propagation.js

(function (exports) {

    function propagate(arr) {
        arr.sort(function (x, y) {
            return x.nr - y.nr;
        });
        var linregs = [];
        for (var j = 0; j < 11; j++)
            linregs.push(new LinReg());
        var count = 0;
        arr.forEach(function (item) {
            if (item.anchoring) {
                var w = item.anchoring;
                for (var j = 0; j < 3; j++)
                    w[j] += (w[j + 3] + w[j + 6]) / 2;
                w.push(normalize(w, 3) / item.width, normalize(w, 6) / item.height);
                for (var j = 0; j < w.length; j++)
                    linregs[j].add(item.nr, w[j]);
                count++;
            }
        });
        if (count >= 2) {
            var len = arr.length;
            if (!arr[0].anchoring) {
                var nr = arr[0].nr;
                var w = [];
                for (var j = 0; j < linregs.length; j++)
                    w.push(linregs[j].get(nr));
                orthonormalize(w);
                arr[0].anchoring = w;
                count++;
            }
            if (!arr[len - 1].anchoring) {
                var nr = arr[len - 1].nr;
                var w = [];
                for (var j = 0; j < linregs.length; j++)
                    w.push(linregs[j].get(nr));
                orthonormalize(w);
                arr[len - 1].anchoring = w;
                count++;
            }
            var start = 1;
            while (count < len) {
                while (arr[start].anchoring)
                    start++;
                var next = start + 1;
                while (!arr[next].anchoring)
                    next++;
                var pnr = arr[start - 1].nr;
                var nnr = arr[next].nr;
                var panch = arr[start - 1].anchoring;
                var nanch = arr[next].anchoring;
                var linints = [];
                for (var j = 0; j < panch.length; j++)
                    linints.push(new LinInt(pnr, panch[j], nnr, nanch[j]));
                for (var i = start; i < next; i++) {
                    var nr = arr[i].nr;
                    var anchoring = [];
                    for (var j = 0; j < linints.length; j++)
                        anchoring.push(linints[j].get(nr));
                    arr[i].anchoring = anchoring;
                    count++;
                }
                start = next + 1;
            }
        }
        arr.forEach(function (item) {
            var w = item.anchoring;
            orthonormalize(w);
            var v = w.pop();
            var u = w.pop();
            for (var i = 0; i < 3; i++) {
                w[i + 3] *= u * item.width;
                w[i + 6] *= v * item.height;
                w[i] -= (w[i + 3] + w[i + 6]) / 2;
            }
        });
    }

    function LinInt(x1, y1, x2, y2) {
        this.get = function (x) {
            return y1 + (y2 - y1) * (x - x1) / (x2 - x1);
        };
    }

    function LinReg() {
        var n = 0;
        var Sx = 0;
        var Sy = 0;
        var Sxx = 0;
        var Sxy = 0;
        var a, b;
        this.add = function (x, y) {
            n++;
            Sx += x;
            Sy += y;
            Sxx += x * x;
            Sxy += x * y;
            if (n >= 2) {
                b = (n * Sxy - Sx * Sy) / (n * Sxx - Sx * Sx);
                a = Sy / n - b * Sx / n;
            }
        };
        this.get = function (x) {
            return a + b * x;
        };
    }

    function normalize(arr, idx) {
        var len = 0;
        for (var i = 0; i < 3; i++)
            len += arr[idx + i] * arr[idx + i];
        len = Math.sqrt(len);
        for (var i = 0; i < 3; i++)
            arr[idx + i] /= len;
        return len;
    }

    function orthonormalize(arr) {
        normalize(arr, 3);
        var dot = 0;
        for (var i = 0; i < 3; i++)
            dot += arr[i + 3] * arr[i + 6];
        for (var i = 0; i < 3; i++)
            arr[i + 6] -= arr[i + 3] * dot;
        normalize(arr, 6);
    }

    exports.propagate = propagate;

})(typeof exports === "undefined" ? this["propagation"] = {} : exports);