Strange Crystals Deobfuscation Attempt

var canvas = document.getElementsByTagName('canvas')[0];
var context = canvas.getContext('2d');

document.body.bgColor = X = Y = H = I = J = E = Q = U = V = 0;
T = [l = 1];
C = (canvas.width = canvas.height = innerHeight) / 2;

setInterval(function() {
    for (i = H; i < X + 1400; H = ++i) {
        s = i % 800;
        if (!s) {
            /* Will run every once in a while to change direction and environment */
            changeCounter = i / 800;
            inclineAmount = changeCounter & 1 && -Q + (Q = Math.random() > 0.5); // Centered around 0.
            turnAmount = !inclineAmount && changeCounter && (turnAmount + 2 + (Math.random() > 0.5)) % 3 - 1; //Centered around 0.
            inStalCave = !inclineAmount && changeCounter > 9 && !inStalCave && Math.random() > 0.7; //Boolean.
            W = 1.8 * Math.random() - 1;
        }

        F = (s < 160) - (s > 639);
        E += F;

        T[i % 1400] = [I += J, J += turnAmount, U += V, V = inclineAmount * E, !inclineAmount && Math.exp(-(L = i % 400 - 200) * L / 3000) / 1.5, i % 400, Math.random() > 0.95];
        rectData = T[i % 1400];

        if (!(i % 10)) {
            Z = 9.8 + inStalCave * E / 15;
            y = Z
            z = W * inStalCave * E / 15;


            /*
                Rect info is stored in array rectData in the following order and repeated as many times as needed:
                - X position (relative to centre)
                - Init color (from white to black)
                - Width from x
                - Y position (relative to centre)
                - Height from y
            */


            /* Cave (literally just a circle) */
            for (g = Math.random() / 6; g < 6.3; g += 2 / Z) {
                if (inclineAmount || inStalCave) {
                    if (Math.random() > 0.4) {
                        rectData.push(1.1 * Z * Math.cos(g + 11));
                        rectData.push(7 + inStalCave * 16, 4 - F);
                        rectData.push(Z * Math.cos(g) + 2 + z);
                        rectData.push(4 - F);
                    }
                } else {
                    if (Math.random() > (Math.cos(g) > 0.5)) {
                        rectData.push(1.1 * Z * Math.cos(g + 11));
                        rectData.push(7 + inStalCave * 16);
                        rectData.push(4 - F, Z * Math.cos(g) + 2 + z);
                        rectData.push(4 - F);
                    }
                }
            }

            t = 2 * Z * Math.random() - Z;
            w = t * t * Math.random() / 6;

            /* Stalactites and Stalagmites */
            while (inStalCave * w > 0.2) {
                rectData.push(t);
                rectData.push(7 + inStalCave * 16);
                rectData.push(w);
                rectData.push(--y + z);
                rectData.push(1.1);

                rectData.push(t);
                rectData.push(7 + inStalCave * 16);
                rectData.push(w *= 0.8);
                rectData.push(-y + z);
                rectData.push(1.1);
            }

            /* I have no clue what this is */
            if (!Q && (inStalCave * W > 0.6)) {
                rectData.push(2 * Z * Math.random() - Z);
                rectData.push(12);
                rectData.push(0.2);
                rectData.push(Z * Math.random() - Z / 2 + z);
                rectData.push(1 + Math.random());
            }

            /*  */
            if (inStalCave && i % 20) {
                rectData.push(-2);
                rectData.push(22);
                rectData.push(0.5);
                rectData.push(-7);
                rectData.push(Z - 8 - z);

                rectData.push(2);
                rectData.push(22);
                rectData.push(0.5);
                rectData.push(-7);
                rectData.push(Z - 8 - z);
            }

            /* Horizontal bars on tracks */
            if (!(i % 20)) {
                rectData.push(0);
                rectData.push(6);
                rectData.push(6);
                rectData.push(-6.8);
                rectData.push(0.8);
            }

            /* Lamps */
            if (!L) {
                rectData.push(0);
                rectData.push(7 + inStalCave * 16);
                rectData.push(0.2);
                rectData.push(Z + z);
                rectData.push(Z + z - 5);

                rectData.push(0);
                rectData.push(7);
                rectData.push(0.6);
                rectData.push(5);
                rectData.push(0.6);
            }

            /* Doorway thing */
            if (!inclineAmount && !inStalCave) {
                if (!(i % 40)) {
                    rectData.push(-6);
                    rectData.push(6);
                    rectData.push(1.5);
                    rectData.push(5);
                    rectData.push(14);

                    rectData.push(6);
                    rectData.push(6);
                    rectData.push(1.5);
                    rectData.push(5);
                    rectData.push(14);
                }
                if (!(i % 20)) {
                    rectData.push(0);
                    rectData.push(6);
                    rectData.push(17);
                    rectData.push(8);
                    rectData.push(3);
                }
            }
        }

        /* Train track (the metal part) */
        if (!(i % 5)) {
            /* Left */
            rectData.push(-2);
            rectData.push(6);
            rectData.push(0.5);
            rectData.push(-6.5);
            rectData.push(0.6);

            /* Right */
            rectData.push(2);
            rectData.push(6);
            rectData.push(0.5);
            rectData.push(-6.5);
            rectData.push(0.6);
        }
    }
    q = T[X % 1400];
    while (true) {
        d = --i - X;
        if (!d)
            break;
        rectData = T[i % 1400];
        f = C / (d / 10 + 3);
        v = g = 0;
        t = C + f * (rectData[g] - q[g++] - d * q[g++]) / 3000;
        u = C + f * (rectData[g] - q[g++] - d * q[g++]) / 3000;

        /* Light flicker. */
        x = rectData[g++];
        if (rectData[g++])
            l = g++ && l;
        else if (rectData[g++])
            l =  Math.random() > 0.3;
        else
            l = 1;
        x *= l;

        y = d / 1800;
        while (true) {
            z = f * rectData[g++];
            w = rectData[g++];
            if (!w)
                break;

            v != w && (v = w, context.fillStyle = 'hsl(0,0%,' + 16 * (w & 7) * (w & 8 || y + x * (w < 16)) + '%)');

            var rectX = t + z - (z = f * rectData[g++]) / 2;
            var rectY = u - f * rectData[g++] + (w == 12 && f * 6 * Math.cos(g + X / 400));
            var rectW = z;
            var rectH = f * rectData[g++];

            context.fillRect(rectX, rectY, rectW, rectH);
        }
    }
    Y += 4 - 3 * Math.exp(-X / 400) + q[2] / 30000;
    X = 0 | Y;
}, 35);