123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162 |
- <!DOCTYPE html><html lang="zh"><head>
- <meta charset="utf-8">
- <title>渲染目标</title>
- <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
- <meta name="twitter:card" content="summary_large_image">
- <meta name="twitter:site" content="@threejs">
- <meta name="twitter:title" content="Three.js – 渲染目标">
- <meta property="og:image" content="https://threejs.org/files/share.png">
- <link rel="shortcut icon" href="../../files/favicon_white.ico" media="(prefers-color-scheme: dark)">
- <link rel="shortcut icon" href="../../files/favicon.ico" media="(prefers-color-scheme: light)">
- <link rel="stylesheet" href="../resources/lesson.css">
- <link rel="stylesheet" href="../resources/lang.css">
- <script type="importmap">
- {
- "imports": {
- "three": "../../build/three.module.js"
- }
- }
- </script>
- <link rel="stylesheet" href="/manual/zh/lang.css">
- </head>
- <body>
- <div class="container">
- <div class="lesson-title">
- <h1>渲染目标</h1>
- </div>
- <div class="lesson">
- <div class="lesson-main">
- <p>在three.js中,渲染目标大体上指的是可以被渲染的纹理。当它被渲染之后,你可以像使用其他纹理一样使用它。</p>
- <p>让我们举个简单的例子。我们将从<a href="responsive.html">the article on responsiveness</a>开始。</p>
- <p>渲染到渲染目标基本上跟通常的渲染一样。首先我们创建一个 <a href="/docs/#api/zh/renderers/WebGLRenderTarget"><code class="notranslate" translate="no">WebGLRenderTarget</code></a>。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const rtWidth = 512;
- const rtHeight = 512;
- const renderTarget = new THREE.WebGLRenderTarget(rtWidth, rtHeight);
- </pre>
- <p>然后我们需要一个 <a href="/docs/#api/zh/cameras/Camera"><code class="notranslate" translate="no">Camera</code></a> 和一个 <a href="/docs/#api/zh/scenes/Scene"><code class="notranslate" translate="no">Scene</code></a></p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const rtFov = 75;
- const rtAspect = rtWidth / rtHeight;
- const rtNear = 0.1;
- const rtFar = 5;
- const rtCamera = new THREE.PerspectiveCamera(rtFov, rtAspect, rtNear, rtFar);
- rtCamera.position.z = 2;
- const rtScene = new THREE.Scene();
- rtScene.background = new THREE.Color('red');
- </pre>
- <p>注意我们设置长宽比(aspect)是相对渲染目标而言的,不是画布(canvas)。
- 正确的长宽比取决于我们要渲染的对象。在本例,我们要将渲染目标的纹理用在方块的一个面,基于方块的面我们设置长宽比为1.0。</p>
- <p>我们将需要的东西添加到场景中。在本例我们使用灯光和三个方块<a href="responsive.html">from the previous article</a>。</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(-1, 2, 4);
- * rtScene.add(light);
- }
- const boxWidth = 1;
- const boxHeight = 1;
- const boxDepth = 1;
- const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);
- function makeInstance(geometry, color, x) {
- const material = new THREE.MeshPhongMaterial({color});
- const cube = new THREE.Mesh(geometry, material);
- * rtScene.add(cube);
- cube.position.x = x;
- return cube;
- }
- *const rtCubes = [
- makeInstance(geometry, 0x44aa88, 0),
- makeInstance(geometry, 0x8844aa, -2),
- makeInstance(geometry, 0xaa8844, 2),
- ];
- </pre>
- <p>在上个例子中的 <a href="/docs/#api/zh/scenes/Scene"><code class="notranslate" translate="no">Scene</code></a> 和 <a href="/docs/#api/zh/cameras/Camera"><code class="notranslate" translate="no">Camera</code></a> 保持不变,我们将在画布中继续使用它们,只需要添加渲染的物体。</p>
- <p>让我们添加使用了渲染目标纹理的方块。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const material = new THREE.MeshPhongMaterial({
- map: renderTarget.texture,
- });
- const cube = new THREE.Mesh(geometry, material);
- scene.add(cube);
- </pre>
- <p>现在在渲染的时候,我们首先将渲染目标的场景(rtScene),渲染到渲染目标(注:这里有点绕,需要结合代码理解)。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">function render(time) {
- time *= 0.001;
- ...
- // rotate all the cubes in the render target scene
- rtCubes.forEach((cube, ndx) => {
- const speed = 1 + ndx * .1;
- const rot = time * speed;
- cube.rotation.x = rot;
- cube.rotation.y = rot;
- });
- // draw render target scene to render target
- renderer.setRenderTarget(renderTarget);
- renderer.render(rtScene, rtCamera);
- renderer.setRenderTarget(null);
- </pre>
- <p>然后我们在画布中,渲染使用了渲染目标纹理的方块的场景。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no"> // rotate the cube in the scene
- cube.rotation.x = time;
- cube.rotation.y = time * 1.1;
- // render the scene to the canvas
- renderer.render(scene, camera);
- </pre>
- <p>就是这样啦</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/render-target.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/render-target.html" target="_blank">点击此处在新标签页中打开</a>
- </div>
- <p></p>
- <p>方块是红色的,这是因为我们设置了 <code class="notranslate" translate="no">rtScene</code> 的 <code class="notranslate" translate="no">background</code> 为红色,所以渲染目标的纹理所处的背景为红色。</p>
- <p>渲染目标可以用在各种各样的物体上。<a href="shadows.html">Shadows</a>用了渲染目标,<a href="picking.html">Picking can use a render target</a>,多种效果<a href="post-processing.html">post processing effects</a>需要用到渲染目标。
- 渲染汽车的后视镜,或者3D场景中的监控实时画面,都可能用到渲染目标。</p>
- <p>关于 <a href="/docs/#api/zh/renderers/WebGLRenderTarget"><code class="notranslate" translate="no">WebGLRenderTarget</code></a> 的笔记。</p>
- <ul>
- <li><p>默认情况下 <a href="/docs/#api/zh/renderers/WebGLRenderTarget"><code class="notranslate" translate="no">WebGLRenderTarget</code></a> 会创建两个纹理。 颜色纹理和深度/模版纹理。如果你不需要深度或者模版纹理,你可以通过可选设置取消创建。例如:</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no"> const rt = new THREE.WebGLRenderTarget(width, height, {
- depthBuffer: false,
- stencilBuffer: false,
- });
- </pre>
- </li>
- <li><p>你可能需要改变渲染目标的尺寸</p>
- <p>在上面的例子,我们创建了固定尺寸512X512的渲染目标。对于像后处理,你通常需要创建跟画布一样尺寸的渲染目标。在我们的代码中意味着,当我们改变画布的尺寸,会同时更新渲染目标尺寸,和渲染目标中正在使用的摄像机。例如:</p>
- <pre class="prettyprint showlinemods notranslate notranslate" translate="no">function render(time) {
- time *= 0.001;
- if (resizeRendererToDisplaySize(renderer)) {
- const canvas = renderer.domElement;
- camera.aspect = canvas.clientWidth / canvas.clientHeight;
- camera.updateProjectionMatrix();
- + renderTarget.setSize(canvas.width, canvas.height);
- + rtCamera.aspect = camera.aspect;
- + rtCamera.updateProjectionMatrix();
- }
- </pre></li>
- </ul>
- </div>
- </div>
- </div>
- <script src="../resources/prettify.js"></script>
- <script src="../resources/lesson.js"></script>
- </body></html>
|