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Collision Detection using OBB

Description

If you don't need physics simulation, but you still want some kind of collision detection, one option you have is to use an Oriented Bounding Box (OBB).

Lesson Script

./src/client/client.ts

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import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
import Stats from 'three/examples/jsm/libs/stats.module'
import { OBB } from 'three/examples/jsm/math/OBB'

const scene = new THREE.Scene()
scene.add(new THREE.AxesHelper(5))

const light = new THREE.AmbientLight()
scene.add(light)

const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
)
camera.position.set(0.8, 1.4, 3.0)

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

const controls = new OrbitControls(camera, renderer.domElement)
controls.enableDamping = true

const geometry = new THREE.BoxGeometry(1, 2, 3)
geometry.computeBoundingBox()
const material = new THREE.MeshPhongMaterial()
const mesh = new THREE.Mesh(geometry, material)
mesh.position.set(4, 1, 0)
mesh.geometry.userData.obb = new OBB().fromBox3(
    mesh.geometry.boundingBox as THREE.Box3
)
mesh.userData.obb = new OBB()
scene.add(mesh)

const mesh2 = new THREE.Mesh(
    geometry,
    new THREE.MeshBasicMaterial({ color: 0x00ff00, wireframe: true })
)
mesh2.position.set(-3, 1, 0)
mesh2.geometry.userData.obb = new OBB().fromBox3(
    mesh2.geometry.boundingBox as THREE.Box3
)
mesh2.userData.obb = new OBB()

scene.add(mesh2)

const floor = new THREE.Mesh(
    new THREE.PlaneBufferGeometry(20, 20, 10, 10),
    new THREE.MeshBasicMaterial({ color: 0xaec6cf, wireframe: true })
)
floor.rotateX(-Math.PI / 2)
scene.add(floor)

window.addEventListener('resize', onWindowResize, false)
function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight
    camera.updateProjectionMatrix()
    renderer.setSize(window.innerWidth, window.innerHeight)
    render()
}

const stats = Stats()
document.body.appendChild(stats.dom)

const clock = new THREE.Clock()

function animate() {
    requestAnimationFrame(animate)

    mesh.position.x = Math.sin(clock.getElapsedTime() * 0.5) * 4

    controls.update()

    mesh.userData.obb.copy(mesh.geometry.userData.obb)
    mesh2.userData.obb.copy(mesh2.geometry.userData.obb)
    mesh.userData.obb.applyMatrix4(mesh.matrixWorld)
    mesh2.userData.obb.applyMatrix4(mesh2.matrixWorld)
    if (mesh.userData.obb.intersectsOBB(mesh2.userData.obb)) {
        mesh.material.color.set(0xff0000)
    } else {
        mesh.material.color.set(0x00ff00)
    }

    mesh.rotateY(0.01)
    mesh2.rotateY(-0.005)

    render()

    stats.update()
}

function render() {
    renderer.render(scene, camera)
}

animate()

OBB (Official)