#Codevember day13: Black Hole

//クリフォード・アトラクタ
// Xn+1 = sin( a * Yn ) + c * cos( a * Xn )
// Yn+1 = sin( b * Xn ) + d * cos( b * Yn )

//係数
let a = 1.374;
let b = -1.764;
let c = 1.582;
let d = 1.056;

//プロットする点，漸化式のn+1
let dx, dy;

//点と初期値
let x = 0;
let y = 0;

function setup() {
    createCanvas(windowWidth, windowHeight);
    background(0);
    
    translate(width / 2, height / 2);
    for (let i = 0; i < 500000; i++) {
        //2-3行目の公式をそのまま使う
        dx = sin(a * y) + c * cos(a * x);
        dy = sin(b * x) + d * cos(b * y);
        x = dx;
        y = dy;
        stroke(255, 45);
        point(x * width / 6, y * width / 6);
    }
}