Three.js - 绘制线条

您已经了解了 Three.js 中相当多的材质。现在让我们看看一些用于绘制线条的独特材质。我们可以使用线条绘制各种形状和图案。

使用 BufferGeometry

THREE.BufferGeometry 是 Three.js 中所有内置几何体的基类。您可以通过传递几何体顶点数组来创建自己的几何体。

了解更多关于 BufferGeometry 的信息这里。

const points = []
points.push(new THREE.Vector3(-10, 0, 0))
points.push(new THREE.Vector3(0, -10, 0))
points.push(new THREE.Vector3(10, 0, 0))

这些是 Three.js 提供给我们创建几何体的一些额外元素。THREE.Vector3(x, y, z) - 它在 3D 空间中创建一个点。在上面的代码中，我们将 3 个点添加到 points 数组中。

const geometry = new THREE.BufferGeometry().setFromPoints(points)

THREE.BufferGeometry()，如前所述，它创建了我们的几何体。我们使用 setFromPoints 方法使用点数组设置几何体。

注意 - 线在每个连续的顶点对之间绘制，但在第一个和最后一个顶点之间不绘制（线条未闭合）。

const material = new THREE.LineBasicMaterial({
   // for normal lines
   color: 0xffffff,
   linewidth: 1,
   linecap: 'round', //ignored by WebGLRenderer
   linejoin: 'round', //ignored by WebGLRenderer
})
// or
const material = new THREE.LineDashedMaterial({
   // for dashed lines
   color: 0xffffff,
   linewidth: 1,scale: 1,
   dashSize: 3,
   gapSize: 1,
})

这些是线条的独特材质。您可以使用 THREE.LineBasicMaterial 或 THREE.LineDashedMaterial 中的任何一个。

const line = new THREE.Line(geometry, material)

示例

现在，我们使用 THREE.Line 来绘制线条，而不是使用 THREE.Mesh。现在，您会看到屏幕上使用线条绘制的“V”形。

linebasic.html

在线演示

<!DOCTYPE html>
<html lang="en">
   <head>
      <meta charset="UTF-8" />
      <meta http-equiv="X-UA-Compatible" content="ie=edge" />
      <meta name="viewport" content="width=device-width, initial-scale=1.0" />
      <title>Three.js - Line basic</title>
      <style>
         * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: -applesystem, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu,
               Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
         }
         html,
         body {
            height: 100vh;
            width: 100vw;
         }
         #threejs-container {
            position: block;
            width: 100%;
            height: 100%;
         }
      </style>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js"></script>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/dat-gui/0.7.7/dat.gui.js"></script>
   </head>
   <body>
      <div id="threejs-container"></div>
      <script type="module">
         // Creating a line using LineBasicMaterial

         // GUI
         const gui = new dat.GUI()
         // sizes
         let width = window.innerWidth
         let height = window.innerHeight
         // scene
         const scene = new THREE.Scene()
         scene.background = new THREE.Color(0x262626)
         // camera
         const camera = new THREE.PerspectiveCamera(45, width / height, 0.1, 100)
         camera.position.set(0, 0, 50)
         camera.lookAt(0, 0, 0)
         const camFolder = gui.addFolder('Camera')
         camFolder.add(camera.position, 'z', 10, 100)
         camFolder.open()
         // Line
         const points = []
         points.push(new THREE.Vector3(-10, 0, 0))
         points.push(new THREE.Vector3(0, -20, 0))
         points.push(new THREE.Vector3(10, 0, 0))
         const folders = [gui.addFolder('Poin 1'), gui.addFolder('Poin 2'), gui.addFolder('Poin 3')]
         folders.forEach((folder, i) => {
            folder.add(points[i], 'x', -30, 30, 1).onChange(redraw)
            folder.add(points[i], 'y', -30, 30, 1).onChange(redraw)
            folder.add(points[i], 'z', -30, 30, 1).onChange(redraw)
            folder.open()
         })
         const geometry = new THREE.BufferGeometry().setFromPoints(points)
         const material = new THREE.LineBasicMaterial({
            color: 0xffffff,
            linewidth: 2
         })
         const line = new THREE.Line(geometry, material)
         line.position.set(0, 10, 0)
         scene.add(line)
         function redraw() {
            let newGeometry = new THREE.BufferGeometry().setFromPoints(points)
            line.geometry.dispose()
            line.geometry = newGeometry
         }
         // responsiveness
         window.addEventListener('resize', () => {
            width = window.innerWidth
            height = window.innerHeight
            camera.aspect = width / height
            camera.updateProjectionMatrix()
            renderer.setSize(window.innerWidth, window.innerHeight)
            renderer.render(scene, camera)
         })
         // renderer
         const renderer = new THREE.WebGL1Renderer()
         renderer.setSize(width, height)
         renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2))
         // animation
         function animate() {
            requestAnimationFrame(animate)
            renderer.render(scene, camera)
         }
         // rendering the scene
         const container = document.querySelector('#threejs-container')
         container.append(renderer.domElement)
         renderer.render(scene, camera)
         animate()
      </script>
   </body>
</html>

输出

示例

您可以通过指定顶点来创建任何类型的几何体线框。查看以下示例，我们正在绘制虚线。

dashedline.html

在线演示

<!DOCTYPE html>
<html lang="en">
   <head>
      <meta charset="UTF-8" />
      <meta http-equiv="X-UA-Compatible" content="ie=edge" />
      <meta name="viewport" content="width=device-width, initial-scale=1.0" />
      <title>Three.js - Dashed line</title>
      <style>
         * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: -applesystem, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu,
               Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
         }
         html,
         body {
            height: 100vh;
            width: 100vw;
         }
         #threejs-container {
            position: block;
            width: 100%;
            height: 100%;
         }
      </style>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js"></script>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/dat-gui/0.7.7/dat.gui.js"></script>
   </head>
   <body>
      <div id="threejs-container"></div>
      <script type="module">
         // Creating dashed line using LineDashedMaterial
         // GUI
         const gui = new dat.GUI()
         // sizes
         let width = window.innerWidth
         let height = window.innerHeight
         // scene
         const scene = new THREE.Scene()
         scene.background = new THREE.Color(0x262626)
         // camera
         const camera = new THREE.PerspectiveCamera(45, width / height, 0.1, 100)
         camera.position.set(0, 0, 50)
         camera.lookAt(0, 0, 0)
         const camFolder = gui.addFolder('Camera')
         camFolder.add(camera.position, 'z', 10, 100)
         camFolder.open()
         // Line
         const points = []
         points.push(new THREE.Vector3(-10, 0, 0))
         points.push(new THREE.Vector3(0, -20, 0))
         points.push(new THREE.Vector3(10, 0, 0))
         const folders = [gui.addFolder('Poin 1'), gui.addFolder('Poin 2'), gui.addFolder('Poin 3')]
         folders.forEach((folder, i) => {
            folder.add(points[i], 'x', -30, 30, 1).onChange(redraw)
            folder.add(points[i], 'y', -30, 30, 1).onChange(redraw)
            folder.add(points[i], 'z', -30, 30, 1).onChange(redraw)
            folder.open()
         })
         const geometry = new THREE.BufferGeometry().setFromPoints(points)
            const material = new THREE.LineDashedMaterial({
            color: 0xffffff,
            linewidth: 2,
            scale: 1,
            dashSize: 3,
            gapSize: 2
         })
         const line = new THREE.Line(geometry, material)
         line.computeLineDistances()
         line.position.set(0, 10, 0)
         scene.add(line)
         console.log(line)
         function redraw() {
            let newGeometry = new THREE.BufferGeometry().setFromPoints(points)
            line.geometry.dispose()
            line.geometry = newGeometry
         }
         // responsiveness
         window.addEventListener('resize', () => {
            width = window.innerWidth
            height = window.innerHeight
            camera.aspect = width / height
            camera.updateProjectionMatrix()
            renderer.setSize(window.innerWidth, window.innerHeight)
            renderer.render(scene, camera)
         })
         // renderer
         const renderer = new THREE.WebGL1Renderer()
         renderer.setSize(width, height)
         renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2))
         // animation
         function animate() {
            requestAnimationFrame(animate)
            renderer.render(scene, camera)
         }
         // rendering the scene
         const container = document.querySelector('#threejs-container')
         container.append(renderer.domElement)
         renderer.render(scene, camera)
         animate()
      </script>
   </body>
</html>

输出

打印页面