The atan2() CSS function is a trigonometric function that returns the inverse tangent of two values between -infinity and infinity. The function accepts two arguments and returns the number of radians representing an <angle>() between -180deg and 180deg.
Syntax
/* Two <number> values */ transform: rotate(atan2(3, 2)); /* Two <dimension> values */ transform: rotate(atan2(1rem, -0.5rem)); /* Two <percentage> values */ transform: rotate(atan2(20%, -30%)); /* Other values */ transform: rotate(atan2(pi, 45)); transform: rotate(atan2(e, 30));
Parameters
The atan2(y, x) function accepts two comma-separated values as its parameters. Each value can be a <number>(), a <dimension>(), or a <percentage>(). Both values must be of the same type, although if they are <dimension>() they can be of different units (example: atan2(100px, 5vw) is valid).
y-
The y-coordinate of the point. A calculation which resolves to a
<number>(), a<dimension>(), or a<percentage>(). x-
The x-coordinate of the point. A calculation which resolves to a
<number>(), a<dimension>(), or a<percentage>().
Return value
Given two values x and y, the function atan2(y, x) calculates and returns the <angle>() between the positive x-axis and the ray from the origin to the point (x, y).
Examples
Rotate elements
The atan2() function can be used to rotate elements as it return an <angle>().
HTML
<div class="box box-1"></div> <div class="box box-2"></div> <div class="box box-3"></div> <div class="box box-4"></div> <div class="box box-5"></div>
CSS
div.box {
width: 100px;
height: 100px;
background: linear-gradient(orange, red);
}
div.box-1 {
transform: rotate(atan2(3, 2));
}
div.box-2 {
transform: rotate(atan2(3%, -2%));
}
div.box-3 {
transform: rotate(atan2(-1, 0.5));
}
div.box-4 {
transform: rotate(atan2(1, 0.5));
}
div.box-5 {
transform: rotate(atan2(1rem, -0.5rem));
}