实现思路
- 首先是需要用canvas绘制一个2D的热力图，如果你还不会，请看json绘制热力图。
- 使用Threejs中的canvas贴图，将贴图贴在PlaneGeometry平面上。
- 使用着色器材质，更具json中的数据让平面模型 拔地而起。
- 使用Threejs内置的TWEEN，加上一个动画。
效果
效果如下：
具体代码
具体实现效果代码：
import * as THREE from 'three';
import * as TWEEN from 'three/examples/jsm/libs/tween.module.js';
import { OrbitControls } from 'three/addons/controls/OrbitControls.js'
import * as d3geo from 'd3-geo'
import trafficJSON from '../assets/json/traffic.json'export default (domId) => {/* ------------------------------初始化三件套--------------------------------- */const dom = document.getElementById(domId);const { innerHeight, innerWidth } = windowconst scene = new THREE.Scene();const camera = new THREE.PerspectiveCamera(45, innerWidth / innerHeight, 1, 2000);camera.position.set(-25, 288, 342);camera.lookAt(scene.position);const renderer = new THREE.WebGLRenderer({antialias: true,// 抗锯齿alpha: false,// 透明度powerPreference: 'high-performance',// 性能logarithmicDepthBuffer: true,// 深度缓冲})// renderer.setClearColor(0x000000, 0);// 设置背景色// renderer.clear();// 清除渲染器renderer.shadowMap.enabled = true;// 开启阴影renderer.shadowMap.type = THREE.PCFSoftShadowMap;// 阴影类型renderer.outputEncoding = THREE.sRGBEncoding;// 输出编码renderer.toneMapping = THREE.ACESFilmicToneMapping;// 色调映射renderer.toneMappingExposure = 1;// 色调映射曝光renderer.physicallyCorrectLights = true;// 物理正确灯光renderer.setPixelRatio(devicePixelRatio);// 设置像素比renderer.setSize(innerWidth, innerHeight);// 设置渲染器大小dom.appendChild(renderer.domElement);// 重置大小window.addEventListener('resize', () => {const { innerHeight, innerWidth } = windowcamera.aspect = innerWidth / innerHeight;camera.updateProjectionMatrix();renderer.setSize(innerWidth, innerHeight);})/* ------------------------------初始化工具--------------------------------- */const controls = new OrbitControls(camera, renderer.domElement) // 相机轨道控制器controls.enableDamping = true // 是否开启阻尼controls.dampingFactor = 0.05// 阻尼系数controls.panSpeed = -1// 平移速度const axesHelper = new THREE.AxesHelper(10);scene.add(axesHelper);/* ------------------------------正题--------------------------------- */let geoFun;// 地理投影函数let info = {max: Number.MIN_SAFE_INTEGER,min: Number.MAX_SAFE_INTEGER,maxlng: Number.MIN_SAFE_INTEGER,minlng: Number.MAX_SAFE_INTEGER,maxlat: Number.MIN_SAFE_INTEGER,minlat: Number.MAX_SAFE_INTEGER,data: []};// 初始化地理投影const initGeo = (size) => {geoFun = d3geo.geoMercator().scale(size || 100)}// 经纬度转像素坐标const latlng2px = (pos) => {if (pos[0] >= -180 && pos[0] <= 180 && pos[1] >= -90 && pos[1] <= 90) {return geoFun(pos);}return pos;};// 创建颜色const createColors = (option) => {const canvas = document.createElement('canvas');const ctx = canvas.getContext('2d');canvas.width = 256;canvas.height = 1;const grad = ctx.createLinearGradient(0, 0, canvas.width, canvas.height);for (let k in option.colors) {grad.addColorStop(k, option.colors[k]);}ctx.fillStyle = grad;ctx.fillRect(0, 0, canvas.width, canvas.height);return ctx.getImageData(0, 0, canvas.width, 1).data;}// 绘制圆const drawCircle = (ctx, option, item) => {let { lng, lat, value } = item;let x = lng - option.minlng + option.radius;let y = lat - option.minlat + option.radius;const grad = ctx.createRadialGradient(x, y, 0, x, y, option.radius);grad.addColorStop(0.0, 'rgba(0,0,0,1)');grad.addColorStop(1.0, 'rgba(0,0,0,0)');ctx.fillStyle = grad;ctx.beginPath();ctx.arc(x, y, option.radius, 0, 2 * Math.PI);ctx.closePath();ctx.globalAlpha = (value - option.min) / option.size;ctx.fill();}// 创建热力图const createHeatmap = (option) => {const canvas = document.createElement('canvas');canvas.width = option.width;canvas.height = option.height;const ctx = canvas.getContext('2d');option.size = option.max - option.min;option.data.forEach((item) => {drawCircle(ctx, option, item);});const colorData = createColors(option);const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);for (let i = 3; i < imageData.data.length; i = i + 4) {let opacity = imageData.data[i];let offset = opacity * 4;//redimageData.data[i - 3] = colorData[offset];//greenimageData.data[i - 2] = colorData[offset + 1];//blueimageData.data[i - 1] = colorData[offset + 2];}ctx.putImageData(imageData, 0, 0);return { canvas, option };}// 初始化const init = () => {initGeo(1000)// 处理数据trafficJSON.features.forEach((item) => {let pos = latlng2px(item.geometry.coordinates);// 经纬度转像素坐标let newitem = {lng: pos[0],lat: pos[1],value: item.properties.avg}info.max = Math.max(newitem.value, info.max);info.maxlng = Math.max(newitem.lng, info.maxlng);info.maxlat = Math.max(newitem.lat, info.maxlat);info.min = Math.min(newitem.value, info.min);info.minlng = Math.min(newitem.lng, info.minlng);info.minlat = Math.min(newitem.lat, info.minlat);info.data.push(newitem);})info.size = info.max - info.min;info.sizelng = info.maxlng - info.minlng;info.sizelat = info.maxlat - info.minlat;const radius = 50;const { canvas, option } = createHeatmap({width: info.sizelng + radius * 2,height: info.sizelng + radius * 2,colors: {0.1: '#2A85B8',0.2: '#16B0A9',0.3: '#29CF6F',0.4: '#5CE182',0.5: '#7DF675',0.6: '#FFF100',0.7: '#FAA53F',1: '#D04343'},radius,...info})const map = new THREE.CanvasTexture(canvas);map.wrapS = THREE.RepeatWrapping;map.wrapT = THREE.RepeatWrapping;// 创建平面const geometry = new THREE.PlaneGeometry(option.width * 0.5,option.height * 0.5,500,500);const material = new THREE.ShaderMaterial({transparent: true,side: THREE.DoubleSide,uniforms: {map: { value: map },uHeight: { value: 100 },uOpacity: { value: 2.0 }},vertexShader: `uniform sampler2D map;uniform float uHeight;varying vec2 v_texcoord;void main(void){v_texcoord = uv;float h=texture2D(map, v_texcoord).a*uHeight;gl_Position = projectionMatrix * modelViewMatrix * vec4( position.x,position.y,h, 1.0 );}`,fragmentShader: `precision mediump float;uniform sampler2D map;uniform float uOpacity;varying vec2 v_texcoord;void main (void){vec4 color= texture2D(map, v_texcoord);float a=color.a*uOpacity;gl_FragColor.rgb =color.rgb;gl_FragColor.a=a>1.0?1.0:a;}`});const plane = new THREE.Mesh(geometry, material);plane.rotateX(-Math.PI * 0.5);scene.add(plane);const tween = new TWEEN.Tween({ v: 0 }).to({ v: 100 }, 2000).onUpdate(obj => {material.uniforms.uHeight.value = obj.v;}).easing(TWEEN.Easing.Quadratic.InOut).start();TWEEN.add(tween);}init();/* ------------------------------动画函数--------------------------------- */const animation = () => {TWEEN.update();controls.update();// 如果不调用，就会很卡renderer.render(scene, camera);requestAnimationFrame(animation);}animation();
}
