
|return_type=vector|p1_type=rotation|p1_name=q
|func_desc=Computes the orientation of the {{HoverText|local x-axis|front-direction of prim}} relative to {{HoverLink|Viewer_coordinate_frames#Global|global coordinate system|the earth}}.
+
|func_desc=Computes the orientation of the {{HoverText|local x-axis|front-direction of prim}} relative to the parent (i.e. the root prim or the world).
 
|return_text=that is the forward vector defined by {{LSLP|q}}, i.e. a unit vector pointing in the local positive X direction.
 
|return_text=that is the forward vector defined by {{LSLP|q}}, i.e. a unit vector pointing in the local positive X direction.
 
|func_footnote=Can be useful to identify the orientation of the local {{HoverText|frontal-plane|coronal-plane}} of the prim, since it's x-axis is always perpendicular to this local frontal plane.
 
|func_footnote=Can be useful to identify the orientation of the local {{HoverText|frontal-plane|coronal-plane}} of the prim, since it's x-axis is always perpendicular to this local frontal plane.
Line 20: Line 20:
 
     touch_start(integer total_number)
 
     touch_start(integer total_number)
 
     {
 
     {
         vector v = llRot2Fwd( llGetRot() );
+
         vector v = llRot2Fwd( llGetLocalRot() );
         llSetPos( llGetPos() + v * 5.0 );
+
         llSetPos( llGetLocalPos() + v * 5 );
 
     }
 
     }
 
}
 
}

Revision as of 10:38, 6 December 2013

Summary

Function: vector llRot2Fwd( rotation q );

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

• rotation q

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

Specification

Mathematically equivalent to: <lsl>ret = llVecNorm(<1., 0., 0.> * q);</lsl> If q is known to be a unit quaternion then it can be simplified as: <lsl>ret = <1., 0., 0.> * q;</lsl> Keep in mind that object and agent rotations will always be unit quaternions. For example, <1.0, 0.0, 0.0>*llGetRot() is about 25-30% faster than llRot2Fwd(llGetRot()) depending on the VM used. If done often and at extremely fast rates, it can be advantageous to even save <1.0, 0.0, 0.0> to a local/global variable and reuse it.

Examples

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

   touch_start(integer total_number)
   {
       vector v = llRot2Fwd( llGetLocalRot() );
       llSetPos( llGetLocalPos() + v * 5 );
   }

}

</lsl>

See Also

Functions

•  llRot2Left
•  llRot2Up
•  llRot2Axis
•  llRot2Angle

Deep Notes

Search JIRA for related Issues

Signature

function vector llRot2Fwd( rotation q );