从 Box3 创建 BoxBufferGeometry

Question

我想在 Three.js 场景上创建一个盒网格，其中盒网格的点将与场景中某些现有对象的边界框相同。

我尝试按照下面显示的方式从 box3 创建盒网格，但我没有得到正确的结果：

var threeObject = existing object on the scene;
var boundingBox = new THREE.Box3();
boundingBox.setFromObject(threeObject);

var geometry = new THREE.BufferGeometry();
var vertices = new Float32Array( [
boundingBox.min.x, boundingBox.min.y, boundingBox.min.z,  
boundingBox.min.x, boundingBox.max.y, boundingBox.min.z, 
boundingBox.min.x, boundingBox.min.y, boundingBox.max.z, 
boundingBox.min.x, boundingBox.max.y, boundingBox.max.z, 
boundingBox.max.x, boundingBox.min.y, boundingBox.min.z,  
boundingBox.max.x, boundingBox.max.y, boundingBox.min.z, 
boundingBox.max.x, boundingBox.min.y, boundingBox.max.z, 
boundingBox.max.x, boundingBox.max.y, boundingBox.max.z,
] );
geometry.addAttribute( 'position', new THREE.BufferAttribute( vertices, 3 ) );
var material = new THREE.MeshBasicMaterial( { color: 0xff0000 } );
var mesh = new THREE.Mesh( geometry, material );
viewer.scene.add(mesh);

如何从 box3 创建网格盒？非常感谢您的帮助！

Answer 1

在 Three.js 中，没有自动方法将 Box3 转换为常规 BoxBufferGeometry，但它对我来说是如何工作的

const threeObject = existing object on the scene;
const box3 = new THREE.Box3();

// conform to the object size like it's a boundingBox
box3.setFromObject(threeObject);

// make a BoxGeometry of the same size as Box3
const dimensions = new THREE.Vector3().subVectors( box3.max, box3.min );
const boxGeo = new THREE.BoxGeometry(dimensions.x, dimensions.y, dimensions.z);

// move new mesh center so it's aligned with the original object
const matrix = new THREE.Matrix4().setPosition(dimensions.addVectors(box3.min, box3.max).multiplyScalar( 0.5 ));
boxGeo.applyMatrix4(matrix);

// make a mesh
const mesh = new THREE.Mesh(boxGeo, new THREE.MeshBasicMaterial( { color: 0xffcc55 } ));