<canvas id="riemannCanvas"></canvas>
function mapRange(value, inMin, inMax, outMin, outMax){
function lerp(a,b,t){ return a + (b-a)*t; }
function fade(t){ return t*t*t*(t*(t*6 -15)+10); }
function noise2D(x,y){
let xi = Math.floor(x), yi= Math.floor(y);
let xf= x-xi, yf= y-yi;
let r1 = randomCell2D(xi, yi);