JS仿照3D手办模型展台实现示例详解

2024-04-02 19:04:59 909人浏览安东尼

摘要

目录前言效果预览代码片段styleScript核心科技获取旋转角度监听 touch 事件，通过开始、结束坐标计算移动方向根据坐标计算移动方向PC端支持 touch 事件前言前几年实

前言

前几年实现的一个 demo 效果，今天翻出来整理下，给大家提供类似场景参考思路。

当时的需求场景是需要 3D 展示手办模型，但是因为甲方预算有限，问有没有其他青春版（性价比）方案。

刚好那段时间在处理 lottie 动画跳帧的问题，就提出了给模型拍个全身照，旋转的时候逐帧播放达到模拟手办模型旋转的动画效果。

众所周知，帧率越高，单位时间内图像帧的个数就会越多，对应动画效果就会越流畅，当然了，对应需要准备的模型素材也就越多。

效果预览

代码片段

为了省流，这里没有预渲染图片资源，?可能出现转动太快，图片未加载的情况，请?等待片刻

style

body {
  padding: 24px;
}
.model-box {
  box-shadow: 0 10px 40px #00000029;
  padding: 24px;
  margin: 12px 0;
  border-radius: 12px;
  h4 {
    margin: 12px 0;
  }
  span {
    font-size: 12px;
  }
}
.content-box {
  position: relative;
  width: 318px;
  height: 300px;
  border: 1px solid #2196f3;
  border-radius: 20px;
  margin: 0 auto;
  img {
    position: absolute;
    top: 50%;
    pointer-events: none;
    width: 100%;
    transfORM: translateY(-50%);
  }
}

Script

<template>
  <div class="model-box">
    <button @click="auto">切换为自动旋转</button>
    <h4>模型展台 旋转状态：{{ autoPlay ? '自动' : '手动'}} <span>(左右滑动旋转模型)</span></h4>
    <div class="content-box" ref="content">
      <img
        v-for="(item, i) in modelImgs"
        v-show="i === activeIndex"
        :key="i"
        :src="item"
      />
    </div>
  </div>
</template>
<script>
class ModelBooth {
  constructor ({ el, event, total }) {
    this.$el = el
    this.$event = event
    this.data = {
      total: total,
      index: 0,
      x: 0,
      y: 0
    }
    this.change = this.throttle(this.emitChange.bind(this), 50)
  }
  init () {
    this.addListener()
  }
  addListener () {
    this.$el.addEventListener('touchstart', (e) => {
      this.$event?.onStop()
      this.data.x = e.touches[0].pageX
      this.data.y = e.touches[0].pageY
    }, false)
    this.$el.addEventListener('touchmove', (e) => {
      this.$event?.onStop()
      const endx = e.changedTouches[0].pageX
      const endy = e.changedTouches[0].pageY
      const direction = this.calcDirection(this.data.x, this.data.y, endx, endy)
      switch (direction) {
        case 'left':
          e.preventDefault()
          this.change(false)
          break
        case 'right':
          e.preventDefault()
          this.change(true)
          break
      }
    }, false)
  }
  auto ({ index }) {
    this.data.index = index
    this.change(true)
  }
  throttle (fn, time){
    let t1 = 0
    return function () {
      let t2 = Date.now()
      if (t2 - t1 > time) {
        fn.apply(this, arguments)
        t1 = t2
      }
    }
  }
  emitChange (type) {
    let nowIndex = this.data.index
    if (!type) {
      ++nowIndex
    } else {
      --nowIndex
    }
    const result = ((nowIndex % this.data.total) + this.data.total) % this.data.total
    this.data.index = nowIndex
    this.$event?.onChange(result)
  }
  calcDirection (startX, startY, endX, endY) {
    const angX = endX - startX
    const angY = endY - startY
    let result = ''
    // 消除噪音
    if (Math.abs(angX) < 2 && Math.abs(angY) < 2) {
      return result
    }
    const baseAngle = 45
    const angle = this.calcAngle(angX, angY)
    if (angle >= -(baseAngle * 3) && angle <= -baseAngle) {
      result = 'left'
    } else if (angle > baseAngle && angle < (baseAngle * 3)) {
      result = 'right'
    } else if ((angle >= (baseAngle * 3) && angle <= (baseAngle * 4)) || (angle >= -(baseAngle * 4) && angle < -(baseAngle * 3))) {
      result = 'up'
    } else if (angle >= -baseAngle && angle <= baseAngle) {
      result = 'down'
    }
    return result
  }
  calcAngle (x, y) {
    return Math.atan2(x, y) * 180 / Math.PI
  }
}
export default {
  data() {
    return {
      modelImgs: Array.from({ length: 30 }).map((v, i) => `https://hi-zhang.com/assets/zip/${i}.png`),
      activeIndex: 0,
      autoPlay: false,
      playTn: null
    }
  },
  mounted () {
    this._modelBooth = new ModelBooth({
      el: this.$refs.content,
      total: this.modelImgs.length,
      event: {
        onChange: (index) => {
          this.activeIndex = index
        },
        onStop: () => {
          this.stop()
        }
      }
    })
    this._modelBooth.init()
  },
  methods: {
    stop () {
      this.autoPlay = false
      clearInterval(this.playTn)
    },
    auto () {
      this.stop()
      this.autoPlay = true
      this.playTn = setInterval(() => {
        this._modelBooth.auto({
          index: this.activeIndex
        })
      }, 50)
    }
  }
}
</script>

核心科技

搭建舞台
把抓拍的各个视角模型照片，渲染到舞台上，然后堆叠到一起备用
同时段只展示一个视角的模型照片
旋转时同步视角

相信大家已经知道如何去实现这个需求了，那么就再简单贴一下相关的核心问题处理

获取旋转角度

监听 touch 事件，通过开始、结束坐标计算移动方向

 this.$el.addEventListener('touchstart', (e) => {
  this.data.x = e.touches[0].pageX
  this.data.y = e.touches[0].pageY
}, false)
this.$el.addEventListener('touchmove', (e) => {
  const endx = e.changedTouches[0].pageX
  const endy = e.changedTouches[0].pageY
  const direction = this.calcDirection(this.data.x, this.data.y, endx, endy)
  switch (direction) {
    case 'left':
      e.preventDefault()
      this.change(false)
      break
    case 'right':
      e.preventDefault()
      this.change(true)
      break
  }
}, false)

根据坐标计算移动方向

  calcDirection (startX, startY, endX, endY) {
    const angX = endX - startX
    const angY = endY - startY
    let result = ''
    // 消除噪音
    if (Math.abs(angX) < 2 && Math.abs(angY) < 2) {
      return result
    }
    const baseAngle = 45
    const angle = this.calcAngle(angX, angY)
    if (angle >= -(baseAngle * 3) && angle <= -baseAngle) {
      result = 'left'
    } else if (angle > baseAngle && angle < (baseAngle * 3)) {
      result = 'right'
    } else if ((angle >= (baseAngle * 3) && angle <= (baseAngle * 4)) || (angle >= -(baseAngle * 4) && angle < -(baseAngle * 3))) {
      result = 'up'
    } else if (angle >= -baseAngle && angle <= baseAngle) {
      result = 'down'
    }
    return result
  }
  calcAngle (x, y) {
    return Math.atan2(x, y) * 180 / Math.PI
  }