The velocity at point z in the complex plane is proportional to z^2 - z + c for a constant c.
Created
August 4, 2013 19:39
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Flow experiment II
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <title>Spiral flow</title> | |
| <script src="http://bl.ocks.org/robinhouston/raw/6096562/rAF.js" charset="utf-8"></script> | |
| <script src="http://bl.ocks.org/robinhouston/raw/6151172/streamer.js" charset="utf-8"></script> | |
| <style> | |
| canvas { background-color: #4C4C4C; } | |
| </style> | |
| <canvas width=960 height=500></canvas> | |
| <script> | |
| var NUM_STREAMS = 8000, | |
| MAX_AGE = 30, | |
| FADE_RATE = 0.05, | |
| BORDER = 100; | |
| var canvas = document.getElementsByTagName("canvas")[0], | |
| cx = canvas.getContext("2d"), | |
| streamer = Streamer({ | |
| canvas: canvas, | |
| num_streams: NUM_STREAMS, | |
| max_age: MAX_AGE, | |
| fade_rate: FADE_RATE, | |
| border: BORDER, | |
| velocity: to_px(10, julia(0, 10)) | |
| }); | |
| cx.strokeStyle = "rgba(255,255,255,0.1)"; | |
| cx.fillStyle = "rgba(255,255,255,0.05)"; | |
| cx.fillRect(0, 0, canvas.width, canvas.height); | |
| streamer.start(); | |
| // * Vector field transformers | |
| // Transform a vector field from origin-centred coordinates to pixel coords | |
| function to_px(n, f) { | |
| return function(x_px, y_px, t) { | |
| var divisor = Math.min(canvas.width, canvas.height)/n, | |
| x = (x_px - canvas.width/2) / divisor, | |
| y = (y_px - canvas.height/2) / divisor; | |
| var v = f(x, y, t); | |
| return v; | |
| }; | |
| } | |
| // * Primitive vector fields | |
| function julia(dx, dy) { | |
| return function(x, y, t) { | |
| return [ | |
| (x*x - y*y + dx - x), | |
| ( 2*x*y + dy - y) | |
| ]; | |
| } | |
| } | |
| </script> |
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