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Voronoi Circles
Raw
.block
license: gpl-3.0
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index.html
<!DOCTYPE html>
<meta charset="utf-8">
<canvas width="960" height="500"></canvas>
<script>
/* https://github.com/d3/d3-voronoi Copyright 2015 Mike Bostock */
!function(e,t){"object"==typeof exports&&"undefined"!=typeof module?t(exports):"function"==typeof define&&define.amd?define(["exports"],t):t(e.voronoi={})}(this,function(e){"use strict";function t(e){return function(){return e}}function n(e,t,n){return(e.x-n.x)*(t.y-e.y)-(e.x-t.x)*(n.y-e.y)}function i(e,t){return t.angle-e.angle}function r(e,t){this.l=e,this.r=t,this.a=this.b=null}function s(e,t,n){var i=new r(e,null);return i.a=t,i.b=n,D.push(i),i}function u(e,t,n){this.edge=e,this.site=t,this.angle=n}function f(e,t,n){var i=e.a,r=e.b;return new u(e,t,n?Math.atan2(n.y-t.y,n.x-t.x):e.l===t?Math.atan2(r.x-i.x,i.y-r.y):Math.atan2(i.x-r.x,r.y-i.y))}function a(e,t,n,i){for(var r,u,a,l,o,c,h,y,x,v,g=B.length;g--;)if(o=B[g],o&&o.prepare())for(h=o.edges,y=h.length,c=0;y>c;)v=h[c].end(),a=v.x,l=v.y,x=h[++c%y].start(),r=x.x,u=x.y,(Math.abs(a-r)>I||Math.abs(l-u)>I)&&(h.splice(c,0,f(s(o.site,v,Math.abs(a-e)<I&&i-l>I?{x:e,y:Math.abs(r-e)<I?u:i}:Math.abs(l-i)<I&&n-a>I?{x:Math.abs(u-i)<I?r:n,y:i}:Math.abs(a-n)<I&&l-t>I?{x:n,y:Math.abs(r-n)<I?u:t}:Math.abs(l-t)<I&&a-e>I?{x:Math.abs(u-t)<I?r:e,y:t}:null),o.site,null)),++y)}function l(e,t,n,i,r){var s,u=e.a,f=e.b,a=u.x,l=u.y,o=f.x,c=f.y,h=0,y=1,x=o-a,v=c-l;if(s=t-a,x||!(s>0)){if(s/=x,0>x){if(h>s)return;y>s&&(y=s)}else if(x>0){if(s>y)return;s>h&&(h=s)}if(s=i-a,x||!(0>s)){if(s/=x,0>x){if(s>y)return;s>h&&(h=s)}else if(x>0){if(h>s)return;y>s&&(y=s)}if(s=n-l,v||!(s>0)){if(s/=v,0>v){if(h>s)return;y>s&&(y=s)}else if(v>0){if(s>y)return;s>h&&(h=s)}if(s=r-l,v||!(0>s)){if(s/=v,0>v){if(s>y)return;s>h&&(h=s)}else if(v>0){if(h>s)return;y>s&&(y=s)}return h>0&&(e.a={x:a+h*x,y:l+h*v}),1>y&&(e.b={x:a+y*x,y:l+y*v}),e}}}}}function 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this._?(e=k(this._),t.P=null,t.N=e,e.P=e.L=t,n=e):(t.P=t.N=null,this._=t,n=null);for(t.L=t.R=null,t.U=n,t.C=!0,e=t;n&&n.C;)i=n.U,n===i.L?(r=i.R,r&&r.C?(n.C=r.C=!1,i.C=!0,e=i):(e===n.R&&(w(this,n),e=n,n=e.U),n.C=!1,i.C=!0,m(this,i))):(r=i.L,r&&r.C?(n.C=r.C=!1,i.C=!0,e=i):(e===n.L&&(m(this,n),e=n,n=e.U),n.C=!1,i.C=!0,w(this,i))),n=e.U;this._.C=!1},remove:function(e){e.N&&(e.N.P=e.P),e.P&&(e.P.N=e.N),e.N=e.P=null;var t,n,i,r=e.U,s=e.L,u=e.R;if(n=s?u?k(u):s:u,r?r.L===e?r.L=n:r.R=n:this._=n,s&&u?(i=n.C,n.C=e.C,n.L=s,s.U=n,n!==u?(r=n.U,n.U=e.U,e=n.R,r.L=e,n.R=u,u.U=n):(n.U=r,r=n,e=n.R)):(i=e.C,e=n),e&&(e.U=r),!i){if(e&&e.C)return void(e.C=!1);do{if(e===this._)break;if(e===r.L){if(t=r.R,t.C&&(t.C=!1,r.C=!0,w(this,r),t=r.R),t.L&&t.L.C||t.R&&t.R.C){t.R&&t.R.C||(t.L.C=!1,t.C=!0,m(this,t),t=r.R),t.C=r.C,r.C=t.R.C=!1,w(this,r),e=this._;break}}else 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/* https://github.com/d3/d3-timer Copyright 2015 Mike Bostock */
"undefined"==typeof requestAnimationFrame&&(requestAnimationFrame="undefined"!=typeof window&&(window.msRequestAnimationFrame||window.mozRequestAnimationFrame||window.webkitRequestAnimationFrame||window.oRequestAnimationFrame)||function(e){return setTimeout(e,17)}),function(e,n){"object"==typeof exports&&"undefined"!=typeof module?n(exports):"function"==typeof define&&define.amd?define(["exports"],n):n(e.timer={})}(this,function(e){"use strict";function n(){r=m=0,c=1/0,t(u())}function t(e){if(!r){var t=e-Date.now();t>24?c>e&&(m&&clearTimeout(m),m=setTimeout(n,t),c=e):(m&&(m=clearTimeout(m),c=1/0),r=requestAnimationFrame(n))}}function i(e,n,i){i=null==i?Date.now():+i,null!=n&&(i+=+n);var o={callback:e,time:i,flush:!1,next:null};a?a.next=o:f=o,a=o,t(i)}function o(e,n,t){t=null==t?Date.now():+t,null!=n&&(t+=+n),l.callback=e,l.time=t}function u(e){e=null==e?Date.now():+e;var n=l;for(l=f;l;)e>=l.time&&(l.flush=l.callback(e-l.time,e)),l=l.next;l=n,e=1/0;for(var t,i=f;i;)i.flush?i=t?t.next=i.next:f=i.next:(i.time<e&&(e=i.time),i=(t=i).next);return a=t,e}var a,m,r,f,l,c=1/0;e.timer=i,e.timerReplace=o,e.timerFlush=u});
var canvas = document.querySelector("canvas"),
width = canvas.width,
height = canvas.height,
context = canvas.getContext("2d"),
voro = voronoi.voronoi().extent([[0.5, 0.5], [width - 0.5, height - 0.5]]);
var n = 100,
particles = new Array(n);
for (var i = 0; i < n; ++i) particles[i] = {0: Math.random() * width, 1: Math.random() * height, vx: 0, vy: 0};
timer.timer(function(elapsed) {
for (var i = 0; i < n; ++i) {
var p = particles[i];
p[0] += p.vx; if (p[0] < 0) p[0] = p.vx *= -1; else if (p[0] > width) p[0] = width + (p.vx *= -1);
p[1] += p.vy; if (p[1] < 0) p[1] = p.vy *= -1; else if (p[1] > height) p[1] = height + (p.vy *= -1);
p.vx += 0.1 * (Math.random() - .5) - 0.01 * p.vx;
p.vy += 0.1 * (Math.random() - .5) - 0.01 * p.vy;
}
var cells = voro(particles);
context.clearRect(0, 0, width, height);
context.beginPath();
cells.forEach(function(cell) { drawPolygonIncircle(cell, -2.5); });
context.fillStyle = "#ddd";
context.fill();
context.beginPath();
cells.forEach(function(cell) { drawPolygon(cell); });
context.lineWidth = 1;
context.strokeStyle = "#aaa";
context.stroke();
context.beginPath();
particles.forEach(function(particle) { drawPoint(particle); });
context.fillStyle = "#000";
context.fill();
});
function drawPoint(point) {
context.moveTo(point[0] + 1.5, point[1]);
context.arc(point[0], point[1], 1.5, 0, 2 * Math.PI);
}
function drawPolygon(points) {
context.moveTo(points[0][0], points[0][1]);
for (var i = 1, n = points.length; i < n; ++i) context.lineTo(points[i][0], points[i][1]);
context.closePath();
}
function drawPolygonIncircle(points, offsetRadius) {
var circle = polygonIncircle(points),
radius = circle.radius + offsetRadius;
if (radius > 0) {
context.moveTo(circle[0] + radius, circle[1]);
context.arc(circle[0], circle[1], radius, 0, 2 * Math.PI);
}
}
// A horrible brute-force algorithm for determining the largest circle that can
// fit inside a convex polygon. For each distinct set of three sides of the
// polygon, compute the tangent circle. Then reduce the circle’s radius against
// the remaining sides of the polygon.
function polygonIncircle(points) {
var circle = {radius: 0};
for (var i = 0, n = points.length; i < n; ++i) {
var pi0 = points[i],
pi1 = points[(i + 1) % n];
for (var j = i + 1; j < n; ++j) {
var pj0 = points[j],
pj1 = points[(j + 1) % n],
pij = j === i + 1 ? pj0 : lineLineIntersection(pi0[0], pi0[1], pi1[0], pi1[1], pj0[0], pj0[1], pj1[0], pj1[1]);
search: for (var k = j + 1; k < n; ++k) {
var pk0 = points[k],
pk1 = points[(k + 1) % n],
pik = lineLineIntersection(pi0[0], pi0[1], pi1[0], pi1[1], pk0[0], pk0[1], pk1[0], pk1[1]),
pjk = k === j + 1 ? pk0 : lineLineIntersection(pj0[0], pj0[1], pj1[0], pj1[1], pk0[0], pk0[1], pk1[0], pk1[1]),
candidate = triangleIncircle(pij[0], pij[1], pik[0], pik[1], pjk[0], pjk[1]),
radius = candidate.radius;
for (var l = 0; l < n; ++l) {
var pl0 = points[l],
pl1 = points[(l + 1) % n],
r = pointLineDistance(candidate[0], candidate[1], pl0[0], pl0[1], pl1[0], pl1[1]);
if (r < circle.radius) continue search;
if (r < radius) radius = r;
}
circle = candidate;
circle.radius = radius;
}
}
}
return circle;
}
// Returns the incircle of the triangle 012.
function triangleIncircle(x0, y0, x1, y1, x2, y2) {
var x01 = x0 - x1, y01 = y0 - y1,
x02 = x0 - x2, y02 = y0 - y2,
x12 = x1 - x2, y12 = y1 - y2,
l01 = Math.sqrt(x01 * x01 + y01 * y01),
l02 = Math.sqrt(x02 * x02 + y02 * y02),
l12 = Math.sqrt(x12 * x12 + y12 * y12),
k0 = l01 / (l01 + l02),
k1 = l12 / (l12 + l01),
center = lineLineIntersection(x0, y0, x1 - k0 * x12, y1 - k0 * y12, x1, y1, x2 + k1 * x02, y2 + k1 * y02);
center.radius = Math.sqrt((l02 + l12 - l01) * (l12 + l01 - l02) * (l01 + l02 - l12) / (l01 + l02 + l12)) / 2;
return center;
}
// Returns the intersection of the infinite lines 01 and 23.
function lineLineIntersection(x0, y0, x1, y1, x2, y2, x3, y3) {
var x02 = x0 - x2, y02 = y0 - y2,
x10 = x1 - x0, y10 = y1 - y0,
x32 = x3 - x2, y32 = y3 - y2,
t = (x32 * y02 - y32 * x02) / (y32 * x10 - x32 * y10);
return [x0 + t * x10, y0 + t * y10];
}
// Returns the signed distance from point 0 to the infinite line 12.
function pointLineDistance(x0, y0, x1, y1, x2, y2) {
var x21 = x2 - x1, y21 = y2 - y1;
return (y21 * x0 - x21 * y0 + x2 * y1 - y2 * x1) / Math.sqrt(y21 * y21 + x21 * x21);
}
</script>
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