如何在 ThreeJS 中获取边界框的角？

Question

我已经创建了 Object3D 并在其中添加了四个立方体几何体，并计算了 Object3D 的边界框，其中包含四个立方体对象，并使用 BoxHelper 来查看边界框是否正常工作。现在我想要边界框的所有角（即 XYZ，角坐标）。

基本上，我试图实现爆炸和内爆效果，即我的四个立方体从边界框中心的初始位置到达边界框的四个角。

var objectContainer = new THREE.Object3D();
scene.add(objectContainer);
var objectAGeom = new THREE.BoxGeometry(1,1,1);

objectAMesh = new THREE.Mesh(objectAGeom, objectAMaterial);   

scene.add(objectAMesh);
objectContainer.add(objectAMesh);


var objectBGeom = new THREE.BoxGeometry(1,1,1);

var objectBMesh = new THREE.Mesh(objectBGeom, objectBMaterial);


scene.add(objectBMesh);
objectContainer.add(objectBMesh);

var objectCGeom = new THREE.BoxGeometry(1,1,1);

var objectCMesh = new THREE.Mesh(objectCGeom, objectCMaterial);

scene.add(objectCMesh);
objectContainer.add(objectCMesh);

var objectDGeom = new THREE.BoxGeometry(1,1,1);

var objectDMesh = new THREE.Mesh(objectDGeom, objectDMaterial);

scene.add(objectDMesh);
objectContainer.add(objectDMesh);`                            
helper = new   THREE.BoxHelper(objectContainer);
helper.material.color.set(0xbbddff);
scene.add(helper);

boundingBox = new  THREE.Box3();
boundingBox.setFromObject(objectContainer);`

Answer 1

对于初学者，将网格添加到场景中，然后立即将其添加到 Object3D 会使第一个命令无用，因为网格一次只能有一个父对象。

scene.add(objectAMesh); // This does nothing...
objectContainer.add(objectAMesh); // Because you're immediately adding it here

ObjectContainer 已经在场景中，因此您无需通过两种不同的方式将 Meshes 添加到场景中。

其次，您需要使用THREE.Box3 来获取您已经在做的边界框。这会给你the .min and .max values of the BoundingBox。您可以使用它来推断所有 8 个角：

boundingBox = new  THREE.Box3();
boundingBox.setFromObject(objectContainer);

const low = boundingBox.min;
const high = boundingBox.max;

const corner1 = new THREE.Vector3(low.x,    low.y,  low.z);
const corner2 = new THREE.Vector3(high.x,   low.y,  low.z);
const corner3 = new THREE.Vector3(low.x,    high.y, low.z);
const corner4 = new THREE.Vector3(low.x,    low.y,  high.z);

const corner5 = new THREE.Vector3(high.x,   high.y, low.z);
const corner6 = new THREE.Vector3(high.x,   low.y,  high.z);
const corner7 = new THREE.Vector3(low.x,    high.y, high.z);
const corner8 = new THREE.Vector3(high.x,   high.y, high.z);