// Forked from "our new land" by ge1doot
// https://turtletoy.net/turtle/b2fdeed2d8

const turtle = new Turtle();

const seed = 100; // min=1, max=200, step=1
const scaleX = 5; // min=1, max=20, step=0.01
const scaleY = 8; // min=1, max=20, step=0.01
const step = 2; // min=0.1, max=5, step=0.1
const quality = 0.5; // min=0.001, max=1, step=0.001

const noise = new SimplexNoise(seed);
let y = 100;
const line = Array.from({ length: 200 }, () => 100);

function walk(i) {
    y -= 1 - quality;
	turtle.jump(-100, y);
	let v = false;
	for (let x = -100; x <= 100; x+=step) {
		let z = y +	0.25 * (
		    (256 * noise.noise2D([x * 0.005 * scaleX, 6 + y * 0.005 * scaleY])) & (0  + 32 + 64 + 512)
		);
		if (z > -100) v = true;
		if (z > line[x]) z = line[x] - 0.0005;
		line[x] = z;
		turtle.goto(x, z);
	}
	return v;
}



////////////////////////////////////////////////////////////////
// Simplex Noise utility code. Created by Reinder Nijhoff 2020
// https://turtletoy.net/turtle/6e4e06d42e
// Based on: http://webstaff.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
////////////////////////////////////////////////////////////////
function SimplexNoise(seed = 1) {
	const grad = [  [1, 1, 0], [-1, 1, 0], [1, -1, 0], [-1, -1, 0],
	            	[1, 0, 1], [-1, 0, 1], [1, 0, -1], [-1, 0, -1],
            		[0, 1, 1], [0, -1, 1], [0, 1, -1], [0, -1, -1] ];
	const perm = new Uint8Array(512);
            		
	const F2 = (Math.sqrt(3) - 1) / 2, F3 = 1/3;
	const G2 = (3 - Math.sqrt(3)) / 6, G3 = 1/6;

	const dot2 = (a, b) => a[0] * b[0] + a[1] * b[1];
	const sub2 = (a, b) => [a[0] - b[0], a[1] - b[1]];
	const dot3 = (a, b) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
	const sub3 = (a, b) => [a[0] - b[0], a[1] - b[1], a[2] - b[2]];

	class SimplexNoise {
		constructor(seed = 1) {
			for (let i = 0; i < 512; i++) {
				perm[i] = i & 255;
			}
			for (let i = 0; i < 255; i++) {
				const r = (seed = this.hash(i+seed)) % (256 - i)  + i;
				const swp = perm[i];
				perm[i + 256] = perm[i] = perm[r];
				perm[r + 256] = perm[r] = swp;
			}
		}
		noise2D(p) {
			const s = dot2(p, [F2, F2]);
			const c = [Math.floor(p[0] + s), Math.floor(p[1] + s)];
			const i = c[0] & 255, j = c[1] & 255;
			const t = dot2(c, [G2, G2]);

			const p0 = sub2(p, sub2(c, [t, t]));
			const o  = p0[0] > p0[1] ? [1, 0] : [0, 1];
			const p1 = sub2(sub2(p0, o), [-G2, -G2]);
			const p2 = sub2(p0, [1-2*G2, 1-2*G2]);
			
			let n =  Math.pow(Math.max(0, 0.5-dot2(p0, p0)),4) * dot2(grad[perm[i+perm[j]] % 12], p0);
			    n += Math.pow(Math.max(0, 0.5-dot2(p1, p1)),4) * dot2(grad[perm[i+o[0]+perm[j+o[1]]] % 12], p1);
		    	n += Math.pow(Math.max(0, 0.5-dot2(p2, p2)),4) * dot2(grad[perm[i+1+perm[j+1]] % 12], p2);
			
			return 70 * n;
		}
		hash(i) {
            i = 1103515245 * ((i >> 1) ^ i);
            const h32 = 1103515245 * (i ^ (i>>3));
            return h32 ^ (h32 >> 16);
		}
	}
	return new SimplexNoise(seed);
}