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lindenmayer.js
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lindenmayer.js
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var Lindenmayer = (function() {
var ANTICLOCK = '+';
var CLOCKWISE = '-';
var PUSH = '[';
var POP = ']';
var DRAW = 'F';
var RAD = Math.PI / 180;
function Pen(x, y, d, c) {
this.x = x;
this.y = y;
this.angle = d;
this.color = c || 'rgb(0,0,0)';
}
function LSystem(conf) {
var _tree = conf.seed;
var _angle = conf.angle;
var _rules = conf.rules;
var _constants = conf.constants || [DRAW];
var _canvas = conf.canvas;
var _context = conf.canvas.getContext('2d');
var _width = conf.width || _canvas.width;
var _height = conf.height || _canvas.height;
var _boundingBox = {
minX: 0,
minY: 0,
maxX: _width,
maxY: _height
};
var _pen;
var _originX = conf.x || 0;
var _originY = conf.y || 0;
var _initialAngle = conf.initialAngle || 0;
var _color = conf.color;
// Private
var process = function(dist, draw) {
var penStack = [];
for (var i = 0; i < _tree.length; i++) {
switch (_tree.charAt(i)) {
case ANTICLOCK:
_pen.angle += _angle;
break;
case CLOCKWISE:
_pen.angle -= _angle;
break;
case PUSH:
penStack.push(new Pen(_pen.x, _pen.y, _pen.angle, _pen.color));
break;
case POP:
_pen = penStack.pop();
break;
default:
drawForward(dist, draw);
break;
}
}
};
var drawForward = function(dist, draw) {
var lastX = _pen.x;
var lastY = _pen.y;
var angle = _pen.angle * RAD;
_pen.x += dist * Math.cos(angle);
_pen.y += dist * Math.sin(angle);
if (draw) {
_context.beginPath();
_context.moveTo(lastX, lastY);
_context.lineTo(_pen.x, _pen.y);
_context.strokeStyle = _pen.color;
_context.closePath();
_context.stroke();
} else {
if (_pen.x < _boundingBox.minX) {
_boundingBox.minX = _pen.x;
} else if (_pen.x > _boundingBox.maxX) {
_boundingBox.maxX = _pen.x;
}
if (_pen.y < _boundingBox.minY) {
_boundingBox.minY = _pen.y;
} else if (_pen.y > _boundingBox.maxY) {
_boundingBox.maxY = _pen.y;
}
}
};
var calculateDistance = function(oldDistance) {
var newDistX = (_width / (_boundingBox.maxX - _boundingBox.minX)) * oldDistance;
var newDistY = (_height / (_boundingBox.maxY - _boundingBox.minY)) * oldDistance;
return newDistX < newDistY ? newDistX : newDistY;
};
var calculateOffset = function(newDist, oldDist) {
_boundingBox.minX *= (newDist / oldDist);
_boundingBox.maxX *= (newDist / oldDist);
_boundingBox.minY *= (newDist / oldDist);
_boundingBox.maxY *= (newDist / oldDist);
return {
x: (_width / 2) - (((_boundingBox.maxX - _boundingBox.minX) / 2) + _boundingBox.minX),
y: (_height / 2) - (((_boundingBox.maxY - _boundingBox.minY) / 2) + _boundingBox.minY)
};
};
// Public
this.getTree = function() {
return _tree;
};
this.addConstants = function(c) {
_constants = _constants.concat(c);
};
this.iterate = function(iterations) {
var node;
var it = iterations || 1;
for (var i = 0; i < it; i++) {
var newTree = '';
for (var j = 0; j < _tree.length; j++) {
node = _tree.charAt(j);
newTree += _rules[node] || node;
}
_tree = newTree;
}
return _tree;
};
this.render = function() {
// Cleanup unused commands in tree
var reg = new RegExp('[^' + _constants.join('') + '\\+\\-\\[\\]]', 'g');
_tree = _tree.replace(reg, '');
// First Pass
var defaultDist = Math.max(_width, _height);
_pen = new Pen(0, 0, _initialAngle, _color);
process(defaultDist, false);
// Second Pass
var newDist = calculateDistance(defaultDist);
var offset = calculateOffset(newDist, defaultDist);
_pen = new Pen(_originX + offset.x, _originY + offset.y, _initialAngle, _color);
process(newDist, true);
};
}
var createLSystem = function(conf) {
return new LSystem(conf);
};
return {
createLSystem: createLSystem
};
})();