llRot2Angle
Revision as of 21:17, 2 September 2012 by Strife Onizuka (talk | contribs)
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Summary
Function: float llRot2Angle( rotation rot );| 171 | Function ID |
| 0.0 | Forced Delay |
| 10.0 | Energy |
Returns a float that is the rotation angle represented by rot
| • rotation | rot |
Use in conjunction with llRot2Axis.
To undo use llAxisAngle2Rot.
Caveats
This always returns a positive angle <= PI radians, that is, it is the unsigned minimum angle. A rotation of 3/2 PI radians (270 degrees) will return an angle of PI / 2 radians, not -PI / 2.
Examples
See Also
Functions
| • | llAxisAngle2Rot | |||
| • | llRot2Axis | |||
| • | llRot2Up | |||
| • | llRot2Fwd | |||
| • | llRot2Left | |||
| • | llAngleBetween | – | Similar functionality. |
Deep Notes
Reference Implementation
<lsl>float Rot2Angle(rotation a)//simple but turns out to not be very accurate. {
return 2.0 * llAcos(llSqrt((a.s * a.s) / (a.x * a.x + a.y * a.y + a.z * a.z + a.s * a.s));
}</lsl>
<lsl>float Rot2Angle(rotation r)//more complex implementation but more accurate, and reasonably fast. {
float s2 = r.s * r.s; // square of the s-element float v2 = r.x * r.x + r.y * r.y + r.z * r.z; // sum of the squares of the v-elements
if (s2 < v2) // compare the s-component to the v-component
return 2.0 * llAcos(llSqrt(s2 / (s2 + v2))); // use arccos if the v-component is dominant
else if (v2) // make sure the v-component is non-zero
return 2.0 * llAsin(llSqrt(v2 / (s2 + v2))); // use arcsin if the s-component is dominant
return 0.0; // argument is scaled too small to be meaningful, or it is a zero rotation, so return zero
}//Written by Moon Metty & Miranda Umino. Minor optimizations by Strife Onizuka</lsl>
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Signature |
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function float llRot2Angle( rotation rot ); |