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<h1 id="demo-delaunator-001">Demo Delaunator 001</h1>
<p>Delauney triangulation and Voronoi cell visualisation</p>
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<p><a href="../../demo/delaunator-001.html">Run code</a></p>
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<div class="content"><div class='highlight'><pre><span class="hljs-keyword">import</span> {
addNativeListener,
library <span class="hljs-keyword">as</span> L,
makeBlock,
makeEmitter,
makeRender,
makeStar,
makeWheel,
makeWorld,
} <span class="hljs-keyword">from</span> <span class="hljs-string">'../source/scrawl.js'</span>;</pre></div></div>
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<p>@ts-expect-error</p>
</div>
<div class="content"><div class='highlight'><pre><span class="hljs-keyword">import</span> <span class="hljs-title class_">Delaunator</span> <span class="hljs-keyword">from</span> <span class="hljs-string">'https://cdn.skypack.dev/delaunator@5.0.0'</span>;
<span class="hljs-keyword">import</span> { reportSpeed } <span class="hljs-keyword">from</span> <span class="hljs-string">'./utilities.js'</span>;</pre></div></div>
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<p>The following functions are used to handle the Delaunay object</p>
<ul>
<li>Code adapted from the <a href="https://mapbox.github.io/delaunator/">Delaunator Guide website</a></li>
</ul>
</div>
<div class="content"><div class='highlight'><pre><span class="hljs-keyword">const</span> <span class="hljs-title function_">edgesOfTriangle</span> = (<span class="hljs-params">t</span>) => [<span class="hljs-number">3</span> * t, <span class="hljs-number">3</span> * t + <span class="hljs-number">1</span>, <span class="hljs-number">3</span> * t + <span class="hljs-number">2</span>];
<span class="hljs-keyword">const</span> <span class="hljs-title function_">pointsOfTriangle</span> = (<span class="hljs-params">del, t</span>) => {
<span class="hljs-keyword">let</span> { triangles } = del;
<span class="hljs-keyword">return</span> <span class="hljs-title function_">edgesOfTriangle</span>(t).<span class="hljs-title function_">map</span>(<span class="hljs-function"><span class="hljs-params">e</span> =></span> triangles[e]);
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">triangleOfEdge</span> = (<span class="hljs-params">e</span>) => <span class="hljs-title class_">Math</span>.<span class="hljs-title function_">floor</span>(e / <span class="hljs-number">3</span>);
<span class="hljs-keyword">const</span> <span class="hljs-title function_">nextHalfedge</span> = (<span class="hljs-params">e</span>) => (e % <span class="hljs-number">3</span> === <span class="hljs-number">2</span>) ? e - <span class="hljs-number">2</span> : e + <span class="hljs-number">1</span>;
<span class="hljs-keyword">const</span> <span class="hljs-title function_">prevHalfedge</span> = (<span class="hljs-params">e</span>) => (e % <span class="hljs-number">3</span> === <span class="hljs-number">0</span>) ? e + <span class="hljs-number">2</span> : e - <span class="hljs-number">1</span>;
<span class="hljs-keyword">const</span> <span class="hljs-title function_">forEachTriangleEdge</span> = (<span class="hljs-params">pts, del, cb</span>) => {
<span class="hljs-keyword">let</span> { triangles, halfedges } = del;
<span class="hljs-keyword">let</span> len = triangles.<span class="hljs-property">length</span>;
<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> e = <span class="hljs-number">0</span>; e < len; e++) {
<span class="hljs-keyword">if</span> (e > halfedges[e]) {
<span class="hljs-keyword">const</span> p = pts[triangles[e]];
<span class="hljs-keyword">const</span> q = pts[triangles[<span class="hljs-title function_">nextHalfedge</span>(e)]];
<span class="hljs-title function_">cb</span>(e, p, q);
}
}
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">forEachTriangle</span> = (<span class="hljs-params">pts, del, cb</span>) => {
<span class="hljs-keyword">let</span> len = del.<span class="hljs-property">triangles</span>.<span class="hljs-property">length</span> / <span class="hljs-number">3</span>;
<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> t = <span class="hljs-number">0</span>; t < len; t++) {
<span class="hljs-title function_">cb</span>(t, <span class="hljs-title function_">pointsOfTriangle</span>(del, t).<span class="hljs-title function_">map</span>(<span class="hljs-function"><span class="hljs-params">p</span> =></span> pts[p]));
}
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">triangleCenter</span> = (<span class="hljs-params">pts, del, t</span>) => {
<span class="hljs-keyword">const</span> vertices = <span class="hljs-title function_">pointsOfTriangle</span>(del, t).<span class="hljs-title function_">map</span>(<span class="hljs-function"><span class="hljs-params">p</span> =></span> pts[p]);
<span class="hljs-keyword">return</span> <span class="hljs-title function_">circumcenter</span>(vertices[<span class="hljs-number">0</span>], vertices[<span class="hljs-number">1</span>], vertices[<span class="hljs-number">2</span>]);
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">trianglesAdjacentToTriangle</span> = (<span class="hljs-params">del, t</span>) => {
<span class="hljs-keyword">let</span> { halfedges } = del;
<span class="hljs-keyword">const</span> adjacent = [];
<span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> e <span class="hljs-keyword">of</span> <span class="hljs-title function_">edgesOfTriangle</span>(t)) {
<span class="hljs-keyword">const</span> opposite = halfedges[e];
<span class="hljs-keyword">if</span> (opposite >= <span class="hljs-number">0</span>) adjacent.<span class="hljs-title function_">push</span>(<span class="hljs-title function_">triangleOfEdge</span>(opposite));
}
<span class="hljs-keyword">return</span> adjacent;
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">circumcenter</span> = (<span class="hljs-params">a, b, c</span>) => {
<span class="hljs-keyword">if</span> (a && b && c && a.<span class="hljs-property">length</span> && b.<span class="hljs-property">length</span> && c.<span class="hljs-property">length</span>) {
<span class="hljs-keyword">const</span> ad = a[<span class="hljs-number">0</span>] * a[<span class="hljs-number">0</span>] + a[<span class="hljs-number">1</span>] * a[<span class="hljs-number">1</span>],
bd = b[<span class="hljs-number">0</span>] * b[<span class="hljs-number">0</span>] + b[<span class="hljs-number">1</span>] * b[<span class="hljs-number">1</span>],
cd = c[<span class="hljs-number">0</span>] * c[<span class="hljs-number">0</span>] + c[<span class="hljs-number">1</span>] * c[<span class="hljs-number">1</span>];
<span class="hljs-keyword">const</span> D = <span class="hljs-number">2</span> * (a[<span class="hljs-number">0</span>] * (b[<span class="hljs-number">1</span>] - c[<span class="hljs-number">1</span>]) + b[<span class="hljs-number">0</span>] * (c[<span class="hljs-number">1</span>] - a[<span class="hljs-number">1</span>]) + c[<span class="hljs-number">0</span>] * (a[<span class="hljs-number">1</span>] - b[<span class="hljs-number">1</span>]));
<span class="hljs-keyword">return</span> [
<span class="hljs-number">1</span> / D * (ad * (b[<span class="hljs-number">1</span>] - c[<span class="hljs-number">1</span>]) + bd * (c[<span class="hljs-number">1</span>] - a[<span class="hljs-number">1</span>]) + cd * (a[<span class="hljs-number">1</span>] - b[<span class="hljs-number">1</span>])),
<span class="hljs-number">1</span> / D * (ad * (c[<span class="hljs-number">0</span>] - b[<span class="hljs-number">0</span>]) + bd * (a[<span class="hljs-number">0</span>] - c[<span class="hljs-number">0</span>]) + cd * (b[<span class="hljs-number">0</span>] - a[<span class="hljs-number">0</span>])),
];
}
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">forEachVoronoiEdge</span> = (<span class="hljs-params">pts, del, cb</span>) => {
<span class="hljs-keyword">if</span> (del) {
<span class="hljs-keyword">let</span> { triangles, halfedges } = del;
<span class="hljs-keyword">let</span> len = triangles.<span class="hljs-property">length</span>;
<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> e = <span class="hljs-number">0</span>; e < len; e++) {
<span class="hljs-keyword">if</span> (e < halfedges[e]) {
<span class="hljs-keyword">const</span> p = <span class="hljs-title function_">triangleCenter</span>(pts, del, <span class="hljs-title function_">triangleOfEdge</span>(e));
<span class="hljs-keyword">const</span> q = <span class="hljs-title function_">triangleCenter</span>(pts, del, <span class="hljs-title function_">triangleOfEdge</span>(halfedges[e]));
<span class="hljs-title function_">cb</span>(e, p, q);
}
}
}
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">edgesAroundPoint</span> = (<span class="hljs-params">del, start</span>) => {
<span class="hljs-keyword">let</span> { halfedges } = del;
<span class="hljs-keyword">const</span> result = [];
<span class="hljs-keyword">let</span> incoming = start;
<span class="hljs-keyword">do</span> {
result.<span class="hljs-title function_">push</span>(incoming);
<span class="hljs-keyword">const</span> outgoing = <span class="hljs-title function_">nextHalfedge</span>(incoming);
incoming = halfedges[outgoing];
} <span class="hljs-keyword">while</span> (incoming !== -<span class="hljs-number">1</span> && incoming !== start);
<span class="hljs-keyword">return</span> result;
};
<span class="hljs-keyword">const</span> <span class="hljs-title function_">forEachVoronoiCell</span> = (<span class="hljs-params">pts, del, cb</span>) => {
<span class="hljs-keyword">const</span> index = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Map</span>();
<span class="hljs-keyword">let</span> { triangles, halfedges } = del;
<span class="hljs-keyword">let</span> tLen = triangles.<span class="hljs-property">length</span>,
pLen = pts.<span class="hljs-property">length</span>;
<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> e = <span class="hljs-number">0</span>; e < tLen; e++) {
<span class="hljs-keyword">const</span> endpoint = triangles[<span class="hljs-title function_">nextHalfedge</span>(e)];
<span class="hljs-keyword">if</span> (!index.<span class="hljs-title function_">has</span>(endpoint) || halfedges[e] === -<span class="hljs-number">1</span>) index.<span class="hljs-title function_">set</span>(endpoint, e);
}
<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> p = <span class="hljs-number">0</span>; p < pLen; p++) {
<span class="hljs-keyword">const</span> incoming = index.<span class="hljs-title function_">get</span>(p);
<span class="hljs-keyword">const</span> E = <span class="hljs-title function_">edgesAroundPoint</span>(del, incoming);
<span class="hljs-keyword">const</span> T = E.<span class="hljs-title function_">map</span>(triangleOfEdge);
<span class="hljs-keyword">const</span> V = T.<span class="hljs-title function_">map</span>(<span class="hljs-function"><span class="hljs-params">t</span> =></span> <span class="hljs-title function_">triangleCenter</span>(pts, del, t));
<span class="hljs-title function_">cb</span>(p, V);
}
};</pre></div></div>
</li>
<li id="section-5">
<div class="annotation">
<div class="sswrap ">
<a class="ss" href="#section-5">§</a>
</div>
<h4 id="scene-setup">Scene setup</h4>
</div>
<div class="content"><div class='highlight'><pre><span class="hljs-keyword">let</span> canvas = L.<span class="hljs-property">artefact</span>.<span class="hljs-property">mycanvas</span>;</pre></div></div>
</li>
<li id="section-6">
<div class="annotation">
<div class="sswrap ">
<a class="ss" href="#section-6">§</a>
</div>
<p>Create a Block entity which covers the entire canvas; this will act as the area in which particles will be generated by the Emitter entity</p>
</div>
<div class="content"><div class='highlight'><pre><span class="hljs-title function_">makeBlock</span>({
<span class="hljs-attr">name</span>: <span class="hljs-string">'field-block'</span>,
<span class="hljs-attr">order</span>: <span class="hljs-number">1</span>,
<span class="hljs-attr">width</span>: <span class="hljs-string">'100%'</span>,
<span class="hljs-attr">height</span>: <span class="hljs-string">'100%'</span>,
<span class="hljs-attr">method</span>: <span class="hljs-string">'none'</span>,
});
<span class="hljs-title function_">makeWheel</span>({
<span class="hljs-attr">name</span>: <span class="hljs-string">'mouse-planet'</span>,
<span class="hljs-attr">radius</span>: <span class="hljs-number">12</span>,
<span class="hljs-attr">handle</span>: [<span class="hljs-string">'center'</span>, <span class="hljs-string">'center'</span>],
<span class="hljs-attr">fillStyle</span>: <span class="hljs-string">'gold'</span>,
<span class="hljs-attr">lockTo</span>: <span class="hljs-string">'mouse'</span>,
});</pre></div></div>
</li>
<li id="section-7">
<div class="annotation">
<div class="sswrap ">
<a class="ss" href="#section-7">§</a>
</div>
<h4 id="particle-physics-animation-scene">Particle physics animation scene</h4>
</div>
</li>
<li id="section-8">
<div class="annotation">
<div class="sswrap ">
<a class="ss" href="#section-8">§</a>
</div>
<p>Create a World object which we can then assign to the particle emitter</p>
</div>
<div class="content"><div class='highlight'><pre><span class="hljs-keyword">let</span> myWorld = <span class="hljs-title function_">makeWorld</span>({
<span class="hljs-attr">name</span>: <span class="hljs-string">'demo-world'</span>,
<span class="hljs-attr">tickMultiplier</span>: <span class="hljs-number">2</span>,
<span class="hljs-attr">userAttributes</span>: [
{
<span class="hljs-attr">key</span>: <span class="hljs-string">'coords'</span>,
<span class="hljs-attr">defaultValue</span>: [],</pre></div></div>
</li>
<li id="section-9">
<div class="annotation">
<div class="sswrap ">
<a class="ss" href="#section-9">§</a>
</div>
<p>@ts-expect-error</p>
</div>
<div class="content"><div class='highlight'><pre> <span class="hljs-attr">getter</span>: <span class="hljs-keyword">function</span> (<span class="hljs-params"></span>) { <span class="hljs-keyword">return</span> [].<span class="hljs-title function_">concat</span>(<span class="hljs-variable language_">this</span>.<span class="hljs-property">coords</span>) },
<span class="hljs-attr">setter</span>: <span class="hljs-keyword">function</span> (<span class="hljs-params">emitter</span>) {</pre></div></div>
</li>
<li id="section-10">
<div class="annotation">
<div class="sswrap ">
<a class="ss" href="#section-10">§</a>
</div>
<p>@ts-expect-error</p>
</div>
<div class="content"><div class='highlight'><pre> <span class="hljs-keyword">let</span> { coords } = <span class="hljs-variable language_">this</span>;
coords.<span class="hljs-property">length<