如何使用babylonjs或threejs预览3D中的2D平面对象？

Question

我正在使用fabricJS，并且在平面画布大小的矩形对象（基本）上几乎没有随机绘图（例如圆形，正方形，多边形）。

我想预览所有雕刻在3D主矩形对象上的图形。

他们的图书馆是否可用？我在Google上搜索了一下，发现了three.js和Babylon.js，但是其中没有类似于我的要求的示例，即使我不知道这些库是否可以实现。

现在想使用浏览器中的JS库将其转换为3D预览。

请指导我。

Answer 1

我认为，您应该使用Three.JS而不是BabylonJs，它更易于处理并且尺寸更小。

这是示例代码，也许您看起来与此类似。

您要做的就是从FabricJS中提取SVG，并将其放入ThreeJS中。

// --- Init threejs scene
// ----------------------

const scene = new THREE.Scene();

const ratio = window.innerWidth / window.innerHeight;
const renderer = new THREE.WebGLRenderer({ antialias: true });

renderer.setSize(window.innerWidth, window.innerHeight);

const camera = new THREE.PerspectiveCamera(100, ratio, 0.01, 1000);
camera.position.z = 300;

document.querySelector("body").appendChild(renderer.domElement);

// Resize and update camera
window.addEventListener('resize', function(e) {
  camera.aspect = window.innerWidth / window.innerHeight;
  camera.updateProjectionMatrix();

  renderer.setSize(window.innerWidth, window.innerHeight);
});

// Axes helper
const axesHelper = new THREE.AxesHelper(500);
scene.add(axesHelper);



// --- Main part, load and parse SVG
// ---------------------------------

const svgMarkup = document.querySelector('svg').outerHTML;

// SVG Loader is not a part of the main three.js bundle 
// We need to load it separately, it is included in this pen's Settings > JavaScript
// https://threejs.org/docs/#examples/en/loaders/SVGLoader
const loader = new THREE.SVGLoader();
const svgData = loader.parse(svgMarkup);

// Group we'll use for all SVG paths
const svgGroup = new THREE.Group();
// When importing SVGs paths are inverted on Y axis
// it happens in the process of mapping from 2d to 3d coordinate system
svgGroup.scale.y *= -1;

const material = new THREE.MeshNormalMaterial();

// Loop through all of the parsed paths
svgData.paths.forEach((path, i) => {
  const shapes = path.toShapes(true);

  // Each path has array of shapes
  shapes.forEach((shape, j) => {
    // Finally we can take each shape and extrude it
    const geometry = new THREE.ExtrudeGeometry(shape, {
      depth: 20,
      bevelEnabled: false
    });

    // Create a mesh and add it to the group
    const mesh = new THREE.Mesh(geometry, material);

    svgGroup.add(mesh);
  });
});

// Meshes we got are all relative to themselves
// meaning they have position set to (0, 0, 0)
// which makes centering them in the group easy

// Get group's size
const box = new THREE.Box3().setFromObject(svgGroup);
const size = new THREE.Vector3();
box.getSize(size);

const yOffset = size.y / -2;
const xOffset = size.x / -2;

// Offset all of group's elements, to center them
svgGroup.children.forEach(item => {
  item.position.x = xOffset;
  item.position.y = yOffset;
});

// Finally we add svg group to the scene
scene.add(svgGroup);



// --- Animation loop
// ------------------

function animate() {
  renderer.render(scene, camera);

  // Rotate out group 
  svgGroup.rotation.y += 0.005;
  
  requestAnimationFrame(animate);
}

animate();

svg {
  display: none;
}

canvas {
  display: block;
}

a {
  font-family: Helvetica, Arial, sans-serif;
  font-size: 15px;
  padding: 10px 16px;
  display: block;
  position: fixed;
  bottom: 0;
  right: 0;
  color: #ddd;
  transition: all 0.25s;
}

a:hover {
  color: #3498db;  
}

<script src="https://unpkg.com/three@0.111.0/build/three.js"></script>
<script src="https://unpkg.com/three@0.111.0/examples/js/loaders/SVGLoader.js"></script>


<svg width="202px" height="202px" viewBox="0 0 202 202" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
      <path fill="none" d="M201,1 L201,201 L1,201 L1,1 L201,1 Z M53.27053,71 L37.6666667,71 L37.6666667,134.333333 L53.27053,134.333333 L53.27053,86.6038647 C59.2367133,86.879227 66.1207733,91.1014493 66.1207733,99.9130433 L66.1207733,134.333333 L80.4396133,134.333333 L80.4396133,99.9130433 C80.4396133,91.1014493 87.32367,86.879227 93.2898567,86.6038647 L93.2898567,134.333333 L110.63768,134.333333 L110.63768,86.6038647 C116.603863,86.879227 123.487923,91.1014493 123.487923,99.9130433 L123.487923,134.333333 L137.806763,134.333333 L137.806763,99.9130433 C137.806763,91.1014493 144.69082,86.879227 150.657003,86.6038647 L150.657003,134.333333 L166.26087,134.333333 L166.26087,71 L150.657003,71 C142.120773,71 133.859903,75.589372 130.647343,80.178744 C127.434783,75.589372 119.173913,71 110.63768,71 L93.2898567,71 C84.7536233,71 76.4927533,75.589372 73.2801933,80.178744 C70.0676333,75.589372 61.8067633,71 53.27053,71 Z" stroke="#979797"></path></svg>

Example code