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因为之前的几节讲了一些数学方法,例如Vector3、Matrix4、Euler还有Quaternion的知识。所以这篇郭先生就来说说用three.js怎么制作一个魔方。

three.js 如何制作魔方

制作魔方主要运用坐标变换的知识,制作魔方的方法有很多,建议你先在大脑中构思,然后试着做一做,下面我将一种比较简单的方法。

  1. 制作出魔方各个方块的位置坐标(27个)的数组,然后制作出魔方各个面的材质(6个)
  2. 根据坐标和材质制作魔方的方块,并添加到一个组group
  3. 制作一个标志被选面的几何体(我是用球体),然后隐藏
  4. 使用THREE.Raycaster,给模型绑定事件,并记录选定的一些数据,将标志显示并放到合适的位置
  5. 点击模拟方向键盘,根据之前记录的数据,转动魔方(重点)

以上是主要的步骤,但是对于新同学,需要注意的仍然很多,下面上主要代码,按照方法说

1. 定义的变量

posArr = [
  [100,100,100],[100,100,0],[100,100,-100],[100,0,100],[100,0,0],[100,0,-100],[100,-100,100],[100,-100,0],[100,-100,-100],
  [0,100,100],[0,100,0],[0,100,-100],[0,0,100],[0,0,0],[0,0,-100],[0,-100,100],[0,-100,0],[0,-100,-100],
  [-100,100,100],[-100,100,0],[-100,100,-100],[-100,0,100],[-100,0,0],[-100,0,-100],[-100,-100,100],[-100,-100,0],[-100,-100,-100]
],//方块位置坐标
materials,//材质数组
mouse = new THREE.Vector2(),//通过鼠标点击的位置计算出raycaster所需要的点的位置,以屏幕中心为原点,值的范围为-1到1.
raycaster,//射线对象
group,//存放魔方方块的数组
groupTemp,//魔方转动时临时数组
object3d,//魔方被选择面的标志物对象
currentPos,//魔方被点击小块的位置
currentNor,//魔方被点击小块面的法向量
currentUp,//魔方被点击时,相机up的向量

2. 定义材质数组

initMaterial() {
  var map_red = new THREE.TextureLoader().load('/static/images/color/m_red.jpg', () => this.loadover --);
  var map_orange = new THREE.TextureLoader().load('/static/images/color/m_orange.jpg', () => this.loadover --);
  var map_yellow = new THREE.TextureLoader().load('/static/images/color/m_yellow.jpg', () => this.loadover --);
  var map_blue = new THREE.TextureLoader().load('/static/images/color/m_blue.jpg', () => this.loadover --);
  var map_green = new THREE.TextureLoader().load('/static/images/color/m_green.jpg', () => this.loadover --);
  var map_white = new THREE.TextureLoader().load('/static/images/color/m_white.jpg', () => this.loadover --);
  var map_sprite = new THREE.TextureLoader().load('/static/images/base/direction.png', () => this.loadover --);

  let mater_red = new THREE.MeshBasicMaterial({map: map_red, side: THREE.DoubleSide});
  let mater_orange = new THREE.MeshBasicMaterial({map: map_orange, side: THREE.DoubleSide});
  let mater_yellow = new THREE.MeshBasicMaterial({map: map_yellow, side: THREE.DoubleSide});
  let mater_white = new THREE.MeshBasicMaterial({map: map_white, side: THREE.DoubleSide});
  let mater_blue = new THREE.MeshBasicMaterial({map: map_blue, side: THREE.DoubleSide});
  let mater_green = new THREE.MeshBasicMaterial({map: map_green, side: THREE.DoubleSide});

  materials = [mater_red, mater_orange, mater_yellow,mater_white, mater_blue, mater_green];
}

3. 绘制小方块并绘制标志物(先隐藏)

initsquare() {
  var sphereGeom = new THREE.SphereGeometry(10, 30, 20);
  var sphereMate = new THREE.MeshPhongMaterial({color: 0x333333});
  object3d = new THREE.Mesh(sphereGeom, sphereMate);
  object3d.name = 'object3d';
  object3d.visible = false;
  scene.add(object3d);

  group = new THREE.Group();
  group.name = 'group';

  var geometry = new THREE.BoxGeometry(100, 100, 100);
  var mesh = new THREE.Mesh(geometry, materials);
  posArr.forEach((d,i) => {
    let meshCopy = mesh.clone();
    meshCopy.position.set(d[0], d[1], d[2])
    meshCopy.name = 'box-' + i;
    group.add(meshCopy);
  })

  scene.add(group);

  this.render();
  document.getElementById("loading").style.display = "none";
}

4. 监听模型的点击事件

initEventListener() {
  raycaster = new THREE.Raycaster();
  document.addEventListener('mousemove', function (event) {
    event.preventDefault();
    mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
    mouse.y = - (event.clientY / window.innerHeight) * 2 + 1;
  }, false)
  document.addEventListener('mousedown', () => {
    if (scene.children && scene.getObjectByName('group')) {
      raycaster.setFromCamera(mouse, camera);
      let intersects = raycaster.intersectObjects(scene.getObjectByName('group').children);
      if (intersects[0] && intersects[0].object.name != 'object3d') {
        let index = intersects[0].faceIndex;
        let point = intersects[0].point;
        currentUp = this.computedUp(camera);
        currentNor = this.computedNor(point)
        currentPos = intersects[0].object.position;
        let pos = this.computedPos(point);
        object3d.position.copy(pos);
        object3d.visible = true;
      }
    }
  })
}

5. 监听方向软键盘的点击,根据点击键的不同,生成旋转轴

handleRotate(num) {
  if(!rotateFlag || !currentPos) return ;
  rotateFlag = false;
  groupTemp = new THREE.Group();
  groupTemp.name = 'group-temp';
  let axis;
  let tempMeshArr = [];
  switch (num) {
    case 1:
      axis = currentNor.clone().cross(currentUp);
      break;
    case 2:
      axis = currentNor.clone().cross(currentUp).negate();
      break;
    case 3:
      axis = currentUp.clone().negate();
      break;
    case 4:
      axis = currentUp;
      break;
  }
  let plane = new THREE.Plane().setFromNormalAndCoplanarPoint(axis, currentPos);
  scene.getObjectByName('group').children.forEach(d => Math.abs(plane.distanceToPoint(d.position)) < 1 && tempMeshArr.push(d))
  tempMeshArr.forEach(d => {
    group.remove(d);
    groupTemp.add(d);
  })
  // object3d.visible = false;
  scene.remove(scene.getObjectByName('group-temp'));
  scene.add(groupTemp);
  this.handleTween(axis);
}

6. 加一点tween的补间动画,效果更好哦

handleTween(axis) {
  let start = {angle: 0, axis};
  let end = {angle: Math.PI/2, axis};
  tween = new TWEEN.Tween(start).to(end, 500);
  tween.easing(TWEEN.Easing.Linear.None);
  tween.onUpdate(function () {
    let quaternion = new THREE.Quaternion().setFromAxisAngle(axis, this._object.angle);
    groupTemp.rotation.setFromQuaternion(quaternion);
  });
  tween.onComplete(() => {
    let matrix = this.standerMatrix(groupTemp.matrix);
    groupTemp.children.forEach(d => {
      let mesh = d.clone();
      mesh.applyMatrix4(matrix)
      mesh.position.copy(this.standarPos(mesh.position))
      group.add(mesh);
    })
    scene.remove(groupTemp)
    rotateFlag = true;
  })
  tween.start();
}

郭先生制作魔方的主要思路就是先做出27个方块添加到组A,6个面分别添加不同颜色的贴图(自己p的哦),然后使用raycaster选择点击的面,并确定当时的up方向和法向量方向以备后用,点击上下左右并结合u方向和法向量方向计算出旋转矩阵,根据已有条件计算出是那一排方块改变,并将这9个块添加到组B中,从组A中删除这9个,根据旋转矩阵旋转组B,并且在旋转完之后将组B中的方块添加到组A中,旋转完毕(这里比较难的就是根据上下左右判断旋转轴向量)。

以上就是一种制作魔方的方法,综合了很多矩阵向量四元数欧拉角和平面的知识,希望对新来的同游有些帮助

标签:
three.js,魔方,three.js,制作魔方

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