llRotBetween

From Second Life Wiki
Revision as of 23:51, 19 September 2007 by Strife Onizuka (talk | contribs)
Jump to navigation Jump to search

Summary

Function: rotation llRotBetween( vector start, vector end );
0.0 Forced Delay
10.0 Energy

Returns a rotation that is the rotation between the direction start and the direction end

• vector start
• vector end

Specification

start and end are directions and are relative to the origin <0.0, 0.0, 0.0>. If you have coordinates relative to a different origin, subtract that origin from the input vectors.

Caveats

  • start * llRotBetween(start, end) == end is only true if start and end have the same magnitude and neither have a magnitude of zero (see #Notes for a workaround).

Examples

llRotBetween(<1.0, 0.0, 0.0>, <0.0, -1.0, 0.0>)
// will return <0.00000, 0.00000, -0.70711, 0.70711> (which represents -45 degrees on the z axis)

llRotBetween(<0.0, 0.0, 0.0>, <0.0, -1.0, 0.0>)
// will return <0.00000, 0.00000, 0.00000, 1.00000> (which represents a zero angle on all axis)
// because <0.0, 0.0, 0.0> does not convey a direction.

Notes

This function adjusts the magnitude of the quaternion so start * llRotBetween(start, end) == end is true as long as neither have a magnitude of zero. They don't have to have the same magnitude.

rotation RotBetween(vector start, vector end) //adjusts quaternion magnitude so (start * return == end) 
{//Authors note: I have never had a use for this but it's good to know how to do it if I did.
    rotation rot = llRotBetween(start, end);
    if(start)
    {
        if(end)
        {
            float d = llSqrt(llVecMag(end) / llVecMag(start));
            return <rot .x * d, rot .y * d, rot .z * d, rot .s * d>;
        }
    }
    return rot;
}//Strife Onizuka

See Also

Functions

•  llAngleBetween

Deep Notes

Signature

function rotation llRotBetween( vector start, vector end );