path_from_function_2

_.md

Gist #4429562
Gist #4429521
Gist #4429490
Gist #4429395
Gist #4428230 [ Launch Inlet ]
Gist #4428214
Gist #4425078
Gist #4425074
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

// variables
var bend = 120,                              // angle to twist (degrees)
    i_max = 10,								// limit, warning 10 is probably an upperlimit
    i_user = Math.abs(Math.floor(10)),		// scrub between 1 and upperlimit for recursion levels
    iterations = Math.min(i_max, i_user),	// number of rewrites (recursion levels in grammar)
	F = 1040/(Math.pow(1.5,iterations)),		// arm distance
	angle_offset = to_rad(bend),			// angle as radian
    angle_rad = 0,                  		// the current angle for drawing
    x_start = 154,                   		// drawing start x
    y_start = 372,                  		// drawing start y
    x_current = x_start,                    // current cursor position x
    y_current = y_start,                    // current cursor position y
    rules = {},                     		// a map of the rules
    commands = {};                          // a map of the commands

/* Helper Functions */

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

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

function command_from_rad(command, angle_rad){
  var command_parts = command.split(" ");
  Lv = parseFloat(command_parts[1]);
  if (command_parts.length > 2) {
    if (command_parts[2] == "R") Lv = Lv*(1 + (command_parts[3] * (Math.random() - 0.5))/100);
  }
  var c = get_xy(angle_rad,Lv);
  x_current = x_current + c.x;
  y_current = y_current + c.y;
  if (command_parts[0] == "L") tributary.ctx.lineTo(x_current, y_current);
  if (command_parts[0] == "M") {
    tributary.ctx.stroke();
    tributary.ctx.moveTo(x_current, y_current);
  }
}

function make_path(rules, commands, start_string){
  tributary.ctx.moveTo(x_start,y_start);
  tributary.ctx.strokeStyle = '#000AFF';
  tributary.ctx.lineWidth = 2;
  recursive_path(rules,commands,start_string, 0);
  tributary.ctx.stroke();
}

/* L-systems grammar rewriting */
function recursive_path(rules, commands, input_string, iteration) {
  var token = "";

  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) command_from_rad("L " + F, angle_rad);
        // else go deeper down the rabbit hole...
        else recursive_path(rules, commands, rules[token], iteration+1);
      }
      else if (token in commands) {
        command_from_rad(commands[token], angle_rad);
      } 
  }
}

delete rules;
delete commands;

// The rules: 
// + means turn left by bend degrees
// - means turn right by bend degrees
// Variables (like A or B) get replaced by the rule when encountered
// This keeps repeating until the maximum number of iterations is reached
// You need one rule entry per variable used
rules["X"] = "X+YF";
rules["Y"] = "FX-Y";

// The commands:
// "Lnn" means draw a line of length nn, e.g. L90 means draw a line 90 pixels long
// "Mnn" means move nn pixels forward, e.g. M90 means move the current cursor 90 pixels forward
// "RAnn" at the end of the command means add 
commands["F"] = "L " + F + " R " + 20;

start = "FY";

make_path(rules, commands, start);
    
/* EOF */