/Play/play.js

function getRGB(r, g, b) {
    return r << 24 | g << 16 | b;
}

function drawLine(screen, x0, y0, x1, y1) {
    var dx = Math.abs(x1 - x0), sx = x0 < x1 ? 1 : -1;
    var dy = Math.abs(y1 - y0), sy = y0 < y1 ? 1 : -1;
    var err = (dx > dy ? dx : -dy) / 2;

    while (true) {
        screen.setPixel(x0, y0, 200, 200, 200);
        if (x0 === x1 && y0 === y1)
            break;
        var e2 = err;
        if (e2 > -dx) {
            err -= dy;
            x0 += sx;
        }
        if (e2 < dy) {
            err += dx;
            y0 += sy;
        }
    }
}

var lastTime = new Date();

var frame = 0;

function paint(buffer, width, height, pitch, bpp) {
    var uint32View = new Uint32Array(buffer);

    var screen = {
        setPixel : function(x, y, r, g, b) {
            uint32View[(y * pitch / bpp) + x] = getRGB(r, g, b);
        }
    }

    frame += 10;

    for (y = 0; y < height; y++) {
        start = y * pitch / bpp;
        for (x = 0; x < width; x++) {
            uint32View[start + x] = getRGB((x * x) / 256 + 3 * y + frame,
                    (y * y) / 256 + x + frame, frame);
        }
    }

    if (false) {
        x0 = Math.round((Math.random() * width));
        x1 = Math.round((Math.random() * width));
        y0 = Math.round((Math.random() * height));
        y1 = Math.round((Math.random() * height));
        drawLine(screen, x0, x1, y0, y1);
    }

    newTime = new Date()
    if (frame % 100 == 0) {
        print("Frame Rate (fps): "
                + (1000 / (newTime.getTime() - lastTime.getTime()) + "\n"))
    }
    lastTime = newTime;
}