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472 lines
28 KiB
<!DOCTYPE html><html lang="en"><head>
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<meta charset="utf-8">
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<title>Shadows</title>
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</head>
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<body>
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<div class="container">
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<div class="lesson-title">
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<h1>Shadows</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
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first article is <a href="fundamentals.html">three.js fundamentals</a>. If
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you haven't read that yet and you're new to three.js you might want to
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consider starting there. The
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<a href="cameras.html">previous article was about cameras</a> which is
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important to have read before you read this article as well as
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the <a href="lights.html">article before that one about lights</a>.</p>
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<p>Shadows on computers can be a complicated topic. There are various
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solutions and all of them have tradeoffs including the solutions
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available in three.js.</p>
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<p>Three.js by default uses <em>shadow maps</em>. The way a shadow map works
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is, <em>for every light that casts shadows all objects marked to cast
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shadows are rendered from the point of view of the light</em>. <strong>READ THAT
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AGAIN!</strong> and let it sink in.</p>
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<p>In other words, if you have 20 objects, and 5 lights, and
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all 20 objects are casting shadows and all 5 lights are casting
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shadows then your entire scene will be drawn 6 times. All 20 objects
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will be drawn for light #1, then all 20 objects will be drawn for
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light #2, then #3, etc and finally the actual scene will be drawn
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using data from the first 5 renders.</p>
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<p>It gets worse, if you have a point light casting shadows the scene
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has to be drawn 6 times just for that light!</p>
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<p>For these reasons it's common to find other solutions than to have
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a bunch of lights all generating shadows. One common solution
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is to have multiple lights but only one directional light generating
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shadows.</p>
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<p>Yet another solution is to use lightmaps and or ambient occlusion maps
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to pre-compute the effects of lighting offline. This results in static
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lighting or static lighting hints but at least it's fast. We'll
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cover both of those in another article.</p>
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<p>Another solution is to use fake shadows. Make a plane, put a grayscale
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texture in the plane that approximates a shadow,
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draw it above the ground below your object.</p>
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<p>For example let's use this texture as a fake shadow</p>
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<div class="threejs_center"><img src="../examples/resources/images/roundshadow.png"></div>
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<p>We'll use some of the code from <a href="cameras.html">the previous article</a>.</p>
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<p>Let's set the background color to white.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const scene = new THREE.Scene();
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+scene.background = new THREE.Color('white');
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</pre>
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<p>Then we'll setup the same checkerboard ground but this time it's using
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a <a href="/docs/#api/en/materials/MeshBasicMaterial"><code class="notranslate" translate="no">MeshBasicMaterial</code></a> as we don't need lighting for the ground.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">+const loader = new THREE.TextureLoader();
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{
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const planeSize = 40;
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- const loader = new THREE.TextureLoader();
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const texture = loader.load('resources/images/checker.png');
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texture.wrapS = THREE.RepeatWrapping;
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texture.wrapT = THREE.RepeatWrapping;
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texture.magFilter = THREE.NearestFilter;
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const repeats = planeSize / 2;
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texture.repeat.set(repeats, repeats);
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const planeGeo = new THREE.PlaneGeometry(planeSize, planeSize);
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const planeMat = new THREE.MeshBasicMaterial({
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map: texture,
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side: THREE.DoubleSide,
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});
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+ planeMat.color.setRGB(1.5, 1.5, 1.5);
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const mesh = new THREE.Mesh(planeGeo, planeMat);
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mesh.rotation.x = Math.PI * -.5;
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scene.add(mesh);
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}
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</pre>
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<p>Note we're setting the color to <code class="notranslate" translate="no">1.5, 1.5, 1.5</code>. This will multiply the checkerboard
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texture's colors by 1.5, 1.5, 1.5. Since the texture's colors are 0x808080 and 0xC0C0C0
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which is medium gray and light gray, multiplying them by 1.5 will give us a white and
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light grey checkerboard.</p>
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<p>Let's load the shadow texture</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const shadowTexture = loader.load('resources/images/roundshadow.png');
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</pre>
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<p>and make an array to remember each sphere and associated objects.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const sphereShadowBases = [];
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</pre>
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<p>Then we'll make a sphere geometry</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const sphereRadius = 1;
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const sphereWidthDivisions = 32;
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const sphereHeightDivisions = 16;
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const sphereGeo = new THREE.SphereGeometry(sphereRadius, sphereWidthDivisions, sphereHeightDivisions);
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</pre>
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<p>And a plane geometry for the fake shadow</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const planeSize = 1;
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const shadowGeo = new THREE.PlaneGeometry(planeSize, planeSize);
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</pre>
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<p>Now we'll make a bunch of spheres. For each sphere we'll create a <code class="notranslate" translate="no">base</code>
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<a href="/docs/#api/en/core/Object3D"><code class="notranslate" translate="no">THREE.Object3D</code></a> and we'll make both the shadow plane mesh and the sphere mesh
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children of the base. That way if we move the base both the sphere and the shadow
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will move. We need to put the shadow slightly above the ground to prevent z-fighting.
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We also set <code class="notranslate" translate="no">depthWrite</code> to false so that the shadows don't mess each other up.
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We'll go over both of these issues in <a href="transparency.html">another article</a>.
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The shadow is a <a href="/docs/#api/en/materials/MeshBasicMaterial"><code class="notranslate" translate="no">MeshBasicMaterial</code></a> because it doesn't need lighting.</p>
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<p>We make each sphere a different hue and then save off the base, the sphere mesh,
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the shadow mesh and the initial y position of each sphere.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const numSpheres = 15;
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for (let i = 0; i < numSpheres; ++i) {
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// make a base for the shadow and the sphere
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// so they move together.
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const base = new THREE.Object3D();
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scene.add(base);
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// add the shadow to the base
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// note: we make a new material for each sphere
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// so we can set that sphere's material transparency
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// separately.
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const shadowMat = new THREE.MeshBasicMaterial({
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map: shadowTexture,
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transparent: true, // so we can see the ground
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depthWrite: false, // so we don't have to sort
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});
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const shadowMesh = new THREE.Mesh(shadowGeo, shadowMat);
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shadowMesh.position.y = 0.001; // so we're above the ground slightly
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shadowMesh.rotation.x = Math.PI * -.5;
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const shadowSize = sphereRadius * 4;
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shadowMesh.scale.set(shadowSize, shadowSize, shadowSize);
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base.add(shadowMesh);
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// add the sphere to the base
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const u = i / numSpheres; // goes from 0 to 1 as we iterate the spheres.
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const sphereMat = new THREE.MeshPhongMaterial();
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sphereMat.color.setHSL(u, 1, .75);
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const sphereMesh = new THREE.Mesh(sphereGeo, sphereMat);
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sphereMesh.position.set(0, sphereRadius + 2, 0);
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base.add(sphereMesh);
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// remember all 3 plus the y position
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sphereShadowBases.push({base, sphereMesh, shadowMesh, y: sphereMesh.position.y});
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}
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</pre>
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<p>We setup 2 lights. One is a <a href="/docs/#api/en/lights/HemisphereLight"><code class="notranslate" translate="no">HemisphereLight</code></a> with the intensity set to 2 to really
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brighten things up.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">{
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const skyColor = 0xB1E1FF; // light blue
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const groundColor = 0xB97A20; // brownish orange
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const intensity = 2;
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const light = new THREE.HemisphereLight(skyColor, groundColor, intensity);
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scene.add(light);
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}
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</pre>
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<p>The other is a <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> so the spheres get some definition</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">{
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const color = 0xFFFFFF;
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const intensity = 1;
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const light = new THREE.DirectionalLight(color, intensity);
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light.position.set(0, 10, 5);
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light.target.position.set(-5, 0, 0);
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scene.add(light);
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scene.add(light.target);
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}
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</pre>
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<p>It would render as is but let's animate there spheres.
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For each sphere, shadow, base set we move the base in the xz plane, we
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move the sphere up and down using <a href="/docs/#api/en/math/Math.abs(Math.sin(time))"><code class="notranslate" translate="no">Math.abs(Math.sin(time))</code></a>
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which gives us a bouncy animation. And, we also set the shadow material's
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opacity so that as each sphere goes higher its shadow fades out.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function render(time) {
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time *= 0.001; // convert to seconds
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...
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sphereShadowBases.forEach((sphereShadowBase, ndx) => {
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const {base, sphereMesh, shadowMesh, y} = sphereShadowBase;
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// u is a value that goes from 0 to 1 as we iterate the spheres
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const u = ndx / sphereShadowBases.length;
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// compute a position for the base. This will move
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// both the sphere and its shadow
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const speed = time * .2;
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const angle = speed + u * Math.PI * 2 * (ndx % 1 ? 1 : -1);
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const radius = Math.sin(speed - ndx) * 10;
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base.position.set(Math.cos(angle) * radius, 0, Math.sin(angle) * radius);
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// yOff is a value that goes from 0 to 1
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const yOff = Math.abs(Math.sin(time * 2 + ndx));
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// move the sphere up and down
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sphereMesh.position.y = y + THREE.MathUtils.lerp(-2, 2, yOff);
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// fade the shadow as the sphere goes up
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shadowMesh.material.opacity = THREE.MathUtils.lerp(1, .25, yOff);
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});
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...
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</pre>
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<p>And here's 15 kind of bouncing balls.</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/shadows-fake.html"></iframe></div>
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<a class="threejs_center" href="/manual/examples/shadows-fake.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>In some apps it's common to use a round or oval shadow for everything but
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of course you could also use different shaped shadow textures. You might also
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give the shadow a harder edge. A good example of using this type
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of shadow is <a href="https://www.google.com/search?tbm=isch&q=animal+crossing+pocket+camp+screenshots">Animal Crossing Pocket Camp</a>
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where you can see each character has a simple round shadow. It's effective and cheap.
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<a href="https://www.google.com/search?q=monument+valley+screenshots&tbm=isch">Monument Valley</a>
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appears to also use this kind of shadow for the main character.</p>
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<p>So, moving on to shadow maps, there are 3 lights which can cast shadows. The <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a>,
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the <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a>, and the <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a>.</p>
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<p>Let's start with the <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> with the helper example from <a href="lights.html">the lights article</a>.</p>
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<p>The first thing we need to do is turn on shadows in the renderer.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const renderer = new THREE.WebGLRenderer({canvas});
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+renderer.shadowMap.enabled = true;
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</pre>
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<p>Then we also need to tell the light to cast a shadow</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const light = new THREE.DirectionalLight(color, intensity);
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+light.castShadow = true;
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</pre>
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<p>We also need to go to each mesh in the scene and decide if it should
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both cast shadows and/or receive shadows.</p>
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<p>Let's make the plane (the ground) only receive shadows since we don't
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really care what happens underneath.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const mesh = new THREE.Mesh(planeGeo, planeMat);
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mesh.receiveShadow = true;
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</pre>
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<p>For the cube and the sphere let's have them both receive and cast shadows</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const mesh = new THREE.Mesh(cubeGeo, cubeMat);
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mesh.castShadow = true;
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mesh.receiveShadow = true;
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...
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const mesh = new THREE.Mesh(sphereGeo, sphereMat);
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mesh.castShadow = true;
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mesh.receiveShadow = true;
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</pre>
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<p>And then we run it.</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/shadows-directional-light.html"></iframe></div>
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<a class="threejs_center" href="/manual/examples/shadows-directional-light.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>What happened? Why are parts of the shadows missing?</p>
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<p>The reason is shadow maps are created by rendering the scene from the point
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of view of the light. In this case there is a camera at the <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a>
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that is looking at its target. Just like <a href="cameras.html">the camera's we previously covered</a>
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the light's shadow camera defines an area inside of which
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the shadows get rendered. In the example above that area is too small.</p>
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<p>In order to visualize that area we can get the light's shadow camera and add
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a <a href="/docs/#api/en/helpers/CameraHelper"><code class="notranslate" translate="no">CameraHelper</code></a> to the scene.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const cameraHelper = new THREE.CameraHelper(light.shadow.camera);
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scene.add(cameraHelper);
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</pre>
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<p>And now you can see the area for which shadows are cast and received.</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/shadows-directional-light-with-camera-helper.html"></iframe></div>
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<a class="threejs_center" href="/manual/examples/shadows-directional-light-with-camera-helper.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>Adjust the target x value back and forth and it should be pretty clear that only
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what's inside the light's shadow camera box is where shadows are drawn.</p>
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<p>We can adjust the size of that box by adjusting the light's shadow camera.</p>
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<p>Let's add some GUI setting to adjust the light's shadow camera box. Since a
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<a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> represents light all going in a parallel direction, the
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<a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> uses an <a href="/docs/#api/en/cameras/OrthographicCamera"><code class="notranslate" translate="no">OrthographicCamera</code></a> for its shadow camera.
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We went over how an <a href="/docs/#api/en/cameras/OrthographicCamera"><code class="notranslate" translate="no">OrthographicCamera</code></a> works in <a href="cameras.html">the previous article about cameras</a>.</p>
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<p>Recall an <a href="/docs/#api/en/cameras/OrthographicCamera"><code class="notranslate" translate="no">OrthographicCamera</code></a> defines
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its box or <em>view frustum</em> by its <code class="notranslate" translate="no">left</code>, <code class="notranslate" translate="no">right</code>, <code class="notranslate" translate="no">top</code>, <code class="notranslate" translate="no">bottom</code>, <code class="notranslate" translate="no">near</code>, <code class="notranslate" translate="no">far</code>,
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and <code class="notranslate" translate="no">zoom</code> properties.</p>
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<p>Again let's make a helper class for the lil-gui. We'll make a <code class="notranslate" translate="no">DimensionGUIHelper</code>
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that we'll pass an object and 2 properties. It will present one property that lil-gui
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can adjust and in response will set the two properties one positive and one negative.
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We can use this to set <code class="notranslate" translate="no">left</code> and <code class="notranslate" translate="no">right</code> as <code class="notranslate" translate="no">width</code> and <code class="notranslate" translate="no">up</code> and <code class="notranslate" translate="no">down</code> as <code class="notranslate" translate="no">height</code>.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class DimensionGUIHelper {
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constructor(obj, minProp, maxProp) {
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this.obj = obj;
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this.minProp = minProp;
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this.maxProp = maxProp;
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}
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get value() {
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return this.obj[this.maxProp] * 2;
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}
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set value(v) {
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this.obj[this.maxProp] = v / 2;
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this.obj[this.minProp] = v / -2;
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}
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}
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</pre>
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<p>We'll also use the <code class="notranslate" translate="no">MinMaxGUIHelper</code> we created in the <a href="cameras.html">camera article</a>
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to adjust <code class="notranslate" translate="no">near</code> and <code class="notranslate" translate="no">far</code>.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const gui = new GUI();
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gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
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gui.add(light, 'intensity', 0, 2, 0.01);
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+{
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+ const folder = gui.addFolder('Shadow Camera');
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+ folder.open();
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+ folder.add(new DimensionGUIHelper(light.shadow.camera, 'left', 'right'), 'value', 1, 100)
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+ .name('width')
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+ .onChange(updateCamera);
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+ folder.add(new DimensionGUIHelper(light.shadow.camera, 'bottom', 'top'), 'value', 1, 100)
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+ .name('height')
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+ .onChange(updateCamera);
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+ const minMaxGUIHelper = new MinMaxGUIHelper(light.shadow.camera, 'near', 'far', 0.1);
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+ folder.add(minMaxGUIHelper, 'min', 0.1, 50, 0.1).name('near').onChange(updateCamera);
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+ folder.add(minMaxGUIHelper, 'max', 0.1, 50, 0.1).name('far').onChange(updateCamera);
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+ folder.add(light.shadow.camera, 'zoom', 0.01, 1.5, 0.01).onChange(updateCamera);
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+}
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</pre>
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<p>We tell the GUI to call our <code class="notranslate" translate="no">updateCamera</code> function anytime anything changes.
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Let's write that function to update the light, the helper for the light, the
|
|
light's shadow camera, and the helper showing the light's shadow camera.</p>
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|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function updateCamera() {
|
|
// update the light target's matrixWorld because it's needed by the helper
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|
light.target.updateMatrixWorld();
|
|
helper.update();
|
|
// update the light's shadow camera's projection matrix
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|
light.shadow.camera.updateProjectionMatrix();
|
|
// and now update the camera helper we're using to show the light's shadow camera
|
|
cameraHelper.update();
|
|
}
|
|
updateCamera();
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|
</pre>
|
|
<p>And now that we've given the light's shadow camera a GUI we can play with the values.</p>
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|
<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/shadows-directional-light-with-camera-gui.html"></iframe></div>
|
|
<a class="threejs_center" href="/manual/examples/shadows-directional-light-with-camera-gui.html" target="_blank">click here to open in a separate window</a>
|
|
</div>
|
|
|
|
<p></p>
|
|
<p>Set the <code class="notranslate" translate="no">width</code> and <code class="notranslate" translate="no">height</code> to about 30 and you can see the shadows are correct
|
|
and the areas that need to be in shadow for this scene are entirely covered.</p>
|
|
<p>But this brings up the question, why not just set <code class="notranslate" translate="no">width</code> and <code class="notranslate" translate="no">height</code> to some
|
|
giant numbers to just cover everything? Set the <code class="notranslate" translate="no">width</code> and <code class="notranslate" translate="no">height</code> to 100
|
|
and you might see something like this</p>
|
|
<div class="threejs_center"><img src="../resources/images/low-res-shadow-map.png" style="width: 369px"></div>
|
|
|
|
<p>What's going on with these low-res shadows?!</p>
|
|
<p>This issue is yet another shadow related setting to be aware of.
|
|
Shadow maps are textures the shadows get drawn into.
|
|
Those textures have a size. The shadow camera's area we set above is stretched
|
|
across that size. That means the larger area you set, the more blocky your shadows will
|
|
be.</p>
|
|
<p>You can set the resolution of the shadow map's texture by setting <code class="notranslate" translate="no">light.shadow.mapSize.width</code>
|
|
and <code class="notranslate" translate="no">light.shadow.mapSize.height</code>. They default to 512x512.
|
|
The larger you make them the more memory they take and the slower they are to compute so you want
|
|
to set them as small as you can and still make your scene work. The same is true with the
|
|
light's shadow camera area. Smaller means better looking shadows so make the area as small as you
|
|
can and still cover your scene. Be aware that each user's machine has a maximum texture size
|
|
allowed which is available on the renderer as <a href="/docs/#api/en/renderers/WebGLRenderer#capabilities"><code class="notranslate" translate="no">renderer.capabilities.maxTextureSize</code></a>.</p>
|
|
<!--
|
|
Ok but what about `near` and `far` I hear you thinking. Can we set `near` to 0.00001 and far to `100000000`
|
|
-->
|
|
<p>Switching to the <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a> the light's shadow camera becomes a <a href="/docs/#api/en/cameras/PerspectiveCamera"><code class="notranslate" translate="no">PerspectiveCamera</code></a>. Unlike the <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a>'s shadow camera
|
|
where we could manually set most its settings, <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a>'s shadow camera is controlled by the <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a> itself. The <code class="notranslate" translate="no">fov</code> for the shadow
|
|
camera is directly connected to the <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a>'s <code class="notranslate" translate="no">angle</code> setting.
|
|
The <code class="notranslate" translate="no">aspect</code> is set automatically based on the size of the shadow map.</p>
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">-const light = new THREE.DirectionalLight(color, intensity);
|
|
+const light = new THREE.SpotLight(color, intensity);
|
|
</pre>
|
|
<p>and we added back in the <code class="notranslate" translate="no">penumbra</code> and <code class="notranslate" translate="no">angle</code> settings
|
|
from our <a href="lights.html">article about lights</a>.</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/shadows-spot-light-with-camera-gui.html"></iframe></div>
|
|
<a class="threejs_center" href="/manual/examples/shadows-spot-light-with-camera-gui.html" target="_blank">click here to open in a separate window</a>
|
|
</div>
|
|
|
|
<p></p>
|
|
<!--
|
|
You can notice, just like the last example if we set the angle high
|
|
then the shadow map, the texture is spread over a very large area and
|
|
the resolution of our shadows gets really low.
|
|
|
|
div class="threejs_center"><img src="../resources/images/low-res-shadow-map-spotlight.png" style="width: 344px"></div>
|
|
|
|
You can increase the size of the shadow map as mentioned above. You can
|
|
also blur the result
|
|
|
|
<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/shadows-spot-light-with-shadow-radius"></iframe></div>
|
|
<a class="threejs_center" href="/manual/examples/shadows-spot-light-with-shadow-radius" target="_blank">click here to open in a separate window</a>
|
|
</div>
|
|
|
|
|
|
-->
|
|
<p>And finally there's shadows with a <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a>. Since a <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a>
|
|
shines in all directions the only relevant settings are <code class="notranslate" translate="no">near</code> and <code class="notranslate" translate="no">far</code>.
|
|
Otherwise the <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a> shadow is effectively 6 <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a> shadows
|
|
each one pointing to the face of a cube around the light. This means
|
|
<a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a> shadows are much slower since the entire scene must be
|
|
drawn 6 times, one for each direction.</p>
|
|
<p>Let's put a box around our scene so we can see shadows on the walls
|
|
and ceiling. We'll set the material's <code class="notranslate" translate="no">side</code> property to <code class="notranslate" translate="no">THREE.BackSide</code>
|
|
so we render the inside of the box instead of the outside. Like the floor
|
|
we'll set it only to receive shadows. Also we'll set the position of the
|
|
box so its bottom is slightly below the floor so the floor and the bottom
|
|
of the box don't z-fight.</p>
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">{
|
|
const cubeSize = 30;
|
|
const cubeGeo = new THREE.BoxGeometry(cubeSize, cubeSize, cubeSize);
|
|
const cubeMat = new THREE.MeshPhongMaterial({
|
|
color: '#CCC',
|
|
side: THREE.BackSide,
|
|
});
|
|
const mesh = new THREE.Mesh(cubeGeo, cubeMat);
|
|
mesh.receiveShadow = true;
|
|
mesh.position.set(0, cubeSize / 2 - 0.1, 0);
|
|
scene.add(mesh);
|
|
}
|
|
</pre>
|
|
<p>And of course we need to switch the light to a <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a>.</p>
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">-const light = new THREE.SpotLight(color, intensity);
|
|
+const light = new THREE.PointLight(color, intensity);
|
|
|
|
....
|
|
|
|
// so we can easily see where the point light is
|
|
+const helper = new THREE.PointLightHelper(light);
|
|
+scene.add(helper);
|
|
</pre>
|
|
<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/shadows-point-light.html"></iframe></div>
|
|
<a class="threejs_center" href="/manual/examples/shadows-point-light.html" target="_blank">click here to open in a separate window</a>
|
|
</div>
|
|
|
|
<p></p>
|
|
<p>Use the <code class="notranslate" translate="no">position</code> GUI settings to move the light around
|
|
and you'll see the shadows fall on all the walls. You can
|
|
also adjust <code class="notranslate" translate="no">near</code> and <code class="notranslate" translate="no">far</code> settings and see just like
|
|
the other shadows when things are closer than <code class="notranslate" translate="no">near</code> they
|
|
no longer receive a shadow and they are further than <code class="notranslate" translate="no">far</code>
|
|
they are always in shadow.</p>
|
|
<!--
|
|
self shadow, shadow acne
|
|
-->
|
|
|
|
</div>
|
|
</div>
|
|
</div>
|
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<script src="/manual/resources/prettify.js"></script>
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<script src="/manual/resources/lesson.js"></script>
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</body></html>
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