// Chaos Game. Created by Reinder Nijhoff 2020
// @reindernijhoff
//
// https://turtletoy.net/turtle/f4ef806547
//

Canvas.setpenopacity(.1);

const turtle = new Turtle();

const numVertices = 5; // min=3, max=7, step=1
const lerpDist    = 0.61803398875; // min=0.5, max=0.75, step=0.0000001
const mode        = 0; // min=0, max=2, step=1
const neighbor    = 1; // min=0, max=3, step=1

// create shape with numCorners vertices
const vertices = [];
for (let i=0; i<numVertices; i++) {
    const a = (i+1/4) / numVertices * Math.PI * 2;
    vertices.push([80*Math.cos(a), 80*Math.sin(a)]);
}


let randomIndex = 0, newRandomIndex = 0, prevRandomIndex;

function neighbors(i, j, n) {
    return i == (j + n) % numVertices || (i + n) % numVertices == j;
}

function walk(i) {
    // choose a random corner of the shape
    do {
        newRandomIndex = Math.random()*numVertices|0;
    } while (
          (mode == 1 && neighbors(randomIndex, newRandomIndex, neighbor)) || 
          (mode == 2 && prevRandomIndex == randomIndex && neighbors(randomIndex, newRandomIndex, neighbor))
    );
    prevRandomIndex = randomIndex;
    randomIndex = newRandomIndex;
    
    // jump turtle somewhere halfway (at lerpDist) between current position of turtle
    // and the randomly chosen vertex
    const c = [turtle.x(), turtle.y()];
    const n = vertices[newRandomIndex];
    turtle.jump([lerpDist*n[0] + (1-lerpDist)*c[0], lerpDist*n[1] + (1-lerpDist)*c[1]]);
    
    // draw small circle
    turtle.circle(.1);
    
    return i < 250000;
}