Difference between revisions of "LlAtan2"
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/Compass QA
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Or | Or | ||
< | <source lang="lsl2"> | ||
if((string)x != (string)0.0 && y == 0.0)//negative zero | if((string)x != (string)0.0 && y == 0.0)//negative zero | ||
return PI * ~-2*((string)y != (string)0.0)); | return PI * ~-2*((string)y != (string)0.0)); | ||
return ((y > 0) - (y < 0)) * PI_BY_TWO; | return ((y > 0) - (y < 0)) * PI_BY_TWO; | ||
</ | </source> | ||
The returned value is in the range {{Interval|gte=-[[PI]]|gteh=-PI|lte=PI|center=return}}{{Interval/Footnote}}. | The returned value is in the range {{Interval|gte=-[[PI]]|gteh=-PI|lte=PI|center=return}}{{Interval/Footnote}}. | ||
|caveats | |caveats | ||
|constants | |constants | ||
|examples=< | |examples=<source lang="lsl2">default | ||
{ | { | ||
state_entry() | state_entry() | ||
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llOwnerSay("The arctangent of y divided by x is " + (string)llAtan2(num1, num2)); | llOwnerSay("The arctangent of y divided by x is " + (string)llAtan2(num1, num2)); | ||
} | } | ||
}</ | }</source><source lang="lsl2">//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 | //a string with the literal compass-direction of that target towards your position | ||
//by Ramana Sweetwater 2009/01, any use allowed license :-) | //by Ramana Sweetwater 2009/01, any use allowed license :-) | ||
| Line 50: | Line 50: | ||
integer index = 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); | return llList2String(DIRS, index); | ||
}</ | }</source> | ||
[[/Compass QA]] | [[/Compass QA]] | ||
|helpers | |helpers | ||
Revision as of 22:28, 21 January 2015
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Summary
Function: float llAtan2( float y, float x );| 0.0 | Forced Delay |
| 10.0 | Energy |
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 and avoids division by zero.
Specification
If x is positive zero and...
- y is zero, zero is returned.
- y is positive, PI/2 is returned.
- y is negative, -PI/2 is returned.
If x is negative zero and...
- y is positive zero, PI is returned.
- y is negative zero, -PI is returned.
- y is positive, PI/2 is returned.
- y is negative, -PI/2 is returned.
Or
if((string)x != (string)0.0 && y == 0.0)//negative zero
return PI * ~-2*((string)y != (string)0.0));
return ((y > 0) - (y < 0)) * PI_BY_TWO;
Examples
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));
}
}
//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);
}
See Also
Deep Notes
Footnotes
- ^ The ranges in this article are written in Interval Notation.
Signature |
|---|
function float llAtan2( float y, float x ); |