An improvement upon the previous experiment. Two alternating concatenation rules (X and Y) are used to make the spiral grow alternatively clockwise and counterclockwise. Due to the fact that less segments are aligned, the worst aspect ratio of this layout is 1/4 like for the Hilbert spiral layout (the former experiment gave 1/6).
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FASS spiral II (L-system)
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| `// noprotect` | |
| ### compute a Lindenmayer system given an axiom, a number of steps and rules ### | |
| fractalize = (config) -> | |
| input = config.axiom | |
| for i in [0...config.steps] | |
| output = '' | |
| for char in input | |
| if char of config.rules | |
| output += config.rules[char] | |
| else | |
| output += char | |
| input = output | |
| return output | |
| ### convert a Lindenmayer string into an SVG path string ### | |
| svg_path = (config) -> | |
| angle = 0.0 | |
| path = 'M0 0' | |
| for char in config.fractal | |
| if char == '+' | |
| angle += config.angle | |
| else if char == '-' | |
| angle -= config.angle | |
| else if char == 'F' | |
| path += "l#{config.side * Math.cos(angle)} #{config.side * Math.sin(angle)}" | |
| return path | |
| ### animate the path ### | |
| ### from Mike Bostock's stroke dash interpolation example http://bl.ocks.org/mbostock/5649592 ### | |
| tweenDash = () -> | |
| l = this.getTotalLength() | |
| i = d3.interpolateString('0,' + l, l + ',' + l) | |
| return (t) -> i(t) | |
| transition = (path) -> | |
| path.transition() | |
| .duration(20000) | |
| .attrTween('stroke-dasharray', tweenDash) | |
| curve = fractalize | |
| axiom: 'FX' | |
| steps: 4 | |
| rules: | |
| X: 'Y-LFL-FRF-LFLFL-FRFR+F' | |
| Y: 'X+RFR+FLF+RFRFR+FLFL-F' | |
| L: 'LF+RFR+FL-F-LFLFL-FRFR+' | |
| R: '-LFLF+RFRFR+F+RF-LFL-FR' | |
| d = svg_path | |
| fractal: curve | |
| side: 5 | |
| angle: Math.PI/2 | |
| width = 960 | |
| height = 500 | |
| vis = d3.select('body').append('svg') | |
| .attr | |
| width: width | |
| height: height | |
| .append('g') | |
| .attr | |
| transform: "translate(#{width/2},#{height/2})" | |
| vis.append('path') | |
| .attr('class', 'curve shadow') | |
| .attr('d', d) | |
| vis.append('path') | |
| .attr('class', 'curve') | |
| .attr('d', d) | |
| .call(transition) | |
| vis.append('circle') | |
| .attr | |
| r: 2 | |
| fill: 'red' | |
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| svg { | |
| background: white; | |
| } | |
| .curve { | |
| fill: none; | |
| stroke: black; | |
| stroke-width: 1px; | |
| shape-rendering: crispEdges; | |
| } | |
| .shadow { | |
| opacity: 0.1; | |
| } |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta name="description" content="FASS spiral II (L-system)" /> | |
| <title>FASS spiral II (L-system)</title> | |
| <link rel="stylesheet" href="index.css"> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| </head> | |
| <body> | |
| <script src="index.js"></script> | |
| </body> | |
| </html> |
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| (function() { | |
| // noprotect; | |
| /* compute a Lindenmayer system given an axiom, a number of steps and rules | |
| */ | |
| var curve, d, fractalize, height, svg_path, transition, tweenDash, vis, width; | |
| fractalize = function(config) { | |
| var char, i, input, output, _i, _j, _len, _ref; | |
| input = config.axiom; | |
| for (i = _i = 0, _ref = config.steps; 0 <= _ref ? _i < _ref : _i > _ref; i = 0 <= _ref ? ++_i : --_i) { | |
| output = ''; | |
| for (_j = 0, _len = input.length; _j < _len; _j++) { | |
| char = input[_j]; | |
| if (char in config.rules) { | |
| output += config.rules[char]; | |
| } else { | |
| output += char; | |
| } | |
| } | |
| input = output; | |
| } | |
| return output; | |
| }; | |
| /* convert a Lindenmayer string into an SVG path string | |
| */ | |
| svg_path = function(config) { | |
| var angle, char, path, _i, _len, _ref; | |
| angle = 0.0; | |
| path = 'M0 0'; | |
| _ref = config.fractal; | |
| for (_i = 0, _len = _ref.length; _i < _len; _i++) { | |
| char = _ref[_i]; | |
| if (char === '+') { | |
| angle += config.angle; | |
| } else if (char === '-') { | |
| angle -= config.angle; | |
| } else if (char === 'F') { | |
| path += "l" + (config.side * Math.cos(angle)) + " " + (config.side * Math.sin(angle)); | |
| } | |
| } | |
| return path; | |
| }; | |
| /* animate the path | |
| */ | |
| /* from Mike Bostock's stroke dash interpolation example http://bl.ocks.org/mbostock/5649592 | |
| */ | |
| tweenDash = function() { | |
| var i, l; | |
| l = this.getTotalLength(); | |
| i = d3.interpolateString('0,' + l, l + ',' + l); | |
| return function(t) { | |
| return i(t); | |
| }; | |
| }; | |
| transition = function(path) { | |
| return path.transition().duration(20000).attrTween('stroke-dasharray', tweenDash); | |
| }; | |
| curve = fractalize({ | |
| axiom: 'FX', | |
| steps: 4, | |
| rules: { | |
| X: 'Y-LFL-FRF-LFLFL-FRFR+F', | |
| Y: 'X+RFR+FLF+RFRFR+FLFL-F', | |
| L: 'LF+RFR+FL-F-LFLFL-FRFR+', | |
| R: '-LFLF+RFRFR+F+RF-LFL-FR' | |
| } | |
| }); | |
| d = svg_path({ | |
| fractal: curve, | |
| side: 5, | |
| angle: Math.PI / 2 | |
| }); | |
| width = 960; | |
| height = 500; | |
| vis = d3.select('body').append('svg').attr({ | |
| width: width, | |
| height: height | |
| }).append('g').attr({ | |
| transform: "translate(" + (width / 2) + "," + (height / 2) + ")" | |
| }); | |
| vis.append('path').attr('class', 'curve shadow').attr('d', d); | |
| vis.append('path').attr('class', 'curve').attr('d', d).call(transition); | |
| vis.append('circle').attr({ | |
| r: 2, | |
| fill: 'red' | |
| }); | |
| }).call(this); |
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