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利用threejs实现一个简易的泊车功能

作者：_lucas

这篇文章主要为大家详细介绍了如何利用threejs实现一个简易的泊车功能,文中的示例代码讲解详细,对大家的学习和工作有一定的帮助,感兴趣的小伙伴可以动手尝试一下

简易版小车

因为之前用的模型比较大，加载很慢，这里就先自己简单实现一辆小车（后面统称自车），如下图：

将车轮、车体和边框组合成一个 Group，便于后面做自车的一些操作，实现代码如下：

 // 自车车体
const geometry = new THREE.BoxGeometry(2, 0.6, 3);
const material = new THREE.MeshBasicMaterial({
  color: 0x00ffff,
  side: THREE.DoubleSide,
});
const vehicle = new THREE.Mesh(geometry, material);
vehicle.position.set(0, 1, 0);
scene.add(vehicle);
// 增加自车边框
const box = geometry.clone();
const edges = new THREE.EdgesGeometry(box);
const edgesMaterial = new THREE.LineBasicMaterial({
  color: 0x333333,
});
const line = new THREE.LineSegments(edges, edgesMaterial);
line.position.x = 0;
line.position.y = 1;
line.position.z = 0;
scene.add(line);
// 组成一个Group
const egoCar = new THREE.Group();
egoCar.name = "自车";
egoCar.add(vehicle, line);
scene.add(egoCar);
// 车轮
const axlewidth = 0.7;
const radius = 0.4;
const wheels: any[] = [];
const wheelObjects: any[] = [];
wheels.push({ position: [axlewidth, 0.4, -1], radius });
wheels.push({
  position: [-axlewidth, 0.4, -1],
  radius,
});
wheels.push({ position: [axlewidth, 0.4, 1], radius });
wheels.push({ position: [-axlewidth, 0.4, 1], radius });
wheels.forEach(function (wheel) {
  const geometry = new THREE.CylinderGeometry(
    wheel.radius,
    wheel.radius,
    0.4,
    32
  );
  const material = new THREE.MeshPhongMaterial({
    color: 0xd0901d,
    emissive: 0xee0000,
    side: THREE.DoubleSide,
    flatShading: true,
  });
  const cylinder = new THREE.Mesh(geometry, material);
  cylinder.geometry.rotateZ(Math.PI / 2);
  cylinder.position.set(
    wheel.position[0],
    wheel.position[1],
    wheel.position[2]
  );
  egoCar.add(cylinder);
  // 后面修改车轮方向会用到
  wheelObjects.push(cylinder);
});

跟车相机

让相机一直跟着自车，体验更好一点

// ...
const camera = new THREE.PerspectiveCamera(45, width / height, 0.1, 800);
// 设置摄像机位置，并将其朝向场景中心
camera.position.x = 0;
// camera.position.y = 10;
// camera.position.z = 20;
// camera.lookAt(scene.position);
camera.lookAt(egoCar.position);
// ...
function animate() {
  stats.begin();
  controls.update();
  // 相机跟随自车
  camera.position.y = egoCar.position.y + 15;
  camera.position.z = egoCar.position.z + 25;
  camera.lookAt(egoCar.position);
  renderer.render(scene, camera);
  stats.end();
  requestAnimationFrame(animate);
}
// ...

自车行驶

实现自车前行后退和左右转向

// ...
// 记录开始按下的时间
let startTime = 0;
const activeKeys = new Set();
let t = 0;
document.addEventListener("keydown", (e) => {
  activeKeys.add(e.key);
  if (startTime === 0) {
    startTime = Date.now();
  }
  t = (Date.now() - startTime) / 1000;
  if (t > 10) {
    t = 10;
  }
});
document.addEventListener("keyup", (e) => {
  activeKeys.delete(e.key);
  if (activeKeys.size === 0) {
    startTime = 0;
  }
});
function animate() {
  stats.begin();
  controls.update();
  // 相机跟随自车
  camera.position.y = egoCar.position.y + 15;
  camera.position.z = egoCar.position.z + 25;
  camera.lookAt(egoCar.position);
  if (activeKeys.has("ArrowUp")) {
    // 估算对应方向的移动距离
    egoCar.position.z -= t * 0.1 * Math.cos(egoCar.rotation.y);
    egoCar.position.x -= t * 0.1 * Math.sin(egoCar.rotation.y);
  }
  if (activeKeys.has("ArrowDown")) {
    egoCar.position.z += t * 0.1 * Math.cos(egoCar.rotation.y);
    egoCar.position.x += t * 0.1 * Math.sin(egoCar.rotation.y);
  }
  if (activeKeys.has("ArrowLeft")) {
    egoCar.rotation.y += 0.01;
  }
  if (activeKeys.has("ArrowRight")) {
    egoCar.rotation.y -= 0.01;
  }
  renderer.render(scene, camera);
  stats.end();
  requestAnimationFrame(animate);
}
//...

车轮转动

遍历车轮对象，动态修改车轮的偏转角 rotation，以车头方向为基准偏转固定的角度

function animate() {
  // ...
  if (activeKeys.has("ArrowLeft")) {
    egoCar.rotation.y += 0.01;
    wheelObjects.forEach((wheel) => {
      wheel.rotation.y = egoCar.rotation.y + Math.PI / 4;
    });
  }
  if (activeKeys.has("ArrowRight")) {
    egoCar.rotation.y -= 0.01;
    wheelObjects.forEach((wheel) => {
      wheel.rotation.y = egoCar.rotation.y - Math.PI / 4;
    });
  }
  // ...
}

行进效果还是有点僵硬(能用就行)，这里的问题是行进方向应该是按车头方向，而不是固定按某个坐标轴方向，不过这里也只是简单模拟这个行进效果，后面再引入物理库 cannon.js优化下这块控制逻辑

泊车功能

车位实现

做一个贴地面的矩形框来模拟车位，可以使用 THREE.PlaneGeometry 来创建平面几何体

createParkingSpace() {
    const plane = new THREE.PlaneGeometry(8, 5);
    const material = new THREE.MeshPhongMaterial({
      color: 0x666666,
      side: THREE.DoubleSide,
    });
    const mesh = new THREE.Mesh(plane, material);
    mesh.rotation.x = -Math.PI / 2;
    mesh.position.set(10, 0.12, -20);
    this.scene?.add(mesh);
    // 增加自定义type，便于后面处理车位的选中逻辑
    mesh.userData.type = "parkingSpace";
}

现在咱们把小车开过去停到那个位置

自动泊车

需要实现点击车位后高亮对应的车位，之后小车自动行驶到对应的位置并停好。点击原理是用射线的方式采集第一个碰到的车位物体，当点击鼠标时，会发生以下步骤：

function handleParkSpaceClick(event: any) {
  let vector = new THREE.Vector3(
    (event.clientX / window.innerWidth) * 2 - 1,
    -(event.clientY / window.innerHeight) * 2 + 1,
    0.5
  );
  vector = vector.unproject(camera);
  const raycaster = new THREE.Raycaster(
    camera.position,
    vector.sub(camera.position).normalize()
  );
  const intersects = raycaster.intersectObjects(scene.children);
  for (let i = 0; i < intersects.length; i++) {
    const obj = intersects[i];
    // @ts-ignore
    if (obj.object.userData.type === "parkingSpace")
      // @ts-ignore
      obj.object.material.color.set(0x00ff00);
  }
}
document.addEventListener("click", handleParkSpaceClick);

自动泊车的实现逻辑也比较简单，这里简单记住了车位的位置信息，然后让小车按一定的偏移驶入，其实实际场景可能还要考虑躲避障碍物、加减速、偏转角等，一般也不由前端操心这些。实现代码参考 three-gta v0.1.1 -- 在线体验

到此这篇关于利用threejs实现一个简易的泊车功能的文章就介绍到这了,更多相关threejs泊车功能内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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