Pythagoras tree in OpenJSCAD

PythagorasTree.js

//Experiment with rendering L-Systems in OpenJSCAD
// (see https://en.wikipedia.org/wiki/L-system#Example_2:_Pythagoras_tree)

//Production rules
var rules =
{
    "1": "11",
    "0": "1[0]0",
};

//One level of production
function proc(s)
{
    var r = "";
    s.split('').forEach(
        function(c)
        {
            r += rules[c] || c;
        }
    );
    return r;
}

//Run the production rules n times on string s
function doL(s, n)
{
    for(var i = 0; i < n; i++)
        s = proc(s);
    return s;
}

//OpenJSCAD main
function main()
{
    var cl = 2;  //cylinder length
    
    var o = [], tx = 0, ty = 0, tz = 0, ry = 0;
    var pos = [];
    var rot = [];
    var s = doL("0", 5);

    s.split('').forEach(
        function(c)
        {
            if(c == "1")
            {
              o.push(cylinder({r:1, h:cl}).rotateY(ry).translate([tx, ty, tz]));
              tz += cl * cos(ry);
              tx += cl * sin(ry);
            }
            else if(c == "[")
            {
                pos.push([tx, ty, tz]);
                rot.push(ry);
                ry -= 45;
            }
            else if(c == "]")
            {
                ry = rot.pop();
                t = pos.pop();
                tx = t[0]; ty = t[1]; tz = t[2];
                ry += 45;
            }
            else if(c == "0")
            {
                o.push(cylinder({r:1, h:cl}).rotateY(ry).translate([tx, ty, tz]));
                tz += cl * cos(ry);
                tx += cl * sin(ry);
                o.push(sphere({r:2, center:true}).translate([tx, ty, tz]));
            }
        }
    );
    
    return o;
}