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This reference is for Processing 3.0+. If you have a previous version, use the reference included with your software in the Help menu. If you see any errors or have suggestions, please let us know. If you prefer a more technical reference, visit the Processing Core Javadoc and Libraries Javadoc.

Name | ### atan2()
Examples |
    void draw() {
      background(204);
      translate(width/2, height/2);
      float a = atan2(mouseY-height/2, mouseX-width/2);
      rotate(a);
      rect(-30, -5, 60, 10);
    }
Description | Calculates the angle (in radians) from a specified point to the coordinate origin as measured from the positive x-axis. 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 y-coordinate of the point is the first parameter, and the x-coordinate is the second parameter, due the the structure of calculating the tangent.
Syntax |
    atan2(y, x)
Parameters |
y | float: y-coordinate of the point
x | float: x-coordinate of the point
Returns | float
Related | tan()

Updated on July 4, 2018 11:56:42am EDT