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Sunflower
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<!-- Copyright 2011 the Dart project authors. All rights reserved. | |
Use of this source code is governed by a BSD-style license | |
that can be found in the LICENSE file. --> | |
<h2>Dr. Fibonacci's Sunflower Spectacular</h2> | |
<div> | |
<canvas id="canvas" width="300" height="300"></canvas> | |
</div> | |
<div> | |
<label>0</label> | |
<input id="slider" type="range" max="1000" value="500" /> | |
<label>1000</label> | |
</div> |
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// Copyright 2011 the Dart project authors. All rights reserved. | |
// Use of this source code is governed by a BSD-style license | |
// that can be found in the LICENSE file. | |
library sunflower; | |
import 'dart:html'; | |
import 'dart:math' as math; | |
void main() { | |
new Sunflower(); | |
} | |
class Sunflower { | |
static const String ORANGE = "orange"; | |
static const SEED_RADIUS = 2; | |
static const SCALE_FACTOR = 4; | |
static const TAU = math.pi * 2; | |
static const MAX_D = 300; | |
CanvasRenderingContext2D ctx; | |
num xc, yc; | |
num seeds = 0; | |
num PHI; | |
Sunflower() { | |
PHI = (math.sqrt(5) + 1) / 2; | |
CanvasElement canvas = querySelector("#canvas"); | |
xc = yc = MAX_D / 2; | |
ctx = canvas.getContext("2d"); | |
InputElement slider = querySelector("#slider"); | |
slider.onChange.listen((Event e) { | |
seeds = int.parse(slider.value); | |
drawFrame(); | |
}); | |
seeds = int.parse(slider.value); | |
drawFrame(); | |
} | |
// Draw the complete figure for the current number of seeds. | |
void drawFrame() { | |
print('seed value = ${seeds}'); | |
ctx.clearRect(0, 0, MAX_D, MAX_D); | |
for (var i = 0; i < seeds; i++) { | |
var theta = i * TAU / PHI; | |
var r = math.sqrt(i) * SCALE_FACTOR; | |
var x = xc + r * math.cos(theta); | |
var y = yc - r * math.sin(theta); | |
drawSeed(x, y); | |
} | |
} | |
// Draw a small circle representing a seed centered at (x,y). | |
void drawSeed(num x, num y) { | |
ctx.beginPath(); | |
ctx.lineWidth = 2; | |
ctx.fillStyle = ORANGE; | |
ctx.strokeStyle = ORANGE; | |
ctx.arc(x, y, SEED_RADIUS, 0, TAU, false); | |
ctx.fill(); | |
ctx.closePath(); | |
ctx.stroke(); | |
} | |
} |
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/* Copyright 2011 the Dart project authors. All rights reserved. */ | |
/* Use of this source code is governed by a BSD-style license */ | |
/* that can be found in the LICENSE file. */ | |
h2 { | |
margin-bottom: 0; | |
text-align: center; | |
} | |
div { | |
text-align: center; | |
} |
Awesome
very good
https://github.com/dart-lang/dart-pad/wiki/Sharing-Guide
DartPad gist share tutorial
- create
index.html
- edit, add files
main.dart
&styles.css
demo
OK
wow that's awesome
index.html
Dr. Fibonacci's Sunflower Spectacular
0
1000
File
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Cool!!