Difference between revisions of "LlAtan2"

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m (Mathematically speaking I don't think there was anything wrong with the previous version (i think they are equivalent) regardless, spaces are needed, it's an example after all!)
Line 32: Line 32:
 
     vector source = llGetPos();
 
     vector source = llGetPos();
 
     list DIRS =["W","NW","N","NE","E","SE","S","SW","W"];
 
     list DIRS =["W","NW","N","NE","E","SE","S","SW","W"];
     return llList2String(DIRS,llCeil(3.5-((4*llAtan2((target.y-source.y),(target.x-source.x)))/PI)));
+
     integer index = llCeil(3.5 - (4 * llAtan2(target.y - source.y, target.x - source.x) / PI));
 +
    return llList2String(DIRS, index);
 
}</lsl>
 
}</lsl>
 
[[/Compass QA]]
 
[[/Compass QA]]

Revision as of 21:59, 27 November 2010

Summary

Function: float llAtan2( float y, float x );

Returns a float that is the arctangent2 of y, x.

• float y
• float x

Similar to the arctangent(y/x) except it utilizes the signs of x & y to determine the quadrant. Returns zero if x and y are zero.
The returned value is in the range [-PI, PI][1].

Examples

<lsl>default {

 state_entry()
 {
   float num1 = llFrand(100.0);
   float num2 = llFrand(100.0);
   llOwnerSay("y = " + (string)num1);
   llOwnerSay("x = " + (string)num2);
   llOwnerSay("The arctangent of y divided by x is " + (string)llAtan2(num1, num2));
 }

}</lsl><lsl>//Function with input of a vector determining the position of a target and returning //a string with the literal compass-direction of that target towards your position //by Ramana Sweetwater 2009/01, any use allowed license :-) //corrected by Patrick Muggins

string compass (vector target) {

   vector source = llGetPos();
   list DIRS =["W","NW","N","NE","E","SE","S","SW","W"];
   integer index = llCeil(3.5 - (4 * llAtan2(target.y - source.y, target.x - source.x) / PI));
   return llList2String(DIRS, index);

}</lsl>

/Compass QA

See Also

Functions

• llSin llAsin sine & inverse Sine
• llCos llAcos cosine & inverse cosine
• llTan tangent

Articles

•  Wikipedia:Atan2
•  Wikipedia:Inverse_trigonometric_function

Deep Notes

Search JIRA for related Issues

Footnotes

  1. ^ The ranges in this article are written in Interval Notation.

Signature

function float llAtan2( float y, float x );