import { zeroVector } from "./zero-vector.js";

const { PI, sin, cos } = Math;


/**
 * Returns the result of rotating a vector around a specified point.
 * 
 * @param θ angle
 * @param c center of rotation
 */
function rotateVectorAround(
        θm: number,
        c = zeroVector,
        v: number[]) {

    const x = v[0];
    const y = v[1];

    const θ = θm*PI/12;
    const cosθ = cos(θ);
    const sinθ = sin(θ);

    const [cx,cy] = c;
    const vx = x - cx;
    const vy = y - cy;

    return [
        cosθ*vx - sinθ*vy + cx,
        sinθ*vx + cosθ*vy + cy
    ];
}


export { rotateVectorAround }