(click to reload)
A fork of Mike Bostock's branched random walk. The code has been refactored to allow a pen up/down operation, model was paramaterized further, and three variants with slightly different model settings are shown.
-
-
Save dribnet/9243c66a8549b31e047c9ea322901149 to your computer and use it in GitHub Desktop.
Branched Random Walks
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| license: gpl-3.0 |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| /* this is my general purpose random function | |
| * | |
| * random numbers are always paramaterized between min and max. | |
| * however, the "focus" variable allows an interpolation between | |
| * a uniform and gaussian distribution (normal extends | |
| * "focus" standard deviations from center and a focus of 0 | |
| * is a uniform distribution). | |
| */ | |
| function focusedRandom(min, max, focus, mean) { | |
| if(max === undefined) { | |
| max = min; | |
| min = 0; | |
| } | |
| if(focus === undefined) { | |
| focus = 1.0; | |
| } | |
| if(mean === undefined) { | |
| mean = (min + max) / 2.0; | |
| } | |
| if(focus == 0) { | |
| return d3.randomUniform(min, max)(); | |
| } | |
| else if(focus < 0) { | |
| focus = -1 / focus; | |
| } | |
| sigma = (0.5 * (max - min)) / focus; | |
| val = d3.randomNormal(mean, sigma)(); | |
| if (val > min && val < max) { | |
| return val; | |
| } | |
| return d3.randomUniform(min, max)(); | |
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <canvas width="960" height="500"></canvas> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script language="javascript" type="text/javascript" src="focusedRandom.js"></script> | |
| <script> | |
| var canvas = document.querySelector("canvas"), | |
| context = canvas.getContext("2d"), | |
| width = canvas.width, | |
| height = canvas.height, | |
| tail_y = [0.2 * canvas.height, 0.5 * canvas.height, 0.8 * canvas.height], | |
| randomY = d3.randomNormal(0,1.5), | |
| randomPenToUp = d3.randomUniform(-15, 1), | |
| randomPenToDown = d3.randomUniform(-5, 1); | |
| render(); | |
| canvas.onclick = render; | |
| function render() { | |
| context.clearRect(0, 0, width, height); | |
| render_tail(0); | |
| render_tail(1); | |
| render_tail(2); | |
| } | |
| function render_tail(which_tail) { | |
| var length = Math.floor(focusedRandom(80, 1200, 2, 900)); | |
| var tail_length = Math.floor(focusedRandom(60, 400, 3, 200)); | |
| var tail_every = Math.floor(focusedRandom(1, 30, 4, 4)); | |
| var color = d3.scaleSequential(d3.interpolateRainbow).domain([0, length]); | |
| var x_bias = 600 / length; | |
| var local_randomX = d3.randomNormal(x_bias,2); | |
| var x0 = width / 20, | |
| y0 = tail_y[which_tail], | |
| pen_up0 = false, | |
| tail_chunk = Math.floor(tail_length / 20), | |
| mainWalk = randomWalk([[x0, y0, pen_up0, null]], length, local_randomX); | |
| context.lineJoin = "round"; | |
| context.lineCap = "round"; | |
| context.lineWidth = 1.5; | |
| context.strokeStyle = "black"; | |
| renderWalk(mainWalk); | |
| context.globalCompositeOperation = "multiply"; | |
| context.lineWidth = 1; | |
| for (var i = tail_every; i < mainWalk.length; i += tail_every) { | |
| var branchHistory = mainWalk.slice(0, i+1) | |
| for (var j = 0; j < 1; ++j) { | |
| context.strokeStyle = color(i); | |
| branchCopy = branchHistory.slice(); | |
| for (var k = 0, m = 20; k < m; ++k) { | |
| context.globalAlpha = (m - k - 1) / m; | |
| var pieceWalk = randomWalk(branchCopy, tail_chunk, local_randomX), | |
| pieceEnd = pieceWalk[pieceWalk.length - 1]; | |
| renderWalk(pieceWalk); | |
| branchCopy.push(pieceEnd) | |
| } | |
| context.globalAlpha = 1; | |
| } | |
| } | |
| } | |
| function renderWalk(walk) { | |
| var i, n = walk.length; | |
| context.beginPath(); | |
| context.moveTo(walk[0][0], walk[0][1]); | |
| for (i = 0; i < n; ++i) { | |
| // check for pen_up | |
| if(walk[i][2]) { | |
| context.moveTo(walk[i][0], walk[i][1]); | |
| } | |
| else { | |
| context.lineTo(walk[i][0], walk[i][1]); | |
| } | |
| } | |
| context.stroke(); | |
| } | |
| function randomWalk(history, n, local_randomX) { | |
| var points, i, x, y, pen_up, randomPenFn; | |
| points = new Array(n); | |
| points[0] = history[history.length - 1]; | |
| [x, y, pen_up] = points[0]; | |
| for (i = 1; i < n; ++i) { | |
| randomPenFn = pen_up ? randomPenToDown : randomPenToUp; | |
| points[i] = [ | |
| x += local_randomX(), | |
| y += randomY(), | |
| pen_up ^= (randomPenFn() > 0) | |
| ]; | |
| } | |
| return points; | |
| } | |
| </script> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment