interpolate_bezier

interpolate_bezier.js

function interpolate_bezier(a, b, c, d, resolution) {
    /* Blender's forward differencing bezier interpolation */

    var p = [];
    var res = resolution - 1;
    var dims = Math.max(
        a.length, b.length, c.length, d.length);

    for (var i = 0; i < res; i++) {
        var x = [];
        for (var j = 0; j < dims; j++)
            x.push(0.0);
        p.push(x);
    }

    for (var i = 0; i < dims; i++) {
        var q0, q1, q2, q3;
        var rt0, rt1, rt3, f;
        var f;

        q0 = a[i];
        q1 = b[i];
        q2 = c[i];
        q3 = d[i];
        f = res;
        rt0 = q0;
        rt1 = 3.0 * (q1 - q0) / f;
        f *= f;
        rt2 = 3.0 * (q0 - 2.0 * q1 + q2) / f;
        f *= res;
        rt3 = (q3 - q0 + 3.0 * (q1 - q2)) / f;
        q0 = rt0;
        q1 = rt1 + rt2 + rt3;
        q2 = 2 * rt2 + 6 * rt3;
        q3 = 6 * rt3;

        for (var j = 0; j < res; j++) {
            p[j][i] = q0;
            q0 += q1;
            q1 += q2;
            q2 += q3;
        }
    }

    return p;
}