Circle.js is a collection of functions to work with circles. The aim is to have a fast and correct library, which makes it easy to calculate the intersection of circles, the area of a circle and so on.

Every circle is defined by a cartesian point (x, y) and the radius r.

Circles.js is analogous to Rectangles.js and Angles.js.

var circle = require('circle.js');
var A = {x: 20, y: 20, r: 10};
var B = {x: 80, y: 80, r: 30};
if (circle.intersect(A, B)) {
  console.log(circle.intersection(A, B)); // Intersection points
  console.log(circle.intersectionArea(A, B)); // Intersection area
} else {
  console.log("no intersection");
}

Determines if two circles intersect

Calculates the intersection points of two circles

Calculates the intersection area of two circles

Calculates the area of a circle

Calculates the height of a circle. Obviously, this is the same as the width.

Calculates the width of a circle. Obviously, this is the same as the height.

Calculates the perimeter of a circle

Calculates the center point of a circle. Simply it's coordinates.

Resizes the circle by a given value on the center

Caclulates a circle {x, y, r} with given three {x, y} points

Installing Circle.js is as easy as cloning this repo or use one of the following commands:

bower install circle

or

npm install circle.js

<script src="circle.js"></script>
<script>
console.log(Circle.center(A));
</script>

<script src="require.js"></script>
<script>
requirejs(['circle.js'],
function(Circle) {
    console.log(Circle.intersectionArea(A, B));
});
</script>

As every library I publish, Circle.js is also built to be as small as possible after compressing it with Google Closure Compiler in advanced mode. Thus the coding style orientates a little on maxing-out the compression rate. Please make sure you keep this style if you plan to extend the library.

If you plan to enhance the library, make sure you add test cases and all the previous tests are passing. You can test the library with

npm test

Copyright (c) 2016, Robert Eisele Licensed under the MIT license.