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- <title>自定义缓冲几何体</title>
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- <h1>自定义缓冲几何体</h1>
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- <div class="lesson">
- <div class="lesson-main">
- <p>在three.js中, <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 是用来代表所有几何体的一种方式。 <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 本质上是一系列 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a>s 的 <em>名称</em> 。每一个 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a> 代表一种类型数据的数组:位置,法线,颜色,uv,等等…… 这些合起来, <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a>s 代表每个顶点所有数据的 <em>并行数组</em> 。</p>
- <div class="threejs_center"><img src="../resources/threejs-attributes.svg" style="width: 700px"></div>
- <p>上面提到,我们有四个属性:<code class="notranslate" translate="no">position</code>, <code class="notranslate" translate="no">normal</code>, <code class="notranslate" translate="no">color</code>, <code class="notranslate" translate="no">uv</code> 。
- 它们指的是 <em>并行数组</em> ,代表每个属性的第N个数据集属于同一个顶点。index=4的顶点被高亮表示贯穿所有属性的平行数据定义一个顶点。</p>
- <p>这就告诉我们,这是一个方块的数据图,高亮的地方代表一个角。</p>
- <div class="threejs_center"><img src="../resources/cube-faces-vertex.svg" style="width: 500px"></div>
- <p>考虑下方块的单个角,不同的面都需要一个不同的法线。法线是面朝向的信息。在图中,在方块的角周围用箭头表示的法线,代表共用顶点位置的面需要指向不同方向的法线。</p>
- <p>同理,一个角在不同的面需要不同的UVs。UVs是用来指定纹理区域中,画在相应顶点位置三角形的纹理坐标。你可以看到,绿色的面需要顶点的UV对应于F纹理的右上角,蓝色的面需要的UV对应于F纹理的左上角,红色的面需要的UV对应于F纹理的左下角。</p>
- <p>一个简单的 <em>顶点</em> 是所有组成部分的集合。如果顶点需要其中任一部分变得不同,那么它必须是一个不同的顶点。</p>
- <p>举一个简单的例子,让我们创建一个使用 <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 的方块。方块很有趣,因为它看起来在角的地方共用顶点但实际上不是。在我们的例子中,我们将列出所有顶点数据,然后转化成并行数组,最后用它们创建 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a>s 并添加到 <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 。</p>
- <p>我们从方块所需的所有数据开始。再次记住如果顶点有任何独一无二的部分,它必须是不同的顶点。像这里创建一个方块需要36个顶点,每个面2个三角形,每个三角形3个顶点,6个面=36个顶点。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const vertices = [
- // front
- { pos: [-1, -1, 1], norm: [ 0, 0, 1], uv: [0, 0], },
- { pos: [ 1, -1, 1], norm: [ 0, 0, 1], uv: [1, 0], },
- { pos: [-1, 1, 1], norm: [ 0, 0, 1], uv: [0, 1], },
- { pos: [-1, 1, 1], norm: [ 0, 0, 1], uv: [0, 1], },
- { pos: [ 1, -1, 1], norm: [ 0, 0, 1], uv: [1, 0], },
- { pos: [ 1, 1, 1], norm: [ 0, 0, 1], uv: [1, 1], },
- // right
- { pos: [ 1, -1, 1], norm: [ 1, 0, 0], uv: [0, 0], },
- { pos: [ 1, -1, -1], norm: [ 1, 0, 0], uv: [1, 0], },
- { pos: [ 1, 1, 1], norm: [ 1, 0, 0], uv: [0, 1], },
- { pos: [ 1, 1, 1], norm: [ 1, 0, 0], uv: [0, 1], },
- { pos: [ 1, -1, -1], norm: [ 1, 0, 0], uv: [1, 0], },
- { pos: [ 1, 1, -1], norm: [ 1, 0, 0], uv: [1, 1], },
- // back
- { pos: [ 1, -1, -1], norm: [ 0, 0, -1], uv: [0, 0], },
- { pos: [-1, -1, -1], norm: [ 0, 0, -1], uv: [1, 0], },
- { pos: [ 1, 1, -1], norm: [ 0, 0, -1], uv: [0, 1], },
- { pos: [ 1, 1, -1], norm: [ 0, 0, -1], uv: [0, 1], },
- { pos: [-1, -1, -1], norm: [ 0, 0, -1], uv: [1, 0], },
- { pos: [-1, 1, -1], norm: [ 0, 0, -1], uv: [1, 1], },
- // left
- { pos: [-1, -1, -1], norm: [-1, 0, 0], uv: [0, 0], },
- { pos: [-1, -1, 1], norm: [-1, 0, 0], uv: [1, 0], },
- { pos: [-1, 1, -1], norm: [-1, 0, 0], uv: [0, 1], },
- { pos: [-1, 1, -1], norm: [-1, 0, 0], uv: [0, 1], },
- { pos: [-1, -1, 1], norm: [-1, 0, 0], uv: [1, 0], },
- { pos: [-1, 1, 1], norm: [-1, 0, 0], uv: [1, 1], },
- // top
- { pos: [ 1, 1, -1], norm: [ 0, 1, 0], uv: [0, 0], },
- { pos: [-1, 1, -1], norm: [ 0, 1, 0], uv: [1, 0], },
- { pos: [ 1, 1, 1], norm: [ 0, 1, 0], uv: [0, 1], },
- { pos: [ 1, 1, 1], norm: [ 0, 1, 0], uv: [0, 1], },
- { pos: [-1, 1, -1], norm: [ 0, 1, 0], uv: [1, 0], },
- { pos: [-1, 1, 1], norm: [ 0, 1, 0], uv: [1, 1], },
- // bottom
- { pos: [ 1, -1, 1], norm: [ 0, -1, 0], uv: [0, 0], },
- { pos: [-1, -1, 1], norm: [ 0, -1, 0], uv: [1, 0], },
- { pos: [ 1, -1, -1], norm: [ 0, -1, 0], uv: [0, 1], },
- { pos: [ 1, -1, -1], norm: [ 0, -1, 0], uv: [0, 1], },
- { pos: [-1, -1, 1], norm: [ 0, -1, 0], uv: [1, 0], },
- { pos: [-1, -1, -1], norm: [ 0, -1, 0], uv: [1, 1], },
- ];
- </pre>
- <p>然后我们能将它们全部转换成3个并行数组</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const positions = [];
- const normals = [];
- const uvs = [];
- for (const vertex of vertices) {
- positions.push(...vertex.pos);
- normals.push(...vertex.norm);
- uvs.push(...vertex.uv);
- }
- </pre>
- <p>最终我们能创建一个 <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> ,然后为每个数组创建一个 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a> 并添加到 <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no"> const geometry = new THREE.BufferGeometry();
- const positionNumComponents = 3;
- const normalNumComponents = 3;
- const uvNumComponents = 2;
- geometry.setAttribute(
- 'position',
- new THREE.BufferAttribute(new Float32Array(positions), positionNumComponents));
- geometry.setAttribute(
- 'normal',
- new THREE.BufferAttribute(new Float32Array(normals), normalNumComponents));
- geometry.setAttribute(
- 'uv',
- new THREE.BufferAttribute(new Float32Array(uvs), uvNumComponents));
- </pre>
- <p>注意名字很重要。你必须将属性的名字命名成three.js所期望的(除非你正在创建自定义着色器),在这里是 <code class="notranslate" translate="no">position</code>、 <code class="notranslate" translate="no">normal</code> 和 <code class="notranslate" translate="no">uv</code> 。如果你想要设置顶点颜色则命名属性为 <code class="notranslate" translate="no">color</code> 。</p>
- <p>在上面我们创建了3个JavaScript原生数组, <code class="notranslate" translate="no">positions</code>, <code class="notranslate" translate="no">normals</code> 和 <code class="notranslate" translate="no">uvs</code> 。
- 然后我们将他们转换为 <code class="notranslate" translate="no">Float32Array</code> 的类型数组<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray">TypedArrays</a>。 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a> 是类型数组而不是原生数组。同时 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a> 需要你设定每个顶点有多少组成成分。对于位置和法线,每个顶点我们需要3个组成成分,x、y和z。对于UVs我们需要2个,u和v。</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/custom-buffergeometry-cube.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/custom-buffergeometry-cube.html" target="_blank">点击此处在新标签页中打开</a>
- </div>
- <p></p>
- <p>那会是大量的数据。我们可以做点改善,可以用索引来代表顶点。看回我们的方块数据,每个面由2个三角形组成,每个三角形3个顶点,总共6个,但是其中2个是完全一样的;同样的位置,同样的法线,和同样的uv。因此,我们可以移除匹配的顶点,然后用索引代表他们。首先我们移除匹配的顶点。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const vertices = [
- // front
- { pos: [-1, -1, 1], norm: [ 0, 0, 1], uv: [0, 0], }, // 0
- { pos: [ 1, -1, 1], norm: [ 0, 0, 1], uv: [1, 0], }, // 1
- { pos: [-1, 1, 1], norm: [ 0, 0, 1], uv: [0, 1], }, // 2
- -
- - { pos: [-1, 1, 1], norm: [ 0, 0, 1], uv: [0, 1], },
- - { pos: [ 1, -1, 1], norm: [ 0, 0, 1], uv: [1, 0], },
- { pos: [ 1, 1, 1], norm: [ 0, 0, 1], uv: [1, 1], }, // 3
- // right
- { pos: [ 1, -1, 1], norm: [ 1, 0, 0], uv: [0, 0], }, // 4
- { pos: [ 1, -1, -1], norm: [ 1, 0, 0], uv: [1, 0], }, // 5
- -
- - { pos: [ 1, 1, 1], norm: [ 1, 0, 0], uv: [0, 1], },
- - { pos: [ 1, -1, -1], norm: [ 1, 0, 0], uv: [1, 0], },
- { pos: [ 1, 1, 1], norm: [ 1, 0, 0], uv: [0, 1], }, // 6
- { pos: [ 1, 1, -1], norm: [ 1, 0, 0], uv: [1, 1], }, // 7
- // back
- { pos: [ 1, -1, -1], norm: [ 0, 0, -1], uv: [0, 0], }, // 8
- { pos: [-1, -1, -1], norm: [ 0, 0, -1], uv: [1, 0], }, // 9
- -
- - { pos: [ 1, 1, -1], norm: [ 0, 0, -1], uv: [0, 1], },
- - { pos: [-1, -1, -1], norm: [ 0, 0, -1], uv: [1, 0], },
- { pos: [ 1, 1, -1], norm: [ 0, 0, -1], uv: [0, 1], }, // 10
- { pos: [-1, 1, -1], norm: [ 0, 0, -1], uv: [1, 1], }, // 11
- // left
- { pos: [-1, -1, -1], norm: [-1, 0, 0], uv: [0, 0], }, // 12
- { pos: [-1, -1, 1], norm: [-1, 0, 0], uv: [1, 0], }, // 13
- -
- - { pos: [-1, 1, -1], norm: [-1, 0, 0], uv: [0, 1], },
- - { pos: [-1, -1, 1], norm: [-1, 0, 0], uv: [1, 0], },
- { pos: [-1, 1, -1], norm: [-1, 0, 0], uv: [0, 1], }, // 14
- { pos: [-1, 1, 1], norm: [-1, 0, 0], uv: [1, 1], }, // 15
- // top
- { pos: [ 1, 1, -1], norm: [ 0, 1, 0], uv: [0, 0], }, // 16
- { pos: [-1, 1, -1], norm: [ 0, 1, 0], uv: [1, 0], }, // 17
- -
- - { pos: [ 1, 1, 1], norm: [ 0, 1, 0], uv: [0, 1], },
- - { pos: [-1, 1, -1], norm: [ 0, 1, 0], uv: [1, 0], },
- { pos: [ 1, 1, 1], norm: [ 0, 1, 0], uv: [0, 1], }, // 18
- { pos: [-1, 1, 1], norm: [ 0, 1, 0], uv: [1, 1], }, // 19
- // bottom
- { pos: [ 1, -1, 1], norm: [ 0, -1, 0], uv: [0, 0], }, // 20
- { pos: [-1, -1, 1], norm: [ 0, -1, 0], uv: [1, 0], }, // 21
- -
- - { pos: [ 1, -1, -1], norm: [ 0, -1, 0], uv: [0, 1], },
- - { pos: [-1, -1, 1], norm: [ 0, -1, 0], uv: [1, 0], },
- { pos: [ 1, -1, -1], norm: [ 0, -1, 0], uv: [0, 1], }, // 22
- { pos: [-1, -1, -1], norm: [ 0, -1, 0], uv: [1, 1], }, // 23
- ];
- </pre>
- <p>现在我们有24个唯一的顶点。然后我们为36个要画的顶点设定36个索引,通过调用 <a href="/docs/#api/zh/core/BufferGeometry.setIndex"><code class="notranslate" translate="no">BufferGeometry.setIndex</code></a> 并传入索引数组来创建12个三角形。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">geometry.setAttribute(
- 'position',
- new THREE.BufferAttribute(positions, positionNumComponents));
- geometry.setAttribute(
- 'normal',
- new THREE.BufferAttribute(normals, normalNumComponents));
- geometry.setAttribute(
- 'uv',
- new THREE.BufferAttribute(uvs, uvNumComponents));
- +geometry.setIndex([
- + 0, 1, 2, 2, 1, 3, // front
- + 4, 5, 6, 6, 5, 7, // right
- + 8, 9, 10, 10, 9, 11, // back
- + 12, 13, 14, 14, 13, 15, // left
- + 16, 17, 18, 18, 17, 19, // top
- + 20, 21, 22, 22, 21, 23, // bottom
- +]);
- </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/custom-buffergeometry-cube-indexed.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/custom-buffergeometry-cube-indexed.html" target="_blank">点击此处在新标签页中打开</a>
- </div>
- <p></p>
- <p>如果你没有提供法线数据的话, <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 有个方法<a href="/docs/#api/zh/core/BufferGeometry#computeVertexNormals"><code class="notranslate" translate="no">computeVertexNormals</code></a>可以用来计算法线。不幸的是,因为如果顶点的其他数据不同的话,位置数据不能被共享,调用 <code class="notranslate" translate="no">computeVertexNormals</code> 会让你的几何体像球面或者圆筒一样连接自身。</p>
- <div class="spread">
- <div>
- <div data-diagram="bufferGeometryCylinder"></div>
- </div>
- </div>
- <p>对于上面的圆筒,法线是通过 <code class="notranslate" translate="no">computeVertexNormals</code> 方法创建的。
- 如果你仔细观察会发现在圆筒上有条缝。这是因为在圆筒的开始和结束的地方没有办法共享顶点数据,需要不同的UVs,所以该方法不知道它们是同样的顶点以平滑过度。只要知道一点,解决方法是应用自己的法线数据。</p>
- <p>我们同样可以在一开始使用类型数组<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray">TypedArrays</a>取代JavaScript的原生数组。
- 缺点是你必须在一开始定义数组的大小。当然那不是很难,但是使用原生数组我们只需要用 <code class="notranslate" translate="no">push</code> 将数据加入数组并最后通过 <code class="notranslate" translate="no">length</code> 查看数组大小。使用类型数组我们没有这样的方法,所以需要记录添加的数据。</p>
- <p>在这个例子,提前计算数组长度很简单,因为我们一开始使用一大块静态数据。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">-const positions = [];
- -const normals = [];
- -const uvs = [];
- +const numVertices = vertices.length;
- +const positionNumComponents = 3;
- +const normalNumComponents = 3;
- +const uvNumComponents = 2;
- +const positions = new Float32Array(numVertices * positionNumComponents);
- +const normals = new Float32Array(numVertices * normalNumComponents);
- +const uvs = new Float32Array(numVertices * uvNumComponents);
- +let posNdx = 0;
- +let nrmNdx = 0;
- +let uvNdx = 0;
- for (const vertex of vertices) {
- - positions.push(...vertex.pos);
- - normals.push(...vertex.norm);
- - uvs.push(...vertex.uv);
- + positions.set(vertex.pos, posNdx);
- + normals.set(vertex.norm, nrmNdx);
- + uvs.set(vertex.uv, uvNdx);
- + posNdx += positionNumComponents;
- + nrmNdx += normalNumComponents;
- + uvNdx += uvNumComponents;
- }
- geometry.setAttribute(
- 'position',
- - new THREE.BufferAttribute(new Float32Array(positions), positionNumComponents));
- + new THREE.BufferAttribute(positions, positionNumComponents));
- geometry.setAttribute(
- 'normal',
- - new THREE.BufferAttribute(new Float32Array(normals), normalNumComponents));
- + new THREE.BufferAttribute(normals, normalNumComponents));
- geometry.setAttribute(
- 'uv',
- - new THREE.BufferAttribute(new Float32Array(uvs), uvNumComponents));
- + new THREE.BufferAttribute(uvs, uvNumComponents));
- geometry.setIndex([
- 0, 1, 2, 2, 1, 3, // front
- 4, 5, 6, 6, 5, 7, // right
- 8, 9, 10, 10, 9, 11, // back
- 12, 13, 14, 14, 13, 15, // left
- 16, 17, 18, 18, 17, 19, // top
- 20, 21, 22, 22, 21, 23, // bottom
- ]);
- </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/custom-buffergeometry-cube-typedarrays.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/custom-buffergeometry-cube-typedarrays.html" target="_blank">点击此处在新标签页中打开</a>
- </div>
- <p></p>
- <p>一个使用类型数组的好理由,是如果你想动态更新顶点数据的任何一部分。</p>
- <p>因为想不起动态更新顶点数据的好例子,所以我决定创建一个球面并从中央开始进进出出地移动每个四边形。但愿它是个有用的例子。</p>
- <p>这里是用来产生球面的位置和索引数据的代码。代码共享了四边形内的顶点数据,但是四边形之间的没有共享,因为我们需要分别地移动每个四边形。</p>
- <p>因为我懒,所以我通过3个 <a href="/docs/#api/zh/core/Object3D"><code class="notranslate" translate="no">Object3D</code></a> 对象的层级关系,计算球面的点。关于如何计算在这篇文章有解释<a href="optimize-lots-of-objects.html">the article on optimizing lots of objects</a>。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">function makeSpherePositions(segmentsAround, segmentsDown) {
- const numVertices = segmentsAround * segmentsDown * 6;
- const numComponents = 3;
- const positions = new Float32Array(numVertices * numComponents);
- const indices = [];
- const longHelper = new THREE.Object3D();
- const latHelper = new THREE.Object3D();
- const pointHelper = new THREE.Object3D();
- longHelper.add(latHelper);
- latHelper.add(pointHelper);
- pointHelper.position.z = 1;
- const temp = new THREE.Vector3();
- function getPoint(lat, long) {
- latHelper.rotation.x = lat;
- longHelper.rotation.y = long;
- longHelper.updateMatrixWorld(true);
- return pointHelper.getWorldPosition(temp).toArray();
- }
- let posNdx = 0;
- let ndx = 0;
- for (let down = 0; down < segmentsDown; ++down) {
- const v0 = down / segmentsDown;
- const v1 = (down + 1) / segmentsDown;
- const lat0 = (v0 - 0.5) * Math.PI;
- const lat1 = (v1 - 0.5) * Math.PI;
- for (let across = 0; across < segmentsAround; ++across) {
- const u0 = across / segmentsAround;
- const u1 = (across + 1) / segmentsAround;
- const long0 = u0 * Math.PI * 2;
- const long1 = u1 * Math.PI * 2;
- positions.set(getPoint(lat0, long0), posNdx); posNdx += numComponents;
- positions.set(getPoint(lat1, long0), posNdx); posNdx += numComponents;
- positions.set(getPoint(lat0, long1), posNdx); posNdx += numComponents;
- positions.set(getPoint(lat1, long1), posNdx); posNdx += numComponents;
- indices.push(
- ndx, ndx + 1, ndx + 2,
- ndx + 2, ndx + 1, ndx + 3,
- );
- ndx += 4;
- }
- }
- return {positions, indices};
- }
- </pre>
- <p>然后我们像这样调用。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const segmentsAround = 24;
- const segmentsDown = 16;
- const {positions, indices} = makeSpherePositions(segmentsAround, segmentsDown);
- </pre>
- <p>因为返回的位置数据是单位球面位置,所以它们跟我们需要的法线数据完全一样,我们只需要复制它们。</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const normals = positions.slice();
- </pre>
- <p>然后我们像之前一样设置属性</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const geometry = new THREE.BufferGeometry();
- const positionNumComponents = 3;
- const normalNumComponents = 3;
- +const positionAttribute = new THREE.BufferAttribute(positions, positionNumComponents);
- +positionAttribute.setUsage(THREE.DynamicDrawUsage);
- geometry.setAttribute(
- 'position',
- + positionAttribute);
- geometry.setAttribute(
- 'normal',
- new THREE.BufferAttribute(normals, normalNumComponents));
- geometry.setIndex(indices);
- </pre>
- <p>我已经高亮一些区别。我们保存了位置属性的引用。
- 同时我们标记它为动态。这是提示THREE.js我们将会经常改变属性的内容。</p>
- <p>在我们的渲染循环中,每一帧我们基于它们的法线更新位置</p>
- <pre class="prettyprint showlinemods notranslate lang-js" translate="no">const temp = new THREE.Vector3();
- ...
- for (let i = 0; i < positions.length; i += 3) {
- const quad = (i / 12 | 0);
- const ringId = quad / segmentsAround | 0;
- const ringQuadId = quad % segmentsAround;
- const ringU = ringQuadId / segmentsAround;
- const angle = ringU * Math.PI * 2;
- temp.fromArray(normals, i);
- temp.multiplyScalar(THREE.MathUtils.lerp(1, 1.4, Math.sin(time + ringId + angle) * .5 + .5));
- temp.toArray(positions, i);
- }
- positionAttribute.needsUpdate = true;
- </pre>
- <p>我们设置 <code class="notranslate" translate="no">positionAttribute.needsUpdate</code> 告诉THREE.js更新我们的改变。</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/custom-buffergeometry-dynamic.html"></iframe></div>
- <a class="threejs_center" href="/manual/examples/custom-buffergeometry-dynamic.html" target="_blank">点击此处在新标签页中打开</a>
- </div>
- <p></p>
- <p>我希望这些例子能对如何使用 <a href="/docs/#api/zh/core/BufferGeometry"><code class="notranslate" translate="no">BufferGeometry</code></a> 直接创建你自己的几何体和如何动态更新 <a href="/docs/#api/zh/core/BufferAttribute"><code class="notranslate" translate="no">BufferAttribute</code></a> 的内容发挥作用。</p>
- <!-- needed in English only to prevent warning from outdated translations -->
- <p><a href="resources/threejs-geometry.svg"></a></p>
- <p><canvas id="c"></canvas></p>
- <script type="module" src="../resources/threejs-custom-buffergeometry.js"></script>
- </div>
- </div>
- </div>
- <script src="../resources/prettify.js"></script>
- <script src="../resources/lesson.js"></script>
- </body></html>
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