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- <title>Lights</title>
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- <h1>Lights</h1>
- </div>
- <div class="lesson">
- <div class="lesson-main">
- <p>This article is part of a series of articles about three.js. The
- first article is <a href="fundamentals.html">three.js fundamentals</a>. If
- you haven't read that yet and you're new to three.js you might want to
- consider starting there and also the article on <a href="setup.html">setting up your environment</a>. The
- <a href="textures.html">previous article was about textures</a>.</p>
- <p>Let's go over how to use the various kinds of lights in three.</p>
- <p>Starting with one of our previous samples let's update the camera.
- We'll set the field of view to 45 degrees, the far plane to 100 units,
- and we'll move the camera 10 units up and 20 units back from the origin</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">*const fov = 45;
- const aspect = 2; // the canvas default
- const near = 0.1;
- *const far = 100;
- const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
- +camera.position.set(0, 10, 20);
- </pre>
- <p>Next let's add <a href="/docs/#examples/controls/OrbitControls"><code class="notranslate" translate="no">OrbitControls</code></a>. <a href="/docs/#examples/controls/OrbitControls"><code class="notranslate" translate="no">OrbitControls</code></a> let the user spin
- or <em>orbit</em> the camera around some point. The <a href="/docs/#examples/controls/OrbitControls"><code class="notranslate" translate="no">OrbitControls</code></a> are
- an optional feature of three.js so first we need to include them
- in our page</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">import * as THREE from 'three';
- +import {OrbitControls} from 'three/addons/controls/OrbitControls.js';
- </pre>
- <p>Then we can use them. We pass the <a href="/docs/#examples/controls/OrbitControls"><code class="notranslate" translate="no">OrbitControls</code></a> a camera to
- control and the DOM element to use to get input events</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const controls = new OrbitControls(camera, canvas);
- controls.target.set(0, 5, 0);
- controls.update();
- </pre>
- <p>We also set the target to orbit around to 5 units above the origin
- and then call <code class="notranslate" translate="no">controls.update</code> so the controls will use the new
- target.</p>
- <p>Next up let's make some things to light up. First we'll make ground
- plane. We'll apply a tiny 2x2 pixel checkerboard texture that looks
- like this</p>
- <div class="threejs_center">
- <img src="../examples/resources/images/checker.png" class="border" style="
- image-rendering: pixelated;
- width: 128px;
- ">
- </div>
- <p>First we load the texture, set it to repeating, set the filtering to
- nearest, and set how many times we want it to repeat. Since the
- texture is a 2x2 pixel checkerboard, by repeating and setting the
- repeat to half the size of the plane each check on the checkerboard
- will be exactly 1 unit large;</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const planeSize = 40;
- const loader = new THREE.TextureLoader();
- const texture = loader.load('resources/images/checker.png');
- texture.wrapS = THREE.RepeatWrapping;
- texture.wrapT = THREE.RepeatWrapping;
- texture.magFilter = THREE.NearestFilter;
- texture.colorSpace = THREE.SRGBColorSpace;
- const repeats = planeSize / 2;
- texture.repeat.set(repeats, repeats);
- </pre>
- <p>We then make a plane geometry, a material for the plane, and a mesh
- to insert it in the scene. Planes default to being in the XY plane
- but the ground is in the XZ plane so we rotate it.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const planeGeo = new THREE.PlaneGeometry(planeSize, planeSize);
- const planeMat = new THREE.MeshPhongMaterial({
- map: texture,
- side: THREE.DoubleSide,
- });
- const mesh = new THREE.Mesh(planeGeo, planeMat);
- mesh.rotation.x = Math.PI * -.5;
- scene.add(mesh);
- </pre>
- <p>Let's add a cube and a sphere so we have 3 things to light including the plane</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">{
- const cubeSize = 4;
- const cubeGeo = new THREE.BoxGeometry(cubeSize, cubeSize, cubeSize);
- const cubeMat = new THREE.MeshPhongMaterial({color: '#8AC'});
- const mesh = new THREE.Mesh(cubeGeo, cubeMat);
- mesh.position.set(cubeSize + 1, cubeSize / 2, 0);
- scene.add(mesh);
- }
- {
- const sphereRadius = 3;
- const sphereWidthDivisions = 32;
- const sphereHeightDivisions = 16;
- const sphereGeo = new THREE.SphereGeometry(sphereRadius, sphereWidthDivisions, sphereHeightDivisions);
- const sphereMat = new THREE.MeshPhongMaterial({color: '#CA8'});
- const mesh = new THREE.Mesh(sphereGeo, sphereMat);
- mesh.position.set(-sphereRadius - 1, sphereRadius + 2, 0);
- scene.add(mesh);
- }
- </pre>
- <p>Now that we have a scene to light up let's add lights!</p>
- <h2 id="-ambientlight-"><a href="/docs/#api/en/lights/AmbientLight"><code class="notranslate" translate="no">AmbientLight</code></a></h2>
- <p>First let's make an <a href="/docs/#api/en/lights/AmbientLight"><code class="notranslate" translate="no">AmbientLight</code></a></p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const color = 0xFFFFFF;
- const intensity = 1;
- const light = new THREE.AmbientLight(color, intensity);
- scene.add(light);
- </pre>
- <p>Let's also make it so we can adjust the light's parameters.
- We'll use <a href="https://github.com/georgealways/lil-gui">lil-gui</a> again.
- To be able to adjust the color via lil-gui we need a small helper
- that presents a property to lil-gui that looks like a CSS hex color string
- (eg: <code class="notranslate" translate="no">#FF8844</code>). Our helper will get the color from a named property,
- convert it to a hex string to offer to lil-gui. When lil-gui tries
- to set the helper's property we'll assign the result back to the light's
- color.</p>
- <p>Here's the helper:</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ColorGUIHelper {
- constructor(object, prop) {
- this.object = object;
- this.prop = prop;
- }
- get value() {
- return `#${this.object[this.prop].getHexString()}`;
- }
- set value(hexString) {
- this.object[this.prop].set(hexString);
- }
- }
- </pre>
- <p>And here's our code setting up lil-gui</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const gui = new GUI();
- gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
- gui.add(light, 'intensity', 0, 2, 0.01);
- </pre>
- <p>And here's the result</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/lights-ambient.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-ambient.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>Click and drag in the scene to <em>orbit</em> the camera.</p>
- <p>Notice there is no definition. The shapes are flat. The <a href="/docs/#api/en/lights/AmbientLight"><code class="notranslate" translate="no">AmbientLight</code></a> effectively
- just multiplies the material's color by the light's color times the
- intensity.</p>
- <pre class="prettyprint showlinemods notranslate notranslate" translate="no">color = materialColor * light.color * light.intensity;
- </pre><p>That's it. It has no direction.
- This style of ambient lighting is actually not all that
- useful as lighting as it's 100% even so other than changing the color
- of everything in the scene it doesn't look much like <em>lighting</em>.
- What it does help with is making the darks not too dark.</p>
- <h2 id="-hemispherelight-"><a href="/docs/#api/en/lights/HemisphereLight"><code class="notranslate" translate="no">HemisphereLight</code></a></h2>
- <p>Let's switch the code to a <a href="/docs/#api/en/lights/HemisphereLight"><code class="notranslate" translate="no">HemisphereLight</code></a>. A <a href="/docs/#api/en/lights/HemisphereLight"><code class="notranslate" translate="no">HemisphereLight</code></a>
- takes a sky color and a ground color and just multiplies the
- material's color between those 2 colors—the sky color if the
- surface of the object is pointing up and the ground color if
- the surface of the object is pointing down.</p>
- <p>Here's the new code</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">-const color = 0xFFFFFF;
- +const skyColor = 0xB1E1FF; // light blue
- +const groundColor = 0xB97A20; // brownish orange
- const intensity = 1;
- -const light = new THREE.AmbientLight(color, intensity);
- +const light = new THREE.HemisphereLight(skyColor, groundColor, intensity);
- scene.add(light);
- </pre>
- <p>Let's also update the lil-gui code to edit both colors</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const gui = new GUI();
- -gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
- +gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('skyColor');
- +gui.addColor(new ColorGUIHelper(light, 'groundColor'), 'value').name('groundColor');
- gui.add(light, 'intensity', 0, 2, 0.01);
- </pre>
- <p>The result:</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/lights-hemisphere.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-hemisphere.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>Notice again there is almost no definition, everything looks kind
- of flat. The <a href="/docs/#api/en/lights/HemisphereLight"><code class="notranslate" translate="no">HemisphereLight</code></a> used in combination with another light
- can help give a nice kind of influence of the color of the sky
- and ground. In that way it's best used in combination with some
- other light or a substitute for an <a href="/docs/#api/en/lights/AmbientLight"><code class="notranslate" translate="no">AmbientLight</code></a>.</p>
- <h2 id="-directionallight-"><a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a></h2>
- <p>Let's switch the code to a <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a>.
- A <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> is often used to represent the sun.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const color = 0xFFFFFF;
- const intensity = 1;
- const light = new THREE.DirectionalLight(color, intensity);
- light.position.set(0, 10, 0);
- light.target.position.set(-5, 0, 0);
- scene.add(light);
- scene.add(light.target);
- </pre>
- <p>Notice that we had to add the <code class="notranslate" translate="no">light</code> and the <code class="notranslate" translate="no">light.target</code>
- to the scene. A three.js <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> will shine
- in the direction of its target.</p>
- <p>Let's make it so we can move the target by adding it to
- our GUI.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const gui = new GUI();
- gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
- gui.add(light, 'intensity', 0, 2, 0.01);
- gui.add(light.target.position, 'x', -10, 10);
- gui.add(light.target.position, 'z', -10, 10);
- gui.add(light.target.position, 'y', 0, 10);
- </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/lights-directional.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-directional.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>It's kind of hard to see what's going on. Three.js has a bunch
- of helper objects we can add to our scene to help visualize
- invisible parts of a scene. In this case we'll use the
- <a href="/docs/#api/en/helpers/DirectionalLightHelper"><code class="notranslate" translate="no">DirectionalLightHelper</code></a> which will draw a plane, to represent
- the light, and a line from the light to the target. We just
- pass it the light and add it to the scene.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const helper = new THREE.DirectionalLightHelper(light);
- scene.add(helper);
- </pre>
- <p>While we're at it let's make it so we can set both the position
- of the light and the target. To do this we'll make a function
- that given a <a href="/docs/#api/en/math/Vector3"><code class="notranslate" translate="no">Vector3</code></a> will adjust its <code class="notranslate" translate="no">x</code>, <code class="notranslate" translate="no">y</code>, and <code class="notranslate" translate="no">z</code> properties
- using <code class="notranslate" translate="no">lil-gui</code>.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">function makeXYZGUI(gui, vector3, name, onChangeFn) {
- const folder = gui.addFolder(name);
- folder.add(vector3, 'x', -10, 10).onChange(onChangeFn);
- folder.add(vector3, 'y', 0, 10).onChange(onChangeFn);
- folder.add(vector3, 'z', -10, 10).onChange(onChangeFn);
- folder.open();
- }
- </pre>
- <p>Note that we need to call the helper's <code class="notranslate" translate="no">update</code> function
- anytime we change something so the helper knows to update
- itself. As such we pass in an <code class="notranslate" translate="no">onChangeFn</code> function to
- get called anytime lil-gui updates a value.</p>
- <p>Then we can use that for both the light's position
- and the target's position like this</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">+function updateLight() {
- + light.target.updateMatrixWorld();
- + helper.update();
- +}
- +updateLight();
- const gui = new GUI();
- gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
- gui.add(light, 'intensity', 0, 2, 0.01);
- +makeXYZGUI(gui, light.position, 'position', updateLight);
- +makeXYZGUI(gui, light.target.position, 'target', updateLight);
- </pre>
- <p>Now we can move the light, and its target</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/lights-directional-w-helper.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-directional-w-helper.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>Orbit the camera and it gets easier to see. The plane
- represents a <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> because a directional
- light computes light coming in one direction. There is no
- <em>point</em> the light comes from, it's an infinite plane of light
- shooting out parallel rays of light.</p>
- <h2 id="-pointlight-"><a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a></h2>
- <p>A <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a> is a light that sits at a point and shoots light
- in all directions from that point. Let's change the code.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const color = 0xFFFFFF;
- -const intensity = 1;
- +const intensity = 150;
- -const light = new THREE.DirectionalLight(color, intensity);
- +const light = new THREE.PointLight(color, intensity);
- light.position.set(0, 10, 0);
- -light.target.position.set(-5, 0, 0);
- scene.add(light);
- -scene.add(light.target);
- </pre>
- <p>Let's also switch to a <a href="/docs/#api/en/helpers/PointLightHelper"><code class="notranslate" translate="no">PointLightHelper</code></a></p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">-const helper = new THREE.DirectionalLightHelper(light);
- +const helper = new THREE.PointLightHelper(light);
- scene.add(helper);
- </pre>
- <p>and as there is no target the <code class="notranslate" translate="no">onChange</code> function can be simpler.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">function updateLight() {
- - light.target.updateMatrixWorld();
- helper.update();
- }
- -updateLight();
- </pre>
- <p>Note that at some level a <a href="/docs/#api/en/helpers/PointLightHelper"><code class="notranslate" translate="no">PointLightHelper</code></a> has no um, point.
- It just draws a small wireframe diamond. It could just as easily
- be any shape you want, just add a mesh to the light itself.</p>
- <p>A <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a> has the added property of <a href="/docs/#api/en/lights/PointLight#distance"><code class="notranslate" translate="no">distance</code></a>.
- If the <code class="notranslate" translate="no">distance</code> is 0 then the <a href="/docs/#api/en/lights/PointLight"><code class="notranslate" translate="no">PointLight</code></a> shines to
- infinity. If the <code class="notranslate" translate="no">distance</code> is greater than 0 then the light shines
- its full intensity at the light and fades to no influence at <code class="notranslate" translate="no">distance</code>
- units away from the light.</p>
- <p>Let's setup the GUI so we can adjust the distance.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const gui = new GUI();
- gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
- gui.add(light, 'intensity', 0, 2, 0.01);
- +gui.add(light, 'distance', 0, 40).onChange(updateLight);
- makeXYZGUI(gui, light.position, 'position', updateLight);
- -makeXYZGUI(gui, light.target.position, 'target', updateLight);
- </pre>
- <p>And now try it out.</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/lights-point.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-point.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>Notice when <code class="notranslate" translate="no">distance</code> is > 0 how the light fades out.</p>
- <h2 id="-spotlight-"><a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a></h2>
- <p>Spotlights are effectively a point light with a cone
- attached where the light only shines inside the cone.
- There's actually 2 cones. An outer cone and an inner
- cone. Between the inner cone and the outer cone the
- light fades from full intensity to zero.</p>
- <p>To use a <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a> we need a target just like
- the directional light. The light's cone will
- open toward the target.</p>
- <p>Modifying our <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> with helper from above</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const color = 0xFFFFFF;
- -const intensity = 1;
- +const intensity = 150;
- -const light = new THREE.DirectionalLight(color, intensity);
- +const light = new THREE.SpotLight(color, intensity);
- scene.add(light);
- scene.add(light.target);
- -const helper = new THREE.DirectionalLightHelper(light);
- +const helper = new THREE.SpotLightHelper(light);
- scene.add(helper);
- </pre>
- <p>The spotlight's cone's angle is set with the <a href="/docs/#api/en/lights/SpotLight#angle"><code class="notranslate" translate="no">angle</code></a>
- property in radians. We'll use our <code class="notranslate" translate="no">DegRadHelper</code> from the
- <a href="textures.html">texture article</a> to present a UI in
- degrees.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">gui.add(new DegRadHelper(light, 'angle'), 'value', 0, 90).name('angle').onChange(updateLight);
- </pre>
- <p>The inner cone is defined by setting the <a href="/docs/#api/en/lights/SpotLight#penumbra"><code class="notranslate" translate="no">penumbra</code></a> property
- as a percentage from the outer cone. In other words when <code class="notranslate" translate="no">penumbra</code> is 0 then the
- inner cone is the same size (0 = no difference) from the outer cone. When the
- <code class="notranslate" translate="no">penumbra</code> is 1 then the light fades starting in the center of the cone to the
- outer cone. When <code class="notranslate" translate="no">penumbra</code> is .5 then the light fades starting from 50% between
- the center of the outer cone.</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">gui.add(light, 'penumbra', 0, 1, 0.01);
- </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/lights-spot-w-helper.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-spot-w-helper.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>Notice with the default <code class="notranslate" translate="no">penumbra</code> of 0 the spotlight has a very sharp edge
- whereas as you adjust the <code class="notranslate" translate="no">penumbra</code> toward 1 the edge blurs.</p>
- <p>It might be hard to see the <em>cone</em> of the spotlight. The reason is it's
- below the ground. Shorten the distance to around 5 and you'll see the open
- end of the cone.</p>
- <h2 id="-rectarealight-"><a href="/docs/#api/en/lights/RectAreaLight"><code class="notranslate" translate="no">RectAreaLight</code></a></h2>
- <p>There's one more type of light, the <a href="/docs/#api/en/lights/RectAreaLight"><code class="notranslate" translate="no">RectAreaLight</code></a>, which represents
- exactly what it sounds like, a rectangular area of light like a long
- fluorescent light or maybe a frosted sky light in a ceiling.</p>
- <p>The <a href="/docs/#api/en/lights/RectAreaLight"><code class="notranslate" translate="no">RectAreaLight</code></a> only works with the <a href="/docs/#api/en/materials/MeshStandardMaterial"><code class="notranslate" translate="no">MeshStandardMaterial</code></a> and the
- <a href="/docs/#api/en/materials/MeshPhysicalMaterial"><code class="notranslate" translate="no">MeshPhysicalMaterial</code></a> so let's change all our materials to <a href="/docs/#api/en/materials/MeshStandardMaterial"><code class="notranslate" translate="no">MeshStandardMaterial</code></a></p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no"> ...
- const planeGeo = new THREE.PlaneGeometry(planeSize, planeSize);
- - const planeMat = new THREE.MeshPhongMaterial({
- + const planeMat = new THREE.MeshStandardMaterial({
- map: texture,
- side: THREE.DoubleSide,
- });
- const mesh = new THREE.Mesh(planeGeo, planeMat);
- mesh.rotation.x = Math.PI * -.5;
- scene.add(mesh);
- }
- {
- const cubeSize = 4;
- const cubeGeo = new THREE.BoxGeometry(cubeSize, cubeSize, cubeSize);
- - const cubeMat = new THREE.MeshPhongMaterial({color: '#8AC'});
- + const cubeMat = new THREE.MeshStandardMaterial({color: '#8AC'});
- const mesh = new THREE.Mesh(cubeGeo, cubeMat);
- mesh.position.set(cubeSize + 1, cubeSize / 2, 0);
- scene.add(mesh);
- }
- {
- const sphereRadius = 3;
- const sphereWidthDivisions = 32;
- const sphereHeightDivisions = 16;
- const sphereGeo = new THREE.SphereGeometry(sphereRadius, sphereWidthDivisions, sphereHeightDivisions);
- - const sphereMat = new THREE.MeshPhongMaterial({color: '#CA8'});
- + const sphereMat = new THREE.MeshStandardMaterial({color: '#CA8'});
- const mesh = new THREE.Mesh(sphereGeo, sphereMat);
- mesh.position.set(-sphereRadius - 1, sphereRadius + 2, 0);
- scene.add(mesh);
- }
- </pre>
- <p>To use the <a href="/docs/#api/en/lights/RectAreaLight"><code class="notranslate" translate="no">RectAreaLight</code></a> we need to include some extra three.js optional data and we'll
- include the <a href="/docs/#api/en/helpers/RectAreaLightHelper"><code class="notranslate" translate="no">RectAreaLightHelper</code></a> to help us visualize the light</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">import * as THREE from 'three';
- +import {RectAreaLightUniformsLib} from 'three/addons/lights/RectAreaLightUniformsLib.js';
- +import {RectAreaLightHelper} from 'three/addons/helpers/RectAreaLightHelper.js';
- </pre>
- <p>and we need to call <code class="notranslate" translate="no">RectAreaLightUniformsLib.init</code></p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">function main() {
- const canvas = document.querySelector('#c');
- const renderer = new THREE.WebGLRenderer({antialias: true, canvas});
- + RectAreaLightUniformsLib.init();
- </pre>
- <p>If you forget the data the light will still work but it will look funny so
- be sure to remember to include the extra data.</p>
- <p>Now we can create the light</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const color = 0xFFFFFF;
- *const intensity = 5;
- +const width = 12;
- +const height = 4;
- *const light = new THREE.RectAreaLight(color, intensity, width, height);
- light.position.set(0, 10, 0);
- +light.rotation.x = THREE.MathUtils.degToRad(-90);
- scene.add(light);
- *const helper = new RectAreaLightHelper(light);
- *light.add(helper);
- </pre>
- <p>One thing to notice is that unlike the <a href="/docs/#api/en/lights/DirectionalLight"><code class="notranslate" translate="no">DirectionalLight</code></a> and the <a href="/docs/#api/en/lights/SpotLight"><code class="notranslate" translate="no">SpotLight</code></a>, the
- <a href="/docs/#api/en/lights/RectAreaLight"><code class="notranslate" translate="no">RectAreaLight</code></a> does not use a target. It just uses its rotation. Another thing
- to notice is the helper needs to be a child of the light. It is not a child of the
- scene like other helpers.</p>
- <p>Let's also adjust the GUI. We'll make it so we can rotate the light and adjust
- its <code class="notranslate" translate="no">width</code> and <code class="notranslate" translate="no">height</code></p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const gui = new GUI();
- gui.addColor(new ColorGUIHelper(light, 'color'), 'value').name('color');
- gui.add(light, 'intensity', 0, 10, 0.01);
- gui.add(light, 'width', 0, 20);
- gui.add(light, 'height', 0, 20);
- gui.add(new DegRadHelper(light.rotation, 'x'), 'value', -180, 180).name('x rotation');
- gui.add(new DegRadHelper(light.rotation, 'y'), 'value', -180, 180).name('y rotation');
- gui.add(new DegRadHelper(light.rotation, 'z'), 'value', -180, 180).name('z rotation');
- makeXYZGUI(gui, light.position, 'position');
- </pre>
- <p>And here is that.</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/lights-rectarea.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/lights-rectarea.html" target="_blank">click here to open in a separate window</a>
- </div>
- <p></p>
- <p>It's important to note each light you add to the scene slows down how fast
- three.js renders the scene so you should always try to use as few as
- possible to achieve your goals.</p>
- <p>Next up let's go over <a href="cameras.html">dealing with cameras</a>.</p>
- <p><canvas id="c"></canvas></p>
- <script type="module" src="../resources/threejs-lights.js"></script>
- </div>
- </div>
- </div>
- <script src="../resources/prettify.js"></script>
- <script src="../resources/lesson.js"></script>
- </body></html>
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