#3 THREEJS 动画

1.render loop中使场景产生动画

可以在循环中使用 requestAnimationFrame 函数，这样如果场景发生变化这会立即生效

// render 循环
function render() {
  requestAnimationFrame(render);
  // 渲染场景
  renderer.render(scene, camera);
}

2.插入动画库

实例：多面体顶点动画

const WIDTH = window.innerWidth;
const HEIGHT = window.innerHeight;

const colors = [0x05A8AA, 0xB8D5B8, 0xD7B49E, 0xDC602E, 
0xBC412B, 0xF19C79, 0xCBDFBD, 0xF6F4D2, 0xD4E09B, 0xFFA8A9, 
0xF786AA, 0xA14A76, 0xBC412B, 0x63A375, 0xD57A66, 0x731A33, 
0xCBD2DC, 0xDBD48E, 0x5E5E5E];

let scene,
    camera,
    renderer,
    geometry,
    mesh;

let verticePositions = [];

// 初始化场景
function initScene() {
  scene = new THREE.Scene();
  camera = new THREE.PerspectiveCamera(30, WIDTH/HEIGHT, 0.1, 1000);
  renderer = new THREE.WebGLRenderer({ alpha: true });
  renderer.setSize(WIDTH, HEIGHT);
  document.body.appendChild(renderer.domElement);
  camera.position.z = 100;
}

// 初始化灯光
function initLight() {
   // 很多光源
  var light = new THREE.DirectionalLight( 0xffffff, 1 );
  light.position.set( 0, 1, 0 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 0.5 );
  light.position.set( 0, -1, 0 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 1 );
  light.position.set( 1, 0, 0 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 0.5 );
  light.position.set( 0, 0, 1 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 1 );
  light.position.set( 0, 0, -1 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 0.5 );
  light.position.set( -1, 0, 0 );
  scene.add( light );
}

// 初始化模型
function initGeometry() {
  // 添加多面体
  // icosahedron 二十面体的意思 当实际表示多面体
  geometry = new THREE.IcosahedronGeometry(20);
  geometry.faces.forEach((face, i) => {
    face.color.setHex(colors[i]);
  });
  mesh = new THREE.Mesh(
    geometry,
    new THREE.MeshBasicMaterial({ vertexColors: THREE.FaceColors })
  );
  scene.add(mesh);
}

function render() {
  requestAnimationFrame(render);
  renderer.render(scene, camera);
}

// 自适应屏幕resize
function resize() {
  camera.aspect = WIDTH/HEIGHT;
  // 更新投射矩阵
  camera.updateProjectionMatrix();
  renderer.setSize(WIDTH, HEIGHT);
}

initScene();
initLight();
initGeometry();
render();

window.addEventListener('resize', resize);

codepen - 在线示例

新的知识点：

  • geometry.faces 属性
  • face.color.setHex(colors[i]) 设置面颜色
  • new THREE.MeshBasicMaterial({ vertexColors: THREE.FaceColors })
  • camera.updateProjectionMatrix() 更新投影矩阵

现在我们有了模型的顶点list,接着我们将随机的改变这些顶点和原始位置的距离。首先我们先将原来多面体的位置存储下来：

function getOriginalVerticePosition() {
  geometry.vertices((vertice, i) => {
    verticePositions.push({
      x: vertice.x,
      y: vertice.y
    });
  })
}

获取模型顶点信息：

  • geometry.vertices[i].x
  • gemotry.vertices[i].y

现在可以改变顶点位置，现在使用 GSAP 动画库：

function getNewVertices() {
  // 这个函数返回一个相对原顶点数据的随机顶点位置的数组
  let newVertices = []
  geometry.vertices.forEach((vertice, i) => {
    newVertices[i] = {
      x: verticePositions[i].x - 5 + Math.random()*10,
      y: verticePositions[i].y - 5 + Math.random()*10,
    }
  });
  return newVertices;
}

function tweenVertice(i, newVerticePositions) {
  // 设置动画
  TweenLite.to(geometry.vertices[i], 1, {
    x: newVerticePositions[i].x,
    y: newVerticePositions[i].y,
    ease: Back.easeInOut,
    onComplete: function() {
      if (i === 0) {
        // 当动画完成时 再次开始动画
        tweenIcosohedron();
      }
    }
  })
}

// 开始多面体动画
function tweenIcosohedron() {
  let newVerticePositions = getNewVertices();
  geometry.vertices.forEach((vertice, i) => {
    tweenVertice(i, newVerticePositions);
  });
}

initScene();
initLight();
initGeometry();
resize();
getOriginalVerticePositions(); // 获取原始模型顶点信息
// console.log('current',verticePositions )
render();
window.addEventListener('resize', resize);

// 开始动画
tweenIcosohedron();

需要注意的是，上面的动画使用了动画库：

完整代码 codepen

另外还可以将模型进行旋转：

function tweenIcosohedron() {
  // 创建一个随机的旋转量
  let rotation = {
    x: Math.random() * 3,
    y: Math.random() * 3,
    z: Math.random() * 3
  };
  TweenLite.to(
    mesh.rotation,
    1,
    {
      x: rotation.x,
      y: rotation.y,
      z: rotation.z,
      ease: Back.easeInOut,
        onComplete: tweenIcosohedron
    },
  );
  let newVerticePositions = getNewVertices();
  geometry.vertices.forEach((vertice, i) => {
    tweenVertice(i, newVerticePositions);
  })
}

完整代码：

const WIDTH = window.innerWidth;
const HEIGHT = window.innerHeight;

const colors = [0x05A8AA, 0xB8D5B8, 0xD7B49E, 0xDC602E, 
0xBC412B, 0xF19C79, 0xCBDFBD, 0xF6F4D2, 0xD4E09B, 0xFFA8A9, 
0xF786AA, 0xA14A76, 0xBC412B, 0x63A375, 0xD57A66, 0x731A33, 
0xCBD2DC, 0xDBD48E, 0x5E5E5E];

let scene,
    camera,
    renderer,
    geometry,
    mesh;

// 用于存储模型顶点信息
let verticePositions = [];

// 初始化场景
function initScene() {
  scene = new THREE.Scene();
  camera = new THREE.PerspectiveCamera(30, WIDTH/HEIGHT, 0.1, 1000);
  renderer = new THREE.WebGLRenderer({ alpha: true });
  renderer.setSize(WIDTH, HEIGHT);
  document.body.appendChild(renderer.domElement);
  camera.position.z = 100;
}

// 初始化灯光
function initLight() {
   // 很多光源
  var light = new THREE.DirectionalLight( 0xffffff, 1 );
  light.position.set( 0, 1, 0 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 0.5 );
  light.position.set( 0, -1, 0 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 1 );
  light.position.set( 1, 0, 0 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 0.5 );
  light.position.set( 0, 0, 1 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 1 );
  light.position.set( 0, 0, -1 );
  scene.add( light );

  var light = new THREE.DirectionalLight( 0xffffff, 0.5 );
  light.position.set( -1, 0, 0 );
  scene.add( light );
}

// 初始化模型
function initGeometry() {
  // 添加多面体
  // icosahedron 二十面体的意思 当实际表示多面体
  geometry = new THREE.IcosahedronGeometry(20);
  geometry.faces.forEach((face, i) => {
    face.color.setHex(colors[i]);
  });
  mesh = new THREE.Mesh(
    geometry,
    new THREE.MeshBasicMaterial({ vertexColors: THREE.FaceColors })
  );
  scene.add(mesh);
}

function render() {
  requestAnimationFrame(render);
  renderer.render(scene, camera);
  geometry.verticesNeedUpdate = true;
}

// 自适应屏幕resize
function resize() {
  camera.aspect = WIDTH/HEIGHT;
  // 更新投射矩阵
  camera.updateProjectionMatrix();
  renderer.setSize(WIDTH, HEIGHT);
}

// 获取模型原来的顶点信息
function getOriginalVerticePositions() {
  geometry.vertices.forEach((vertice, i) => {
    verticePositions.push({
      x: vertice.x,
      y: vertice.y
    });
  })
}

// 创建新的顶点信息
function getNewVertices() {
  // 这个函数返回一个相对原顶点数据的随机顶点位置的数组
  let newVertices = []
  geometry.vertices.forEach((vertice, i) => {
    newVertices[i] = {
      x: verticePositions[i].x - 5 + Math.random()*10,
      y: verticePositions[i].y - 5 + Math.random()*10,
    }
  });
  return newVertices;
}

// function tweenIcosohedron() {
//   let newVerticePositions = getNewVertices();
//   geometry.vertices.forEach((vertice, i) => {
//     tweenVertice(i, newVerticePositions);
//   });
// }
function tweenIcosohedron() {
  // 创建一个随机的旋转量
  let rotation = {
    x: Math.random() * 3,
    y: Math.random() * 3,
    z: Math.random() * 3
  };
  TweenLite.to(
    mesh.rotation,
    1,
    {
      x: rotation.x,
      y: rotation.y,
      z: rotation.z,
      ease: Back.easeInOut,
        onComplete: tweenIcosohedron
    },
  );
  let newVerticePositions = getNewVertices();
  geometry.vertices.forEach((vertice, i) => {
    tweenVertice(i, newVerticePositions);
  })
}

// 开始动画
function tweenVertice(i, newVerticePositions) {
  // 设置动画
  // console.log('hh', geometry.vertices[i])
  TweenLite.to(
    geometry.vertices[i],
    1,
    {
      x: newVerticePositions[i].x,
      y: newVerticePositions[i].y,
      ease: Back.easeInOut,
      onComplete: function() {
        if (i === 0) {
          // 当动画完成时 再次开始动画
          tweenIcosohedron();
        }
      }
    }
  )
}


initScene();
initLight();
initGeometry();
resize();
getOriginalVerticePositions(); // 获取原始模型顶点信息
// console.log('current',verticePositions )
render();
window.addEventListener('resize', resize);

// 开始动画
tweenIcosohedron();

模型旋转 + 顶点变化动画 codepen

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