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516 lines
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<!DOCTYPE html><html lang="en"><head>
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<title>Optimize Lots of Objects</title>
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</head>
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<div class="container">
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<div class="lesson-title">
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<h1>Optimize Lots of Objects</h1>
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</div>
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<div class="lesson">
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<div class="lesson-main">
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<p>This article is part of a series of articles about three.js. The first article
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is <a href="fundamentals.html">three.js fundamentals</a>. If you haven't read that
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yet and you're new to three.js you might want to consider starting there. </p>
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<p>There are many ways to optimize things for three.js. One way is often referred
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to as <em>merging geometry</em>. Every <a href="/docs/#api/en/objects/Mesh"><code class="notranslate" translate="no">Mesh</code></a> you create and three.js represents 1 or
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more requests by the system to draw something. Drawing 2 things has more
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overhead than drawing 1 even if the results are the same so one way to optimize
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is to merge meshes.</p>
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<p>Let's show an example of when this is a good solution for an issue. Let's
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re-create the <a href="https://globe.chromeexperiments.com/">WebGL Globe</a>.</p>
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<p>The first thing we need to do is get some data. The WebGL Globe said the data
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they use comes from <a href="http://sedac.ciesin.columbia.edu/gpw/">SEDAC</a>. Checking out
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the site I saw there was <a href="https://beta.sedac.ciesin.columbia.edu/data/set/gpw-v4-basic-demographic-characteristics-rev10">demographic data in a grid
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format</a>.
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I downloaded the data at 60 minute resolution. Then I took a look at the data</p>
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<p>It looks like this</p>
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<pre class="prettyprint showlinemods notranslate lang-txt" translate="no"> ncols 360
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nrows 145
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xllcorner -180
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yllcorner -60
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cellsize 0.99999999999994
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NODATA_value -9999
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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9.241768 8.790958 2.095345 -9999 0.05114867 -9999 -9999 -9999 -9999 -999...
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1.287993 0.4395509 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999...
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-9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
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</pre>
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<p>There's a few lines that are like key/value pairs followed by lines with a value
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per grid point, one line for each row of data points.</p>
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<p>To make sure we understand the data let's try to plot it in 2D.</p>
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<p>First some code to load the text file</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">async function loadFile(url) {
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const res = await fetch(url);
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return res.text();
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}
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</pre>
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<p>The code above returns a <code class="notranslate" translate="no">Promise</code> with the contents of the file at <code class="notranslate" translate="no">url</code>;</p>
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<p>Then we need some code to parse the file</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function parseData(text) {
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const data = [];
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const settings = {data};
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let max;
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let min;
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// split into lines
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text.split('\n').forEach((line) => {
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// split the line by whitespace
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const parts = line.trim().split(/\s+/);
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if (parts.length === 2) {
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// only 2 parts, must be a key/value pair
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settings[parts[0]] = parseFloat(parts[1]);
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} else if (parts.length > 2) {
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// more than 2 parts, must be data
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const values = parts.map((v) => {
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const value = parseFloat(v);
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if (value === settings.NODATA_value) {
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return undefined;
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}
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max = Math.max(max === undefined ? value : max, value);
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min = Math.min(min === undefined ? value : min, value);
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return value;
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});
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data.push(values);
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}
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});
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return Object.assign(settings, {min, max});
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}
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</pre>
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<p>The code above returns an object with all the key/value pairs from the file as
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well as a <code class="notranslate" translate="no">data</code> property with all the data in one large array and the <code class="notranslate" translate="no">min</code> and
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<code class="notranslate" translate="no">max</code> values found in the data.</p>
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<p>Then we need some code to draw that data</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function drawData(file) {
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const {min, max, data} = file;
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const range = max - min;
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const ctx = document.querySelector('canvas').getContext('2d');
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// make the canvas the same size as the data
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ctx.canvas.width = ncols;
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ctx.canvas.height = nrows;
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// but display it double size so it's not too small
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ctx.canvas.style.width = px(ncols * 2);
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ctx.canvas.style.height = px(nrows * 2);
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// fill the canvas to dark gray
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ctx.fillStyle = '#444';
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ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
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// draw each data point
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data.forEach((row, latNdx) => {
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row.forEach((value, lonNdx) => {
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if (value === undefined) {
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return;
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}
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const amount = (value - min) / range;
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const hue = 1;
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const saturation = 1;
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const lightness = amount;
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ctx.fillStyle = hsl(hue, saturation, lightness);
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ctx.fillRect(lonNdx, latNdx, 1, 1);
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});
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});
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}
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function px(v) {
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return `${v | 0}px`;
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}
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function hsl(h, s, l) {
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return `hsl(${h * 360 | 0},${s * 100 | 0}%,${l * 100 | 0}%)`;
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}
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</pre>
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<p>And finally gluing it all together</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">loadFile('resources/data/gpw/gpw_v4_basic_demographic_characteristics_rev10_a000_014mt_2010_cntm_1_deg.asc')
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.then(parseData)
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.then(drawData);
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</pre>
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<p>Gives us this result</p>
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<p></p><div translate="no" class="threejs_example_container notranslate">
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<div><iframe class="threejs_example notranslate" translate="no" style=" " src="/manual/examples/resources/editor.html?url=/manual/examples/gpw-data-viewer.html"></iframe></div>
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<a class="threejs_center" href="/manual/examples/gpw-data-viewer.html" target="_blank">click here to open in a separate window</a>
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</div>
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<p></p>
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<p>So that seems to work. </p>
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<p>Let's try it in 3D. Starting with the code from <a href="rendering-on-demand.html">rendering on
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demand</a> We'll make one box per data in the
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file.</p>
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<p>First let's make a simple sphere with a texture of the world. Here's the texture</p>
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<div class="threejs_center"><img src="../examples/resources/images/world.jpg" style="width: 600px"></div>
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<p>And the code to set it up.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">{
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const loader = new THREE.TextureLoader();
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const texture = loader.load('resources/images/world.jpg', render);
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const geometry = new THREE.SphereGeometry(1, 64, 32);
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const material = new THREE.MeshBasicMaterial({map: texture});
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scene.add(new THREE.Mesh(geometry, material));
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}
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</pre>
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<p>Notice the call to <code class="notranslate" translate="no">render</code> when the texture has finished loading. We need this
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because we're <a href="rendering-on-demand.html">rendering on demand</a> instead of
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continuously so we need to render once when the texture is loaded.</p>
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<p>Then we need to change the code that drew a dot per data point above to instead
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make a box per data point.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function addBoxes(file) {
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const {min, max, data} = file;
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const range = max - min;
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// make one box geometry
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const boxWidth = 1;
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const boxHeight = 1;
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const boxDepth = 1;
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const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);
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// make it so it scales away from the positive Z axis
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geometry.applyMatrix4(new THREE.Matrix4().makeTranslation(0, 0, 0.5));
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// these helpers will make it easy to position the boxes
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// We can rotate the lon helper on its Y axis to the longitude
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const lonHelper = new THREE.Object3D();
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scene.add(lonHelper);
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// We rotate the latHelper on its X axis to the latitude
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const latHelper = new THREE.Object3D();
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lonHelper.add(latHelper);
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// The position helper moves the object to the edge of the sphere
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const positionHelper = new THREE.Object3D();
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positionHelper.position.z = 1;
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latHelper.add(positionHelper);
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const lonFudge = Math.PI * .5;
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const latFudge = Math.PI * -0.135;
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data.forEach((row, latNdx) => {
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row.forEach((value, lonNdx) => {
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if (value === undefined) {
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return;
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}
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const amount = (value - min) / range;
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const material = new THREE.MeshBasicMaterial();
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const hue = THREE.MathUtils.lerp(0.7, 0.3, amount);
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const saturation = 1;
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const lightness = THREE.MathUtils.lerp(0.1, 1.0, amount);
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material.color.setHSL(hue, saturation, lightness);
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const mesh = new THREE.Mesh(geometry, material);
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scene.add(mesh);
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// adjust the helpers to point to the latitude and longitude
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lonHelper.rotation.y = THREE.MathUtils.degToRad(lonNdx + file.xllcorner) + lonFudge;
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latHelper.rotation.x = THREE.MathUtils.degToRad(latNdx + file.yllcorner) + latFudge;
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// use the world matrix of the position helper to
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// position this mesh.
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positionHelper.updateWorldMatrix(true, false);
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mesh.applyMatrix4(positionHelper.matrixWorld);
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mesh.scale.set(0.005, 0.005, THREE.MathUtils.lerp(0.01, 0.5, amount));
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});
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});
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}
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</pre>
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<p>The code is mostly straight forward from our test drawing code. </p>
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<p>We make one box and adjust its center so it scales away from positive Z. If we
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didn't do this it would scale from the center but we want them to grow away from the origin.</p>
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<div class="spread">
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<div>
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<div data-diagram="scaleCenter" style="height: 250px"></div>
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<div class="code">default</div>
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</div>
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<div>
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<div data-diagram="scalePositiveZ" style="height: 250px"></div>
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<div class="code">adjusted</div>
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</div>
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</div>
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<p>Of course we could also solve that by parenting the box to more <a href="/docs/#api/en/core/Object3D"><code class="notranslate" translate="no">THREE.Object3D</code></a>
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objects like we covered in <a href="scenegraph.html">scene graphs</a> but the more
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nodes we add to a scene graph the slower it gets.</p>
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<p>We also setup this small hierarchy of nodes of <code class="notranslate" translate="no">lonHelper</code>, <code class="notranslate" translate="no">latHelper</code>, and
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<code class="notranslate" translate="no">positionHelper</code>. We use these objects to compute a position around the sphere
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were to place the box. </p>
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<div class="spread">
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<div data-diagram="lonLatPos" style="width: 600px; height: 400px;"></div>
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</div>
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<p>Above the <span style="color: green;">green bar</span> represents <code class="notranslate" translate="no">lonHelper</code> and
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is used to rotate toward longitude on the equator. The <span style="color: blue;">
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blue bar</span> represents <code class="notranslate" translate="no">latHelper</code> which is used to rotate to a
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latitude above or below the equator. The <span style="color: red;">red
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sphere</span> represents the offset that that <code class="notranslate" translate="no">positionHelper</code> provides.</p>
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<p>We could do all of the math manually to figure out positions on the globe but
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doing it this way leaves most of the math to the library itself so we don't need
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to deal with.</p>
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<p>For each data point we create a <a href="/docs/#api/en/materials/MeshBasicMaterial"><code class="notranslate" translate="no">MeshBasicMaterial</code></a> and a <a href="/docs/#api/en/objects/Mesh"><code class="notranslate" translate="no">Mesh</code></a> and then we ask
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for the world matrix of the <code class="notranslate" translate="no">positionHelper</code> and apply that to the new <a href="/docs/#api/en/objects/Mesh"><code class="notranslate" translate="no">Mesh</code></a>.
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Finally we scale the mesh at its new position.</p>
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<p>Like above, we could also have created a <code class="notranslate" translate="no">latHelper</code>, <code class="notranslate" translate="no">lonHelper</code>, and
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<code class="notranslate" translate="no">positionHelper</code> for every new box but that would be even slower.</p>
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<p>There are up to 360x145 boxes we're going to create. That's up to 52000 boxes.
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Because some data points are marked as "NO_DATA" the actual number of boxes
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we're going to create is around 19000. If we added 3 extra helper objects per
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box that would be nearly 80000 scene graph nodes that THREE.js would have to
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compute positions for. By instead using one set of helpers to just position the
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meshes we save around 60000 operations.</p>
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<p>A note about <code class="notranslate" translate="no">lonFudge</code> and <code class="notranslate" translate="no">latFudge</code>. <code class="notranslate" translate="no">lonFudge</code> is π/2 which is a quarter of a turn.
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That makes sense. It just means the texture or texture coordinates start at a
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different offset around the globe. <code class="notranslate" translate="no">latFudge</code> on the other hand I have no idea
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why it needs to be π * -0.135, that's just an amount that made the boxes line up
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with the texture.</p>
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<p>The last thing we need to do is call our loader</p>
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<pre class="prettyprint showlinemods notranslate notranslate" translate="no">loadFile('resources/data/gpw/gpw_v4_basic_demographic_characteristics_rev10_a000_014mt_2010_cntm_1_deg.asc')
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.then(parseData)
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- .then(drawData)
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+ .then(addBoxes)
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+ .then(render);
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</pre><p>Once the data has finished loading and parsing then we need to render at least
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once since we're <a href="rendering-on-demand.html">rendering on demand</a>.</p>
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<p></p><div translate="no" class="threejs_example_container notranslate">
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<div><iframe class="threejs_example notranslate" translate="no" style=" " src="/manual/examples/resources/editor.html?url=/manual/examples/lots-of-objects-slow.html"></iframe></div>
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<a class="threejs_center" href="/manual/examples/lots-of-objects-slow.html" target="_blank">click here to open in a separate window</a>
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</div>
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<p></p>
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<p>If you try to rotate the example above by dragging on the sample you'll likely
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notice it's slow.</p>
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<p>We can check the framerate by <a href="debugging-javascript.html">opening the
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devtools</a> and turning on the browser's frame
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rate meter.</p>
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<div class="threejs_center"><img src="../resources/images/bring-up-fps-meter.gif"></div>
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<p>On my machine I see a framerate under 20fps.</p>
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<div class="threejs_center"><img src="../resources/images/fps-meter.gif"></div>
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<p>That doesn't feel very good to me and I suspect many people have slower machines
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which would make it even worse. We'd better look into optimizing.</p>
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<p>For this particular problem we can merge all the boxes into a single geometry.
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We're currently drawing around 19000 boxes. By merging them into a single
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geometry we'd remove 18999 operations.</p>
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<p>Here's the new code to merge the boxes into a single geometry.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function addBoxes(file) {
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const {min, max, data} = file;
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const range = max - min;
|
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- // make one box geometry
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- const boxWidth = 1;
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- const boxHeight = 1;
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- const boxDepth = 1;
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- const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);
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- // make it so it scales away from the positive Z axis
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- geometry.applyMatrix4(new THREE.Matrix4().makeTranslation(0, 0, 0.5));
|
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|
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// these helpers will make it easy to position the boxes
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// We can rotate the lon helper on its Y axis to the longitude
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const lonHelper = new THREE.Object3D();
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scene.add(lonHelper);
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// We rotate the latHelper on its X axis to the latitude
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const latHelper = new THREE.Object3D();
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lonHelper.add(latHelper);
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// The position helper moves the object to the edge of the sphere
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const positionHelper = new THREE.Object3D();
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positionHelper.position.z = 1;
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latHelper.add(positionHelper);
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+ // Used to move the center of the box so it scales from the position Z axis
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+ const originHelper = new THREE.Object3D();
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+ originHelper.position.z = 0.5;
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+ positionHelper.add(originHelper);
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const lonFudge = Math.PI * .5;
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const latFudge = Math.PI * -0.135;
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+ const geometries = [];
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data.forEach((row, latNdx) => {
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row.forEach((value, lonNdx) => {
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if (value === undefined) {
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return;
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}
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const amount = (value - min) / range;
|
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- const material = new THREE.MeshBasicMaterial();
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- const hue = THREE.MathUtils.lerp(0.7, 0.3, amount);
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- const saturation = 1;
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- const lightness = THREE.MathUtils.lerp(0.1, 1.0, amount);
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- material.color.setHSL(hue, saturation, lightness);
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- const mesh = new THREE.Mesh(geometry, material);
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- scene.add(mesh);
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+ const boxWidth = 1;
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+ const boxHeight = 1;
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+ const boxDepth = 1;
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+ const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);
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// adjust the helpers to point to the latitude and longitude
|
|
lonHelper.rotation.y = THREE.MathUtils.degToRad(lonNdx + file.xllcorner) + lonFudge;
|
|
latHelper.rotation.x = THREE.MathUtils.degToRad(latNdx + file.yllcorner) + latFudge;
|
|
|
|
- // use the world matrix of the position helper to
|
|
- // position this mesh.
|
|
- positionHelper.updateWorldMatrix(true, false);
|
|
- mesh.applyMatrix4(positionHelper.matrixWorld);
|
|
-
|
|
- mesh.scale.set(0.005, 0.005, THREE.MathUtils.lerp(0.01, 0.5, amount));
|
|
|
|
+ // use the world matrix of the origin helper to
|
|
+ // position this geometry
|
|
+ positionHelper.scale.set(0.005, 0.005, THREE.MathUtils.lerp(0.01, 0.5, amount));
|
|
+ originHelper.updateWorldMatrix(true, false);
|
|
+ geometry.applyMatrix4(originHelper.matrixWorld);
|
|
+
|
|
+ geometries.push(geometry);
|
|
});
|
|
});
|
|
|
|
+ const mergedGeometry = BufferGeometryUtils.mergeBufferGeometries(
|
|
+ geometries, false);
|
|
+ const material = new THREE.MeshBasicMaterial({color:'red'});
|
|
+ const mesh = new THREE.Mesh(mergedGeometry, material);
|
|
+ scene.add(mesh);
|
|
|
|
}
|
|
</pre>
|
|
<p>Above we removed the code that was changing the box geometry's center point and
|
|
are instead doing it by adding an <code class="notranslate" translate="no">originHelper</code>. Before we were using the same
|
|
geometry 19000 times. This time we are creating new geometry for every single
|
|
box and since we are going to use <code class="notranslate" translate="no">applyMatrix</code> to move the vertices of each box
|
|
geometry we might as well do it once instead of twice.</p>
|
|
<p>At the end we pass an array of all the geometries to
|
|
<code class="notranslate" translate="no">BufferGeometryUtils.mergeBufferGeometries</code> which will combined all of
|
|
them into a single mesh.</p>
|
|
<p>We also need to include the <code class="notranslate" translate="no">BufferGeometryUtils</code></p>
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">import * as BufferGeometryUtils from 'three/addons/utils/BufferGeometryUtils.js';
|
|
</pre>
|
|
<p>And now, at least on my machine, I get 60 frames per second</p>
|
|
<p></p><div translate="no" class="threejs_example_container notranslate">
|
|
<div><iframe class="threejs_example notranslate" translate="no" style=" " src="/manual/examples/resources/editor.html?url=/manual/examples/lots-of-objects-merged.html"></iframe></div>
|
|
<a class="threejs_center" href="/manual/examples/lots-of-objects-merged.html" target="_blank">click here to open in a separate window</a>
|
|
</div>
|
|
|
|
<p></p>
|
|
<p>So that worked but because it's one mesh we only get one material which means we
|
|
only get one color where as before we had a different color on each box. We can
|
|
fix that by using vertex colors.</p>
|
|
<p>Vertex colors add a color per vertex. By setting all the colors of each vertex
|
|
of each box to specific colors every box will have a different color.</p>
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">+const color = new THREE.Color();
|
|
|
|
const lonFudge = Math.PI * .5;
|
|
const latFudge = Math.PI * -0.135;
|
|
const geometries = [];
|
|
data.forEach((row, latNdx) => {
|
|
row.forEach((value, lonNdx) => {
|
|
if (value === undefined) {
|
|
return;
|
|
}
|
|
const amount = (value - min) / range;
|
|
|
|
const boxWidth = 1;
|
|
const boxHeight = 1;
|
|
const boxDepth = 1;
|
|
const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);
|
|
|
|
// adjust the helpers to point to the latitude and longitude
|
|
lonHelper.rotation.y = THREE.MathUtils.degToRad(lonNdx + file.xllcorner) + lonFudge;
|
|
latHelper.rotation.x = THREE.MathUtils.degToRad(latNdx + file.yllcorner) + latFudge;
|
|
|
|
// use the world matrix of the origin helper to
|
|
// position this geometry
|
|
positionHelper.scale.set(0.005, 0.005, THREE.MathUtils.lerp(0.01, 0.5, amount));
|
|
originHelper.updateWorldMatrix(true, false);
|
|
geometry.applyMatrix4(originHelper.matrixWorld);
|
|
|
|
+ // compute a color
|
|
+ const hue = THREE.MathUtils.lerp(0.7, 0.3, amount);
|
|
+ const saturation = 1;
|
|
+ const lightness = THREE.MathUtils.lerp(0.4, 1.0, amount);
|
|
+ color.setHSL(hue, saturation, lightness);
|
|
+ // get the colors as an array of values from 0 to 255
|
|
+ const rgb = color.toArray().map(v => v * 255);
|
|
+
|
|
+ // make an array to store colors for each vertex
|
|
+ const numVerts = geometry.getAttribute('position').count;
|
|
+ const itemSize = 3; // r, g, b
|
|
+ const colors = new Uint8Array(itemSize * numVerts);
|
|
+
|
|
+ // copy the color into the colors array for each vertex
|
|
+ colors.forEach((v, ndx) => {
|
|
+ colors[ndx] = rgb[ndx % 3];
|
|
+ });
|
|
+
|
|
+ const normalized = true;
|
|
+ const colorAttrib = new THREE.BufferAttribute(colors, itemSize, normalized);
|
|
+ geometry.setAttribute('color', colorAttrib);
|
|
|
|
geometries.push(geometry);
|
|
});
|
|
});
|
|
</pre>
|
|
<p>The code above looks up the number or vertices needed by getting the <code class="notranslate" translate="no">position</code>
|
|
attribute from the geometry. We then create a <code class="notranslate" translate="no">Uint8Array</code> to put the colors in.
|
|
It then adds that as an attribute by calling <code class="notranslate" translate="no">geometry.setAttribute</code>.</p>
|
|
<p>Lastly we need to tell three.js to use the vertex colors. </p>
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const mergedGeometry = BufferGeometryUtils.mergeBufferGeometries(
|
|
geometries, false);
|
|
-const material = new THREE.MeshBasicMaterial({color:'red'});
|
|
+const material = new THREE.MeshBasicMaterial({
|
|
+ vertexColors: true,
|
|
+});
|
|
const mesh = new THREE.Mesh(mergedGeometry, material);
|
|
scene.add(mesh);
|
|
</pre>
|
|
<p>And with that we get our colors back</p>
|
|
<p></p><div translate="no" class="threejs_example_container notranslate">
|
|
<div><iframe class="threejs_example notranslate" translate="no" style=" " src="/manual/examples/resources/editor.html?url=/manual/examples/lots-of-objects-merged-vertexcolors.html"></iframe></div>
|
|
<a class="threejs_center" href="/manual/examples/lots-of-objects-merged-vertexcolors.html" target="_blank">click here to open in a separate window</a>
|
|
</div>
|
|
|
|
<p></p>
|
|
<p>Merging geometry is a common optimization technique. For example rather than
|
|
100 trees you might merge the trees into 1 geometry, a pile of individual rocks
|
|
into a single geometry of rocks, a picket fence from individual pickets into
|
|
one fence mesh. Another example in Minecraft it doesn't likely draw each cube
|
|
individually but rather creates groups of merged cubes and also selectively removing
|
|
faces that are never visible.</p>
|
|
<p>The problem with making everything one mesh though is it's no longer easy
|
|
to move any part that was previously separate. Depending on our use case
|
|
though there are creative solutions. We'll explore one in
|
|
<a href="optimize-lots-of-objects-animated.html">another article</a>.</p>
|
|
<p><canvas id="c"></canvas></p>
|
|
<script type="module" src="../resources/threejs-lots-of-objects.js"></script>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
<script src="/manual/resources/prettify.js"></script>
|
|
<script src="/manual/resources/lesson.js"></script>
|
|
|
|
|
|
|
|
|
|
</body></html>
|