canvas动画：点随机运动距离内自动连接成线鼠标移动自动吸附附近的点

思路/实现步骤

1. 创建canvas元素
1. 获取canvas的上下文ctx
1. 初始化点的信息（数量、初始坐标、移动方向、移动速度、大小、颜色）
1. 绘制点
1. 绘制点之间的连线
1. 点有规律的动起来
1. 动画循环
1. 鼠标移动相关逻辑
1. 点鼠标之间连线
1. 鼠标吸附逻辑
1. 添加配置项
1. 重绘、重置

示例代码

<template><div class='random-dot-line-canvas'><!-- <div style="margin-bottom: 20px;"><el-button @click="nextDraw">下一帧</el-button></div> --><div class="config"><el-form :inline="true" :model="canvasConfig"><el-form-item label="画布宽度" prop="canvasWidth"><el-input-number v-model="canvasConfig.canvasWidth" :min="800" :max="1920" :step="50"></el-input-number></el-form-item><el-form-item label="画布高度" prop="canvasHeight"><el-input-number v-model="canvasConfig.canvasHeight" :min="200" :max="900" :step="50"></el-input-number></el-form-item><el-form-item label="点数量" prop="DOT_NUM"><el-input-number v-model="canvasConfig.DOT_NUM" :min="10" :max="200" :step="5"></el-input-number></el-form-item><el-form-item label="点半径" prop="DOT_RADIUS"><el-input-number v-model="canvasConfig.DOT_RADIUS" :min="1" :max="20" :step="1"></el-input-number></el-form-item><el-form-item label="点颜色" prop="DOT_COLOR"><el-color-picker v-model="canvasConfig.DOT_COLOR" /></el-form-item><el-form-item label="线颜色" prop="LINE_COLOR"><el-color-picker v-model="canvasConfig.LINE_COLOR" /></el-form-item><el-form-item label="连线最大距离" prop="DOT_DRAW_LINE_MAX_DIST"><el-input-number v-model="canvasConfig.DOT_DRAW_LINE_MAX_DIST" :min="50" :max="400" :step="20"></el-input-number></el-form-item><el-form-item label="点移动速度" prop="DOT_MOVE_SPEED"><el-input-number v-model="canvasConfig.DOT_MOVE_SPEED" :min="1" :max="20" :step="1"></el-input-number></el-form-item><el-form-item><el-button type="primary" @click="redraw">重绘</el-button><el-button type="primary" @click="reset">重置</el-button></el-form-item></el-form></div><canvasv-if="!initing"id="random-dot-line-canvas":width="canvasWidth":height="canvasHeight"style="background-color: black;"color-space="srgb">Your browser does not support the HTML5 canvas tag.</canvas></div>
</template><script setup name='random-dot-line-canvas'>
import { ref, onMounted, nextTick, watch } from 'vue'
import store from '../../../../store';const themeColor = ref(store.state.setting.themeColor || '#ffffff') // 主题色
const ctx = ref()
const initing = ref(true)
const canvasWidth = ref(800) // 画布宽度
const canvasHeight = ref(400) // 画布高度
const dotList = ref([]) // 点的坐标、移动方向/移动速度
const DOT_NUM = ref(40) // 点的数量
const DOT_RADIUS = ref(2.5) // 点的半径
const DOT_COLOR = ref(themeColor) // 点的颜色
const LINE_COLOR = ref(themeColor) // 连线颜色
const DOT_DRAW_LINE_MAX_DIST = ref(100) // 两点之间要连线的最大距离
const DOT_MOVE_SPEED = ref(1) // 点移动速度
const canvasConfig = ref({ // 表单配置项canvasWidth: canvasWidth.value,canvasHeight: canvasHeight.value,DOT_NUM: DOT_NUM.value,DOT_RADIUS: DOT_RADIUS.value,DOT_COLOR: DOT_COLOR.value,LINE_COLOR: LINE_COLOR.value,DOT_DRAW_LINE_MAX_DIST: DOT_DRAW_LINE_MAX_DIST.value,DOT_MOVE_SPEED: DOT_MOVE_SPEED.value,
})
const animationNum = ref(null)
const animationMouseNum = ref(null)
const canvasPositionInPage = ref() // 画布位置
const mousePosition = ref({}) // 鼠标位置onMounted(()=>{init()
})watch(() => mousePosition.value,(newConfig, oldConfig = {}) => {if(newConfig.inCanvas && !oldConfig.inCanvas) {// console.log('移入画布')mouseAdsorb()} else if (newConfig.inCanvas === false) {// console.log('移出画布')cancelAnimationFrame(animationMouseNum.value)}},{ immediate: true, deep: true }
)/** 初始化函数 */
const init = async() => {initing.value = falseawait nextTick()let canvas = document.getElementById('random-dot-line-canvas')canvasPositionInPage.value = canvas.getBoundingClientRect()// {"x": 40, "y": 183, "width": 800, "height": 400, "top": 183, "right": 840, "bottom": 583, "left": 40 }try {ctx.value = canvas.getContext('2d')} catch (error) {console.log('canvas,ctx,getContext', error)}createdDot() // 创建点坐标draw() // 绘制mouseMove() // 鼠标移动相关逻辑dotMove() // 点动起来
}/** 重绘 */
const redraw = () => {cancelAnimationFrame(animationNum.value)initing.value = truesetNewConfigValue(canvasConfig.value)init()
}
/** 重置 */
const reset = () => {initing.value = truesetNewConfigValue({canvasWidth: 800,canvasHeight: 400,DOT_NUM: 40,DOT_RADIUS: 2.5,DOT_DRAW_LINE_MAX_DIST: 100,DOT_MOVE_SPEED: 1,})init()
}/** 设置配置项值 */
const setNewConfigValue = (newConfig) => {canvasWidth.value = newConfig.canvasWidth || canvasWidth.valuecanvasHeight.value = newConfig.canvasHeight || canvasHeight.valueDOT_NUM.value = newConfig.DOT_NUM || DOT_NUM.valueDOT_RADIUS.value = newConfig.DOT_RADIUS || DOT_RADIUS.valueDOT_COLOR.value = newConfig.DOT_COLOR || DOT_COLOR.valueLINE_COLOR.value = newConfig.LINE_COLOR || LINE_COLOR.valueDOT_DRAW_LINE_MAX_DIST.value = newConfig.DOT_DRAW_LINE_MAX_DIST || DOT_DRAW_LINE_MAX_DIST.valueDOT_MOVE_SPEED.value = newConfig.DOT_MOVE_SPEED || DOT_MOVE_SPEED.value
}/** 绘制函数 */
const draw = () => {ctx.value.clearRect(0, 0, canvasWidth.value, canvasHeight.value)drawDot() // 绘制点drawLine() // 连线if(mousePosition.value.inCanvas) { // 鼠标在画布内 执行吸附逻辑drawLineByMouse() // 连线到鼠标}
}/** 下一帧-调试用 */
const nextDraw = () => {dotMove()
}/** 创建点坐标 */
const createdDot =() => {dotList.value = []for (let num = 1; num <= DOT_NUM.value; num++) {const x = getRandomInteger(0, canvasWidth.value)const y = getRandomInteger(0, canvasHeight.value)const move_x = (+(Math.random() * 2 - 1).toFixed(2)) * DOT_MOVE_SPEED.value // 移动x轴的速度const move_y = (+(Math.random() * 2 - 1).toFixed(2)) * DOT_MOVE_SPEED.value // 移动y轴的速度dotList.value.push({x,y,move_x,move_y})}
}/** 绘制点 */
const drawDot = () => {ctx.value.save();ctx.value.translate(0.5, 0.5);dotList.value.forEach((dot, index)=>{ctx.value.fillStyle = index === 0 ? 'red' : DOT_COLOR.value || '#fff'ctx.value.beginPath();ctx.value.arc(dot.x, dot.y, DOT_RADIUS.value, 0, 2*Math.PI)ctx.value.fill()ctx.value.closePath();})ctx.value.restore();
}/** 点之间连线 */
const drawLine = () => {ctx.value.save();ctx.value.translate(0.5, 0.5);const lineColorRgb = hexToRgb(LINE_COLOR.value)dotList.value.forEach((dot1, index1)=>{dotList.value.forEach((dot2, index2)=>{const s = getDistanceByTwoDot(dot1, dot2) // 两点之间的距离if(index1 !== index2 && s <= DOT_DRAW_LINE_MAX_DIST.value) {ctx.value.lineWidth = 1ctx.value.strokeStyle = `rgba(${lineColorRgb.r}, ${lineColorRgb.g}, ${lineColorRgb.b}, ${((DOT_DRAW_LINE_MAX_DIST.value-s) / DOT_DRAW_LINE_MAX_DIST.value)})`ctx.value.beginPath();ctx.value.moveTo(dot1.x, dot1.y)ctx.value.lineTo(dot2.x, dot2.y)ctx.value.stroke()ctx.value.closePath();}})})ctx.value.restore();
}/** 点有规律的动起来 */
const dotMove = () => {dotList.value.forEach((dot, index) => {let nextX = dot.xlet nextY = dot.ynextX = dot.x + dot.move_xnextY = dot.y + dot.move_yif(nextX > canvasWidth.value - DOT_RADIUS.value) {nextX = canvasWidth.value - DOT_RADIUS.valuedot.move_x = -dot.move_x} else if(nextX < DOT_RADIUS.value) {nextX = DOT_RADIUS.valuedot.move_x = -dot.move_x}if(nextY > canvasHeight.value - DOT_RADIUS.value) {nextY = canvasHeight.value - DOT_RADIUS.valuedot.move_y = -dot.move_y} else if(nextY < DOT_RADIUS.value) {nextY = DOT_RADIUS.valuedot.move_y = -dot.move_y}dot.x = nextXdot.y = nextY})draw() // 绘制animationNum.value = requestAnimationFrame(dotMove)
}/** 鼠标移动相关逻辑 */
const mouseMove = () => {const canvas = document.getElementById('random-dot-line-canvas')canvas.addEventListener('mousemove', (e) => {mousePosition.value = {inCanvas: true,x: e.offsetX,y: e.offsetY,offsetX: e.offsetX, // 相对于canvasoffsetY: e.offsetY,pageX: e.pageX, // 相对于页面pageY: e.pageY,}})canvas.addEventListener('mouseleave', (e) => {mousePosition.value.inCanvas = false})
}/** 点移动兼容鼠标位置的戏份逻辑 */
const mouseAdsorb = () => {dotList.value.forEach((dot) => {let nextX = dot.xlet nextY = dot.yconst attractiveRange = DOT_DRAW_LINE_MAX_DIST.value + 50 // 吸引力作用范围const adsorptionDistance = DOT_DRAW_LINE_MAX_DIST.value // 吸附距离const distance = getDistanceByTwoDot(mousePosition.value, dot) // 鼠标和点的距离if(distance < attractiveRange && distance > adsorptionDistance) {dot.isAttractive = true // 点正在被鼠标吸引const { mouse_move_x, mouse_move_y } = getAdsorbSpeed(dot, mousePosition.value) // 计算鼠标吸附点xy方向上的速度nextX += mouse_move_xnextY += mouse_move_y} else if(distance <= adsorptionDistance) { // 吸附点dot.isAdsorption = true // 点已经被吸附dot.isAttractive = false} else {dot.isAttractive = false // 点没有被鼠标吸引dot.isAdsorption = false // 点没有被吸附}dot.x = nextXdot.y = nextY})draw() // 绘制animationMouseNum.value = requestAnimationFrame(mouseAdsorb)
}/** 点鼠标之间连线 */
const drawLineByMouse = () => {ctx.value.save();ctx.value.translate(0.5, 0.5);const lineColorRgb = hexToRgb(LINE_COLOR.value)dotList.value.forEach((dot)=>{if(dot.isAdsorption || dot.isAttractive) { // 被吸引 或 被吸附的点 与鼠标位置连线ctx.value.lineWidth = 1ctx.value.strokeStyle = `rgba(${lineColorRgb.r}, ${lineColorRgb.g}, ${lineColorRgb.b}, ${0.3})`ctx.value.beginPath();ctx.value.moveTo(dot.x, dot.y)ctx.value.lineTo(mousePosition.value.x, mousePosition.value.y)ctx.value.stroke()ctx.value.closePath();}})ctx.value.restore();
}/** 工具函数 */
// 生成min-max范围内随机整数
const getRandomInteger = (min, max) => {return Math.floor(Math.random() * (max - min + 1)) + min;
}
// 计算两点之间的距离
const getDistanceByTwoDot = (dot1, dot2) => {const w = Math.abs(dot1.x - dot2.x)const h = Math.abs(dot1.y - dot2.y)const s = Math.sqrt(w**2 + h**2)return s
}
// 十六进制颜色 转 rgb
function hexToRgb(hex) {if(hex.includes('#')) {hex = hex.replace('#', '')}// 解析红、绿、蓝分量let r = parseInt(hex.substring(0, 2), 16);let g = parseInt(hex.substring(2, 4), 16);let b = parseInt(hex.substring(4, 6), 16) || 0;return { r, g, b };
}
// 计算点被吸引时 x y 方向上的移动速度
const getAdsorbSpeed = (dot, mouse) => {// const distance = getDistanceByTwoDot(dot, mouse) // 鼠标和点的距离const distanceX = mouse.x - dot.xconst distanceY = mouse.y - dot.yconst speed = DOT_MOVE_SPEED.value * 3const mouse_move_x =  +(speed * (distanceX < 0 ? -1 : 1)).toFixed(2)const mouse_move_y =	+(speed * (distanceY < 0 ? -1 : 1) * Math.abs((distanceY / distanceX))).toFixed(2)return { mouse_move_x, mouse_move_y }
}
</script>
<style lang='scss' scoped>
#random-dot-line-canvas {cursor: pointer;
}</style>