Reference for Processing version 1.2. If you have a previous version, use the reference included with your software. If you see any errors or have suggestions, please let us know.
If you prefer a more technical reference, visit the Processing Javadoc.
Name 
atan2() 
Examples 
void draw() {
background(204);
translate(width/2, height/2);
float a = atan2(mouseYheight/2, mouseXwidth/2);
rotate(a);
rect(12, 5, 24, 10);
} 
Description 
Calculates the angle (in radians) from a specified point to the coordinate origin as measured from the positive xaxis. Values are returned as a float in the range from PI to PI. The atan2() function is most often used for orienting geometry to the position of the cursor. Note: The ycoordinate of the point is the first parameter and the xcoordinate is the second due the the structure of calculating the tangent. 
Syntax 
atan2(y, x); 
Parameters 
y 
int or float: ycoordinate of the point 
x 
int or float: xcoordinate of the point 

Returns 
float 
Usage 
Web & Application 
Related 
tan()

Updated on June 14, 2010 12:05:29pm EDT