helpers.js

;(function(m)
{
    m.abs       = function(n)
    { return n > 0 ? n : -n; };

    m.clamp     = function(n, min, max)
    { return n < min ? min : n > max ? max : n; };

    m.lerp      = function(n, n1, n2)
    { return (n1 * (1 - n)) + (n2 * n); };

    m.normalize = function (n, min, max)
    { return (n - min) / (max - min); };

    m.between   = function(n, min, max)
    { return (min <= n) && (n <= max); };

    m.map       = function(n, min1, max1, min2, max2)
    { return m.lerp(m.normalize(m.clamp(n, min1, max1), min1, max1), min2, max2); };

    m.loop      = function loop(n, min, max)
    {
        var p = m.floor(max - min + 1),
            q = (n - min) % p;

        if(q < 0) { q += p; }

        return min + q;
    };

    m.round     = function(n)
    { return (n + 0.5) | 0; };

    var a = [1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000, 10000000000];
    m.trunc     = function(n, d)
    {
        d = m.clamp(d, 0, 10);
        return m.round(n * a[d]) / a[d];
    };
})(Math)