An update of Jason Davies’ Quadratic Koch Island Simplification stress test.
Snowflake Simplification
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license: gpl-3.0 |
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#!/usr/bin/env node | |
var width = 960, | |
height = 500; | |
console.log(JSON.stringify({ | |
type: "GeometryCollection", | |
geometries: [ | |
lSystem("FRFRFRFR", "FLFRFRFFLFLFRF", -Math.PI / 2, Math.PI / 2)(-128 + width * .35, height / 4), | |
lSystem("FRFRFRFR", "FLFRFRFFLFLFRF", -Math.PI / 2, Math.PI / 2)(128 + width * .35, height / 4) | |
] | |
})); | |
function lSystem(initial, replacement, left, right) { | |
var segments = initial.match(/F/g).length; | |
return function(x, y) { | |
var flake = initial, | |
iterations = 3, | |
d = 64 / Math.pow(segments, iterations - 1), | |
line = []; | |
for (var i = 0; i < iterations; ++i) flake = flake.replace(/F/g, replacement); | |
for (var angle = 0, move, i = 0, n = flake.length; i < n; ++i) { | |
move = flake.charAt(i); | |
if (move === "F") { | |
line.push([ | |
x += d * Math.cos(angle) | 0, | |
y += d * Math.sin(angle) | 0 | |
]); | |
} else { | |
angle += move === "L" ? left : right; | |
} | |
} | |
line.push(line[0]); | |
return {type: "Polygon", coordinates: [line]}; | |
}; | |
} |
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<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<style> | |
.koch { | |
fill: #eee; | |
stroke: #000; | |
} | |
.overlay { | |
fill: none; | |
pointer-events: all; | |
} | |
</style> | |
<body> | |
<script src="//d3js.org/d3.v3.min.js"></script> | |
<script src="//d3js.org/topojson.v1.min.js"></script> | |
<script> | |
var width = 960, | |
height = 500; | |
var area = 1, simplify = d3.geo.transform({ | |
point: function(x, y, z) { | |
if (z >= area) this.stream.point(x, y); | |
} | |
}); | |
var x = d3.scale.sqrt() | |
.domain([0, 1e4]) | |
.range([0, width]); | |
var path = d3.geo.path() | |
.projection(simplify); | |
var svg = d3.select("body").append("svg") | |
.attr("width", width) | |
.attr("height", height); | |
svg.append("rect") | |
.attr("class", "overlay") | |
.attr("width", width) | |
.attr("height", height) | |
.on("mousemove", mousemoved); | |
d3.json("snowflake.json", function(error, topo) { | |
if (error) throw error; | |
svg.insert("path", ".overlay") | |
.datum(topojson.feature(topojson.presimplify(topo), topo.objects.snowflake)) | |
.attr("class", "koch") | |
.attr("d", path); | |
}); | |
function mousemoved() { | |
area = x.invert(d3.mouse(this)[0]); | |
svg.select(".koch").attr("d", path); | |
} | |
</script> |
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all: snowflake.json | |
clean: | |
rm -f -- snowflake.json | |
snowflake.json: create-snowflake | |
./create-snowflake | \ | |
node_modules/.bin/topojson \ | |
-o $@ \ | |
-q 0 \ | |
--cartesian \ | |
-- \ | |
snowflake=/dev/stdin |
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{ | |
"name": "anonymous", | |
"version": "0.0.1", | |
"private": true, | |
"devDependencies": { | |
"topojson": "1" | |
} | |
} |
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