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enjalot/README.md

Last active September 3, 2015 01:14
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visfest experiment #2
Raw
index.html
<!DOCTYPE html>
<head>
<meta charset="utf-8">
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
<script src="sampler.js"></script>
</head>
<body>
<svg width=960 height=500>
<g transform="translate(-50,0)">
<path id="outer" fill="none" stroke="#000000" stroke-width="0.8" stroke-miterlimit="10" d="M174.7,85c-24.5,14-57,18-45.8,45.7
c9.5,23.4-28.2,15.1-45.8-25.7s20.5-65.8,45.8-65.8S196.7,72.5,174.7,85Z"/>
<path id="inner" fill="none" stroke="#000000" stroke-width="0.8" stroke-miterlimit="10" d="M128.4,64.4c-1.9-0.1-5.9,6-5.9,6s-2.3-3.6-1-7.4
c1.4-3.8,3.4-3.5,5-3.1C128.3,60.2,141.8,65.1,128.4,64.4z"/>
</g>
<g id="output" transform="scale(3)translate(30,0)">
</g>
</svg>
<script>
var svg = d3.select("svg");
var inner = d3.select("#inner")
var outer = d3.select("#outer")
var numSamples = 20;
var numLines = 12;
var line = d3.svg.line()
.x(function(d) { return d.x })
.y(function(d) { return d.y })
//.interpolate("linear-closed")
.interpolate("cardinal-closed")
.interpolate("basis-closed")
var ins = Sampler.getSamples(inner.node(), numSamples);
var outs = Sampler.getSamples(outer.node(), numSamples);
var output = d3.select("#output")
var lines = [ins];
d3.range(numLines).forEach(function(index) {
var samples = []
var ratio = index / numLines;
var i, x, y;
for(i = 0; i < numSamples; i++) {
x = ins[i].x * ratio + outs[i].x * (1 - ratio);
y = ins[i].y * ratio + outs[i].y * (1 - ratio);
samples.push({ x: x, y: y})
}
lines.push(samples)
})
output.selectAll("path.blend")
.data(lines)
.enter()
.append("path").classed("blend", true)
.attr({
d: function(d) { return line(d) },
fill: "none",
stroke: "#ff005d"
})
</script>
</body>
Raw
sampler.js
var Sampler = function() {}
Sampler.getSamples = function(path, num) {
var len = path.getTotalLength()
var p, t;
var result = []
for(var i = 0; i < num; i++) {
p = path.getPointAtLength(i * len/num);
t = Sampler.getTangent(path, i/num * 100);
result.push({
x: p.x,
y: p.y,
point: p,
tangent: t,
perp: Sampler.rotate2d(t.v, 90)
});
}
return result
}
Sampler.getTangent = function(path, percent) {
// returns a normalized vector that describes the tangent
// at the point that is found at *percent* of the path's length
var fraction = percent/100;
if(fraction < 0) fraction = 0;
if(fraction > 0.99) fraction = 1;
var len = path.getTotalLength();
var point1 = path.getPointAtLength(fraction * len - 0.1);
var point2 = path.getPointAtLength(fraction * len + 0.1);
var vector = { x: point2.x - point1.x, y: point2.y - point1.y }
var magnitude = Math.sqrt(vector.x*vector.x + vector.y*vector.y);
vector.x /= magnitude;
vector.y /= magnitude;
return {p: point1, v: vector };
}
Sampler.rotate2d = function(vector, angle) {
//rotate a vector
angle *= Math.PI/180; //convert to radians
return {
x: vector.x * Math.cos(angle) - vector.y * Math.sin(angle),
y: vector.x * Math.sin(angle) + vector.y * Math.cos(angle)
}
}
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