// 引入three.js
import * as THREE from 'three'
// 导入轨道控制器
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'

const scence = new THREE.Scene()

const camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.set(0, 0, 10)
camera.lookAt(0, 0, 0)

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth / 2, window.innerHeight / 2)
document.body.appendChild(renderer.domElement)

// ---------------------------------------------------------------------------------------

	const geometry = new THREE.BufferGeometry()
	
	// 创建顶点数据，顶点是有序的，每3个数据确定一个顶点，逆时针为正面
	const vertices = new Float32Array([-1.0, -1.0, 0, 1.0, -1.0, 0, 1.0, 1.0, 0, -1.0, 1.0, 0])
	// 创建顶点属性
	geometry.setAttribute('position', new THREE.BufferAttribute(vertices, 3))
	// 创建索引
	const indices = new Uint16Array([0, 1, 2, 2, 3, 0])
	geometry.setIndex(new THREE.BufferAttribute(indices, 1))
	console.log('使用索引-geometry', geometry)
	
	// 创建顶点组
	// 从`索引indices数组`，下标为0(参数1)的位置开始，包含3(参数2)个顶点，用的是第一个(参数3：0的意思是下标0，即：第一个)材质
	geometry.addGroup(0, 3, 0) 
	// 从`索引indices数组`，下标为3(参数1)的位置开始，包含3(参数2)个顶点，用的是第二个(参数3：1的意思是下标1，即：第二个)材质
	geometry.addGroup(3, 3, 1) 
	
	// 创建材质
	const material = new THREE.MeshBasicMaterial({
	  color: 0x31f609,
	  // wireframe: true
	  // side: THREE.DoubleSide
	})
	const material_1 = new THREE.MeshBasicMaterial({
	  color: 0xe2100f
	})
	
	const plane = new THREE.Mesh(geometry, [material, material_1])
	scence.add(plane)

// ---------------------------------------------------------------------------------------

// 添加世界坐标辅助器，红色-X轴； 绿色-Y轴； 蓝色-Z轴
const axesHelper = new THREE.AxesHelper(5)
scence.add(axesHelper)

const controls = new OrbitControls(camera, renderer.domElement)
// 设置带阻尼的惯性
controls.enableDamping = true
// 设置阻尼系数
controls.dampingFactor = 0.01

// 每一帧根据控制器更新画面
function render() {
  // 如果，需要控制器带有阻尼效果，或者自动旋转等效果，就需要加入`controls.update()`
  controls.update()
  // `requestAnimationFrame`：在屏幕渲染下一帧画面时，触发回调函数来执行画面的渲染
  requestAnimationFrame(render)

  renderer.render(scence, camera)
}
render()

案例2：

// 引入three.js
import * as THREE from 'three'
// 导入轨道控制器
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'

const scence = new THREE.Scene()

const camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.set(0, 0, 10)
camera.lookAt(0, 0, 0)

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth / 2, window.innerHeight / 2)
document.body.appendChild(renderer.domElement)

// -----------------------------------------------------------------

const geometry = new THREE.BoxGeometry(1, 1, 1)

const material_1 = new THREE.MeshBasicMaterial({
  color: 0x31f609
})
const material_2 = new THREE.MeshBasicMaterial({
  color: 0xf63911
})
const material_3 = new THREE.MeshBasicMaterial({
  color: 0xf3f724
})
const material_4 = new THREE.MeshBasicMaterial({
  color: 0x69f3fa
})
const material_5 = new THREE.MeshBasicMaterial({
  color: 0x1b08db
})
const material_6 = new THREE.MeshBasicMaterial({
  color: 0xfa80e9
})

// 6个面，都是不用颜色的立方体
const cube = new THREE.Mesh(geometry, [material_1, material_2, material_3, material_4, material_5, material_6])

scence.add(cube)

// -----------------------------------------------------------------

// 添加世界坐标辅助器，红色-X轴； 绿色-Y轴； 蓝色-Z轴
const axesHelper = new THREE.AxesHelper(5)
scence.add(axesHelper)

const controls = new OrbitControls(camera, renderer.domElement)
// 设置带阻尼的惯性
controls.enableDamping = true
// 设置阻尼系数
controls.dampingFactor = 0.01

// 每一帧根据控制器更新画面
function render() {
  // 如果，需要控制器带有阻尼效果，或者自动旋转等效果，就需要加入`controls.update()`
  controls.update()
  // `requestAnimationFrame`：在屏幕渲染下一帧画面时，触发回调函数来执行画面的渲染
  requestAnimationFrame(render)

  renderer.render(scence, camera)
}
render()