87 Three.js 手动创建SkinnedMesh的骨骼和绑定动画
简介
这一节，为了提高自己对SkinnedMesh的理解，查看了官方文档里面的对于这一个功能的介绍。发现，官方竟然是通过手动创建了一个模型。并独自绑定了相关的骨骼，我们可以通过dat.gui插件调整骨骼的缩放，位置和转向来查看骨骼的移动对模型造成的相关影响。
案例实现
案例查看地址：http://www.wjceo.com/blog/threejs/2018-04-22/150.html
为了实现以上案例，我们需要先创建相关的几何体，案例中，我们创建了一个圆柱体的几何体，并且可以通过设置可以设置长度和节数，并设置每一个顶点受到骨骼下标的影响及权重：
var geometry = new THREE.CylinderGeometry(
5, // 顶部圆柱体的半径
5, // 底部圆柱体的半径
sizing.height, // 圆柱体的高度
8, // 圆柱周围的分段面数
sizing.segmentCount * 3, // 沿圆柱体高度的面的行数
true // 圆柱体的末端是打开
);
//遍历几何体所有的顶点
for ( var i = 0; i < geometry.vertices.length; i ++ ) {
//根据顶点的位置计算出骨骼影响下标和权重
var vertex = geometry.vertices[ i ];
var y = ( vertex.y + sizing.halfHeight );
var skinIndex = Math.floor( y / sizing.segmentHeight );
var skinWeight = ( y % sizing.segmentHeight ) / sizing.segmentHeight;
geometry.skinIndices.push( new THREE.Vector4( skinIndex, skinIndex + 1, 0, 0 ) );
geometry.skinWeights.push( new THREE.Vector4( 1 - skinWeight, skinWeight, 0, 0 ) );
}
return geometry;然后：我们通过实例化new THREE.Bone()创建了一组骨骼，并且设置好相关的父子级别关系：
var prevBone = new THREE.Bone();
bones.push( prevBone );
prevBone.position.y = - sizing.halfHeight;
for ( var i = 0; i < sizing.segmentCount; i ++ ) {
var bone = new THREE.Bone();
bone.position.y = sizing.segmentHeight;
bones.push( bone ); //添加到骨骼数组
prevBone.add( bone ); //上一个骨骼定义为父级
prevBone = bone;
}最后，我们通过整合，使用geometry创建THREE.SkinnedMesh模型，然后通过那一组骨骼创建THREE.Skeleton骨架，并将骨骼添加到模型里面，模型绑定骨架：
mesh = new THREE.SkinnedMesh( geometry, [material, lineMaterial] );
var skeleton = new THREE.Skeleton( bones ); //创建骨架
mesh.add( bones[ 0 ] ); //将骨骼添加到模型里面
mesh.bind( skeleton ); //模型绑定骨架为了能清晰的看清楚骨骼，我们这节也添加了相关的辅助：
//添加骨骼辅助标记
skeletonHelper = new THREE.SkeletonHelper( mesh );
skeletonHelper.material.linewidth = 2;
scene.add( skeletonHelper );案例代码
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Titletitle>
<style type="text/css">
html, body {
margin: 0;
height: 100%;
}
canvas {
display: block;
}
style>
head>
<body onload="draw();">
body>
<script src="https://cdn.bootcss.com/three.js/91/three.min.js">script>
<script src="/lib/js/controls/OrbitControls.js">script>
<script src="https://cdn.bootcss.com/stats.js/r17/Stats.min.js">script>
<script src="https://cdn.bootcss.com/dat-gui/0.7.1/dat.gui.min.js">script>
<script src="/lib/js/Detector.js">script>
<script>
var renderer, camera, scene, gui, light, stats, controls, mesh, skeletonHelper, bones;
var state = {
animateBones : false
};
function initRender() {
renderer = new THREE.WebGLRenderer({antialias: true});
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.setClearColor(0xeeeeee);
//告诉渲染器需要阴影效果
document.body.appendChild(renderer.domElement);
}
function initCamera() {
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
camera.position.set(0, 40, 50);
}
function initScene() {
scene = new THREE.Scene();
}
//初始化dat.GUI简化试验流程
function initGui() {
gui = new dat.GUI();
var folder = gui.addFolder( "General Options" );
folder.add( state, "animateBones" );
folder.__controllers[ 0 ].name( "Animate Bones" );
folder.add( mesh, "pose" );
folder.__controllers[ 1 ].name( ".pose()" );
var bones = mesh.skeleton.bones;
for ( var i = 0; i < bones.length; i ++ ) {
var bone = bones[ i ];
folder = gui.addFolder( "Bone " + i );
folder.add( bone.position, 'x', - 10 + bone.position.x, 10 + bone.position.x );
folder.add( bone.position, 'y', - 10 + bone.position.y, 10 + bone.position.y );
folder.add( bone.position, 'z', - 10 + bone.position.z, 10 + bone.position.z );
folder.add( bone.rotation, 'x', - Math.PI * 0.5, Math.PI * 0.5 );
folder.add( bone.rotation, 'y', - Math.PI * 0.5, Math.PI * 0.5 );
folder.add( bone.rotation, 'z', - Math.PI * 0.5, Math.PI * 0.5 );
folder.add( bone.scale, 'x', 0, 2 );
folder.add( bone.scale, 'y', 0, 2 );
folder.add( bone.scale, 'z', 0, 2 );
folder.__controllers[ 0 ].name( "position.x" );
folder.__controllers[ 1 ].name( "position.y" );
folder.__controllers[ 2 ].name( "position.z" );
folder.__controllers[ 3 ].name( "rotation.x" );
folder.__controllers[ 4 ].name( "rotation.y" );
folder.__controllers[ 5 ].name( "rotation.z" );
folder.__controllers[ 6 ].name( "scale.x" );
folder.__controllers[ 7 ].name( "scale.y" );
folder.__controllers[ 8 ].name( "scale.z" );
}
}
function initLight() {
scene.add(new THREE.AmbientLight(0x444444));
light = new THREE.PointLight(0xffffff);
light.position.set(0, 50, 0);
//告诉平行光需要开启阴影投射
light.castShadow = true;
scene.add(light);
}
function initModel() {
//辅助工具
var helper = new THREE.AxesHelper(50);
scene.add(helper);
//制作模型
var segmentHeight = 6; //每一节骨骼的的高度
var segmentCount = 4; //总节数
var height = segmentHeight * segmentCount; //总高度
var halfHeight = height * 0.5; //总高度一半的高度
var sizing = {
segmentHeight : segmentHeight,
segmentCount : segmentCount,
height : height,
halfHeight : halfHeight
};
var geometry = createGeometry( sizing ); //创建几何体
var bones = createBones( sizing ); //创建骨骼
mesh = createMesh( geometry, bones ); //创建网格模型
//mesh.scale.multiplyScalar( 1 );
scene.add( mesh );
}
//创建集合体
function createGeometry ( sizing ) {
var geometry = new THREE.CylinderGeometry(
5, // 顶部圆柱体的半径
5, // 底部圆柱体的半径
sizing.height, // 圆柱体的高度
8, // 圆柱周围的分段面数
sizing.segmentCount * 3, // 沿圆柱体高度的面的行数
true // 圆柱体的末端是打开
);
//添加绘制第二个纹理的面
var len = geometry.faces.length;
for(var i=0; i < len; i++){
var face = geometry.faces[i].clone();
face.materialIndex = 1;
geometry.faces.push(face);
}
//将vertexUv报错解决掉
var len = geometry.faceVertexUvs[0].length;
for(var i=0; i < len; i++){
geometry.faceVertexUvs[0].push(geometry.faceVertexUvs[0][i]);
}
//遍历几何体所有的顶点
for ( var i = 0; i < geometry.vertices.length; i ++ ) {
//根据顶点的位置计算出骨骼影响下标和权重
var vertex = geometry.vertices[ i ];
var y = ( vertex.y + sizing.halfHeight );
var skinIndex = Math.floor( y / sizing.segmentHeight );
var skinWeight = ( y % sizing.segmentHeight ) / sizing.segmentHeight;
geometry.skinIndices.push( new THREE.Vector4( skinIndex, skinIndex + 1, 0, 0 ) );
geometry.skinWeights.push( new THREE.Vector4( 1 - skinWeight, skinWeight, 0, 0 ) );
}
return geometry;
}
//创建骨骼
function createBones ( sizing ) {
bones = [];
var prevBone = new THREE.Bone();
bones.push( prevBone );
prevBone.position.y = - sizing.halfHeight;
for ( var i = 0; i < sizing.segmentCount; i ++ ) {
var bone = new THREE.Bone();
bone.position.y = sizing.segmentHeight;
bones.push( bone ); //添加到骨骼数组
prevBone.add( bone ); //上一个骨骼定义为父级
prevBone = bone;
}
return bones;
}
function createMesh ( geometry, bones ) {
var material = new THREE.MeshPhongMaterial( {
skinning : true,
color: 0x156289,
emissive: 0x072534,
side: THREE.DoubleSide,
flatShading: true
} );
var lineMaterial = new THREE.MeshBasicMaterial({
skinning : true,
wireframe: true
});
mesh = new THREE.SkinnedMesh( geometry, [material, lineMaterial] );
var skeleton = new THREE.Skeleton( bones ); //创建骨架
mesh.add( bones[ 0 ] ); //将骨骼添加到模型里面
mesh.bind( skeleton ); //模型绑定骨架
//添加骨骼辅助标记
skeletonHelper = new THREE.SkeletonHelper( mesh );
skeletonHelper.material.linewidth = 2;
scene.add( skeletonHelper );
return mesh;
}
//初始化性能插件
function initStats() {
stats = new Stats();
document.body.appendChild(stats.dom);
}
function initControls() {
controls = new THREE.OrbitControls(camera, renderer.domElement);
// 如果使用animate方法时，将此函数删除
//controls.addEventListener( 'change', render );
// 使动画循环使用时阻尼或自转 意思是否有惯性
controls.enableDamping = true;
//动态阻尼系数 就是鼠标拖拽旋转灵敏度
//controls.dampingFactor = 0.25;
//是否可以缩放
controls.enableZoom = true;
//是否自动旋转
controls.autoRotate = false;
controls.autoRotateSpeed = 0.5;
//设置相机距离原点的最远距离
controls.minDistance = 1;
//设置相机距离原点的最远距离
controls.maxDistance = 2000;
//是否开启右键拖拽
controls.enablePan = true;
}
function render() {
var time = Date.now() * 0.001;
//Wiggle the bones
if ( state.animateBones ) {
for ( var i = 0; i < mesh.skeleton.bones.length; i ++ ) {
mesh.skeleton.bones[ i ].rotation.z = Math.sin( time ) * 2 / mesh.skeleton.bones.length;
}
}
controls.update();
}
//窗口变动触发的函数
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize(window.innerWidth, window.innerHeight);
}
function animate() {
//更新控制器
render();
//更新性能插件
stats.update();
renderer.render(scene, camera);
requestAnimationFrame(animate);
}
function draw() {
//兼容性判断
if (!Detector.webgl) Detector.addGetWebGLMessage();
initStats();
initRender();
initScene();
initCamera();
initLight();
initModel();
initControls();
initGui();
animate();
window.onresize = onWindowResize;
}
script>
html>