path_from_function_2

_.md

Gist #4423022 [ Launch Inlet ]
Gist #4421006 [ Launch Inlet ]
Gist #4420916 [ Launch Inlet ]
Gist #4420154 [ Launch Inlet ]
Gist #4420141 [ Launch Inlet ]
Gist #3200444

config.json

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inlet.js

var svg = d3.select("svg");

// paths visit http://www.w3.org/TR/SVG11/paths.html


// variables
var bend = 60,							// angle to twist (degrees)
    iterations = Math.floor(4.15263),	// number of rewrites
	F = 260/(Math.pow(3,iterations)),	// arm distance
	angle_offset = to_rad(bend),		// angle as radian
    angle_rad = 0,                  	// the current angle for drawing
    x_start = 33,                   	// drawing start x
    y_start = 150,                  	// drawing start y
    rules = {};                     	// a map of the rules

// converting from resulting string to svg path commands ---------------

function to_rad(degrees){
  return degrees * (2*Math.PI) / 360
}

function get_xy(angle_rad){
  return {x: Math.cos(angle_rad) * F,
          y: Math.sin(angle_rad) * F}
}

function command_from_rad(angle_rad){
  var c = get_xy(angle_rad);
  return " l " + c.x + " " + c.y
}

function make_path(rules, start_string){
  return "M " + x_start + "," + y_start + recursive_path(rules,start_string, 0);
}

function recursive_path(rules, input_string, iteration) {
  var token = "";
  var path_string = "";

  for (i in d3.range(input_string.length)) {
      token = input_string[i];
      if (token === '-') angle_rad += angle_offset;
      else if (token === '+') angle_rad -= angle_offset;
      else if (token in rules) {
        // if we're at the bottom level, move forward
        if (iteration >= iterations) path_string += command_from_rad(angle_rad);
        // else go deeper down the rabbit hole...
        else path_string += recursive_path(rules, rules[token], iteration+1);
     }
  }
  return path_string;
}

function draw_path(path){  
  svg.append("path")
    .attr("d", path)
    .style("fill", "none")
    .style("stroke", "#0033FF")
    .style("stroke-width", 1)
}

rules["F"] = "F+G--F+F";
rules["G"] = "F---F+F";
start      = "F";

var path = 	make_path(rules, start);
//var path = 	make_path("F+F--F+F+F+F--F+F--F+F--F+F+F+F--F+F+F+F--F+F+F+F--F+F--F+F--F+F+F+F--F+F--F+F--F+F+F+F--F+F--F+F--F+F+F+F--F+F+F+F--F+F+F+F--F+F--F+F--F+F+F+F--F+F")
draw_path(path)