atan2() / Reference / Processing.org

Name

atan2()

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 due the structure of calculating the tangent.

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);
}

Syntax

atan2(y, x)

Parameters

y(float)y-coordinate of the point
x(float)x-coordinate of the point

Return

float

tan()

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