PolyGravity JS - level loader

/** loadLevel(data:Array): Level
 * Loads level (set of shapes with bound Canvases) from an array.
 */
function loadLevel(d) {
    var L, o, q, i, n, p = 5, l = d.length, vx, vy, qx, qy;
    L = { };
    L.c = d.slice(0, 5); // get level colours from data
    L.o = []; // shapes in level
    L.l = []; // lines in level
    // sample player values:
    P = { x: 100, y: -200, r: 16, vd: hpi, vv: 0, vx: 0, vy: 0, va: 0.7, vf: 0.3, vm: 5 };
    while (p < l) {
        switch (v()) {
        case 1:
            o = {
                c: v(), // color index
                d: v(), // depth
                t: v(), // type
                n: v(), x: [], y: [], d: [] // vertexes
            };
            // skip first two values (not used)
            v(); v();
            // initial bounds (set to min/max integer values):
            o.L = o.T = 0x7FFFFFFF;
            o.R = o.B = -0x7FFFFFFF;
            // load points into shape:
            n = o.n;
            for (i = 1; i < n; i++) {
                // bounds:
                o.L = min(o.L, vx = v());
                o.T = min(o.T, vy = v());
                o.R = max(o.R, vx);
                o.B = max(o.B, vy);
                o.x.push(vx);
                o.y.push(vy);
            }
            // re-add first points for easier iterating:
            o.x.push(o.x[0]);
            o.y.push(o.y[0]);
            // extend bounding box a bit:
            o.L -= 5; o.R += 5; o.T -= 5; o.B += 5;
            // create canvas for shape:
            q = (o.g = cn(o.R - o.L, o.B - o.T)).c;
            // debugging: draw bounding box of shape
            q.strokeStyle = o.t == 1 ? 'blue' : o.t == 2 ? 'red' : o.t == 3 ? 'yellow' : 'white';
            q.strokeRect(0, 0, o.g.width, o.g.height);
            // draw shape in canvas:
            q.fillStyle = hexc(L.c[o.c]);
            // draw shape into it's canvas:
            q.moveTo(o.x[0], o.y[0]);
            q.beginPath();
            for (i = 0; i < n; i++) {
                vx = o.x[i]; qx = o.x[i + 1];
                vy = o.y[i]; qy = o.y[i + 1];
                if (i) q.lineTo(vx - o.L, vy - o.T);
                o.d.push([vx, vy, qx, qy, atan2(qy - vy, qx - vx)]);
            }
            q.closePath();
            q.fill();
            q.stroke();
            // push shape into level list
            L.o.push(o);
            break;
        }
    }
    return L;
    // inner function, returns next data element
    function v() { return d[p++] }
}