1, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixels);
        return pixels;
    };
    function testPixel(blockList, allowList) {
        function testList(list, expected) {
            for (var n = 0; n < list.length; n++) {
                var l = list[n];
                var x = -Math.floor(l * canvas.width / 2) + canvas.width / 2;
                var y = -Math.floor(l * canvas.height / 2) + canvas.height / 2;
                var source = readLocation(x, y);
                if (Math.abs(source[0] - expected) > 2) {