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circle.ts
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circle.ts
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import { squaredDistanceBetween } from 'flo-vector2d';
/**
* Canonical circle representation.
*/
class Circle {
/**
* @param center The center.
* @param radius The radius.
*/
constructor(
public readonly center: number[],
public readonly radius: number) {
}
/**
* Returns a scaled version of the given circle without changing its center.
* @param circle
* @param s multiplier
*/
public static scale(circle: Circle, s: number) {
return new Circle(circle.center, circle.radius * s)
}
/**
* Returns true if the first circle engulfs the second.
* @param c1
* @param c2
*/
public static engulfsCircle(c1: Circle, c2: Circle) {
if (c1.radius <= c2.radius) {
return false;
}
let d = squaredDistanceBetween(c1.center, c2.center);
let dr = c1.radius - c2.radius;
let δ = dr*dr;
return δ > d;
}
/**
* Returns a human-readable string description of the given circle.
* @param circle
*/
public static toString(circle: Circle): string {
return 'c: ' + circle.center + ' r: ' + circle.radius;
}
}
export { Circle };