// --------------------------------------------------------------------
// UNIT 5 – List Toy
// Title: Mohr Cube Grid (Data-Driven Placement)
//
// PSEUDOCODE
// define line(x1,y1,x2,y2) → draw a segment
// define drawCube(x, y) → draw all 12 cube edges using vertex offsets
//
// create a list of cube positions: [{x,y}, {x,y}, ... ]
//
// for each entry in the list:
//     draw a cube at that position
//
// This demonstrates:
//     - lists as data containers
//     - iterating across lists
//     - one function reused many times
// --------------------------------------------------------------------

Canvas.setpenopacity(1);
const t = new Turtle();

// --------------------------------------------------
// Helper: draw a single line segment between 2 points
function line(x1, y1, x2, y2) {
    t.penup();
    t.goto(x1, y1);
    t.pendown();
    t.goto(x2, y2);
}

// --------------------------------------------------
// Draw cube wireframe at (x, y)
// Geometry scaled and angled for visual clarity
function drawCube(x, y) {
    const s  = 30;   // edge length
    const dx = 18;   // x shift for back face
    const dy = -13;  // y shift for back face

    // FRONT
    const A = {x:x,     y:y};
    const B = {x:x+s,   y:y};
    const C = {x:x+s,   y:y-s};
    const D = {x:x,     y:y-s};

    // BACK (offset)
    const E = {x:A.x+dx, y:A.y+dy};
    const F = {x:B.x+dx, y:B.y+dy};
    const G = {x:C.x+dx, y:C.y+dy};
    const H = {x:D.x+dx, y:D.y+dy};

    // 12 edges
    [
        [A,B], [B,C], [C,D], [D,A],   // front face
        [E,F], [F,G], [G,H], [H,E],   // back face
        [A,E], [B,F], [C,G], [D,H]    // connectors
    ].forEach(edge => line(edge[0].x, edge[0].y, edge[1].x, edge[1].y));
}

// --------------------------------------------------
// List of cube positions
let cubePositions = [
    {x:-80, y:20},
    {x:-20, y:20},
    {x: 40, y:20},
    {x:100, y:20}
];

// --------------------------------------------------
// Iterate once per frame
let idx = 0;

function walk() {
    if (idx < cubePositions.length) {
        let p = cubePositions[idx];
        drawCube(p.x, p.y);
        idx++;
        return true;
    }
    return false;
}