本文介绍了一个使用THREE.js实现的三维图表动画示例，重点分析了TrackballControls的实现原理及图表动画渲染过程。
因为之后会用到图表插件开发，需要用到THREE.js D3.js ECharts。
D3部分因为已经开发了几个插件部分，个人觉得难点在于数据的预处理与结构的变换，不同于从数据库中的SELECT出的数据部分，可能更多的是需要配合D3.json等接口数据处理的格式，整合数据。
ECharts部分的图表开发，相对于会更加的简练。
THREE.js 感觉不太适用于通用的图表展示，本身是一个实时渲染的过程，个人感觉之后的发展方向会向简单动画部分或者片头去展示，或者是更加高大上的图表，抽象图表部分。
贴代码：
var container, stats;
var camera, controls, scene, renderer;
var effect;
var sphere, plane;
//获取js当前运行的事件
var start = Date.now();
//初始化 属于惯用方法
init();
//动画操作 属于惯用方法
animate();
function init() {
//窗口的大小
var width = window.innerWidth || 2;
var height = window.innerHeight || 2;
//创建div部分 属于惯用方法
container = document.createElement( 'div' );
document.body.appendChild( container );
var info = document.createElement( 'div' );
//样式部分
info.style.position = 'absolute';
info.style.top = '10px';
info.style.width = '100%';
info.style.textAlign = 'center';
info.innerHTML = 'Drag to change the view';
container.appendChild( info );
//镜头部分
camera = new THREE.PerspectiveCamera( 70, width / height, 1, 1000 );
camera.position.y = 150;
camera.position.z = 500;
//控制器部分
controls = new THREE.TrackballControls( camera );
//场景部分
scene = new THREE.Scene();
scene.background = new THREE.Color( 0xf0f0f0 );
//灯光效果,点光源
var light = new THREE.PointLight( 0xffffff );
light.position.set( 500, 500, 500 );
scene.add( light );
//光源颜色，光强度
var light = new THREE.PointLight( 0xffffff, 0.25 );
light.position.set( - 500, - 500, - 500 );
scene.add( light );
//几何 形状 球体 这种材质对光照有反应，用于创建暗淡的不发光的物体
sphere = new THREE.Mesh( new THREE.SphereGeometry( 200, 20, 10 ), new THREE.MeshLambertMaterial() );
scene.add( sphere );
//几何 形状 平面骨架 对光照无感，给几何体一种简单的颜色或显示线框
plane = new THREE.Mesh( new THREE.PlaneBufferGeometry( 400, 400 ), new THREE.MeshBasicMaterial( { color: 0xe0e0e0 } ) );
plane.position.y = - 200;
plane.rotation.x = - Math.PI / 2;
scene.add( plane );
//渲染
renderer = new THREE.CanvasRenderer();
renderer.setSize( width, height );
container.appendChild( renderer.domElement );
effect = new THREE.AsciiEffect( renderer );
effect.setSize( width, height );
container.appendChild( effect.domElement );
stats = new Stats();
container.appendChild( stats.dom );
//添加事件监听
window.addEventListener( 'resize', onWindowResize, false );
}
//页面调整大小，可以理解为鼠标滚轮变化
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
effect.setSize( window.innerWidth, window.innerHeight );
}
//动画部分
function animate() {
//固定格式
requestAnimationFrame( animate );
stats.begin();
render();
stats.end();
}
//渲染操作
function render() {
var timer = Date.now() - start;
sphere.position.y = Math.abs( Math.sin( timer * 0.002 ) ) * 150;
sphere.rotation.x = timer * 0.0003;
sphere.rotation.z = timer * 0.0002;
controls.update();
effect.render( scene, camera );
}采取一步步的分析的过程：
1.针对引用的TrackballControls看一下源码部分
THREE.TrackballControls = function ( object, domElement ) {
var _this = this;
var STATE = { NONE: - 1, ROTATE: 0, ZOOM: 1, PAN: 2, TOUCH_ROTATE: 3, TOUCH_ZOOM_PAN: 4 };
this.object = object;
this.domElement = ( domElement !== undefined ) ? domElement : document;
// API
this.enabled = true;
this.screen = { left: 0, top: 0, width: 0, height: 0 };
//旋转速度
this.rotateSpeed = 1.0;
this.zoomSpeed = 1.2;
this.panSpeed = 0.3;
this.noRotate = false;
this.noZoom = false;
this.noPan = false;
this.staticMoving = false;
this.dynamicDampingFactor = 0.2;
this.minDistance = 0;
this.maxDistance = Infinity;
this.keys = [ 65 /*A*/, 83 /*S*/, 68 /*D*/ ];
// internals
this.target = new THREE.Vector3();
var EPS = 0.000001;
var lastPosition = new THREE.Vector3();
var _state = STATE.NONE,
_prevState = STATE.NONE,
_eye = new THREE.Vector3(),
_movePrev = new THREE.Vector2(),
_moveCurr = new THREE.Vector2(),
_lastAxis = new THREE.Vector3(),
_lastAngle = 0,
_zoomStart = new THREE.Vector2(),
_zoomEnd = new THREE.Vector2(),
_touchZoomDistanceStart = 0,
_touchZoomDistanceEnd = 0,
_panStart = new THREE.Vector2(),
_panEnd = new THREE.Vector2();
// for reset
this.target0 = this.target.clone();
this.position0 = this.object.position.clone();
this.up0 = this.object.up.clone();
// events
var changeEvent = { type: 'change' };
var startEvent = { type: 'start' };
var endEvent = { type: 'end' };
// methods
//处理缩放的问题
this.handleResize = function () {
if ( this.domElement === document ) {
this.screen.left = 0;
this.screen.top = 0;
this.screen.width = window.innerWidth;
this.screen.height = window.innerHeight;
} else {
var box = this.domElement.getBoundingClientRect();
// adjustments come from similar code in the jquery offset() function
var d = this.domElement.ownerDocument.documentElement;
this.screen.left = box.left + window.pageXOffset - d.clientLeft;
this.screen.top = box.top + window.pageYOffset - d.clientTop;
this.screen.width = box.width;
this.screen.height = box.height;
}
};
this.handleEvent = function ( event ) {
if ( typeof this[ event.type ] == 'function' ) {
this[ event.type ]( event );
}
};
//鼠标在屏幕上的处理
var getMouseOnScreen = ( function () {
var vector = new THREE.Vector2();
return function getMouseOnScreen( pageX, pageY ) {
vector.set(
( pageX - _this.screen.left ) / _this.screen.width,
( pageY - _this.screen.top ) / _this.screen.height
);
return vector;
};
}() );
//鼠标按住滑动
var getMouseOnCircle = ( function () {
var vector = new THREE.Vector2();
return function getMouseOnCircle( pageX, pageY ) {
vector.set(
( ( pageX - _this.screen.width * 0.5 - _this.screen.left ) / ( _this.screen.width * 0.5 ) ),
( ( _this.screen.height + 2 * ( _this.screen.top - pageY ) ) / _this.screen.width ) // screen.width intentional
);
return vector;
};
}() );
//镜头滑动
this.rotateCamera = ( function() {
var axis = new THREE.Vector3(),
quaternion = new THREE.Quaternion(),
eyeDirection = new THREE.Vector3(),
objectUpDirection = new THREE.Vector3(),
objectSidewaysDirection = new THREE.Vector3(),
moveDirection = new THREE.Vector3(),
angle;
return function rotateCamera() {
moveDirection.set( _moveCurr.x - _movePrev.x, _moveCurr.y - _movePrev.y, 0 );
angle = moveDirection.length();
if ( angle ) {
_eye.copy( _this.object.position ).sub( _this.target );
eyeDirection.copy( _eye ).normalize();
objectUpDirection.copy( _this.object.up ).normalize();
objectSidewaysDirection.crossVectors( objectUpDirection, eyeDirection ).normalize();
objectUpDirection.setLength( _moveCurr.y - _movePrev.y );
objectSidewaysDirection.setLength( _moveCurr.x - _movePrev.x );
moveDirection.copy( objectUpDirection.add( objectSidewaysDirection ) );
axis.crossVectors( moveDirection, _eye ).normalize();
angle *= _this.rotateSpeed;
quaternion.setFromAxisAngle( axis, angle );
_eye.applyQuaternion( quaternion );
_this.object.up.applyQuaternion( quaternion );
_lastAxis.copy( axis );
_lastAngle = angle;
} else if ( ! _this.staticMoving && _lastAngle ) {
_lastAngle *= Math.sqrt( 1.0 - _this.dynamicDampingFactor );
_eye.copy( _this.object.position ).sub( _this.target );
quaternion.setFromAxisAngle( _lastAxis, _lastAngle );
_eye.applyQuaternion( quaternion );
_this.object.up.applyQuaternion( quaternion );
}
_movePrev.copy( _moveCurr );
};
}() );
//镜头缩放
this.zoomCamera = function () {
var factor;
if ( _state === STATE.TOUCH_ZOOM_PAN ) {
factor = _touchZoomDistanceStart / _touchZoomDistanceEnd;
_touchZoomDistanceStart = _touchZoomDistanceEnd;
_eye.multiplyScalar( factor );
} else {
factor = 1.0 + ( _zoomEnd.y - _zoomStart.y ) * _this.zoomSpeed;
if ( factor !== 1.0 && factor > 0.0 ) {
_eye.multiplyScalar( factor );
}
if ( _this.staticMoving ) {
_zoomStart.copy( _zoomEnd );
} else {
_zoomStart.y += ( _zoomEnd.y - _zoomStart.y ) * this.dynamicDampingFactor;
}
}
};
this.panCamera = ( function() {
var mouseChange = new THREE.Vector2(),
objectUp = new THREE.Vector3(),
pan = new THREE.Vector3();
return function panCamera() {
mouseChange.copy( _panEnd ).sub( _panStart );
if ( mouseChange.lengthSq() ) {
mouseChange.multiplyScalar( _eye.length() * _this.panSpeed );
pan.copy( _eye ).cross( _this.object.up ).setLength( mouseChange.x );
pan.add( objectUp.copy( _this.object.up ).setLength( mouseChange.y ) );
_this.object.position.add( pan );
_this.target.add( pan );
if ( _this.staticMoving ) {
_panStart.copy( _panEnd );
} else {
_panStart.add( mouseChange.subVectors( _panEnd, _panStart ).multiplyScalar( _this.dynamicDampingFactor ) );
}
}
};
}() );
//计算距离
this.checkDistances = function () {
if ( ! _this.noZoom || ! _this.noPan ) {
if ( _eye.lengthSq() > _this.maxDistance * _this.maxDistance ) {
_this.object.position.addVectors( _this.target, _eye.setLength( _this.maxDistance ) );
_zoomStart.copy( _zoomEnd );
}
if ( _eye.lengthSq() < _this.minDistance * _this.minDistance ) {
_this.object.position.addVectors( _this.target, _eye.setLength( _this.minDistance ) );
_zoomStart.copy( _zoomEnd );
}
}
};
//更新页面部分
this.update = function () {
_eye.subVectors( _this.object.position, _this.target );
if ( ! _this.noRotate ) {
_this.rotateCamera();
}
if ( ! _this.noZoom ) {
_this.zoomCamera();
}
if ( ! _this.noPan ) {
_this.panCamera();
}
_this.object.position.addVectors( _this.target, _eye );
_this.checkDistances();
_this.object.lookAt( _this.target );
if ( lastPosition.distanceToSquared( _this.object.position ) > EPS ) {
_this.dispatchEvent( changeEvent );
lastPosition.copy( _this.object.position );
}
};
//重置
this.reset = function () {
_state = STATE.NONE;
_prevState = STATE.NONE;
_this.target.copy( _this.target0 );
_this.object.position.copy( _this.position0 );
_this.object.up.copy( _this.up0 );
_eye.subVectors( _this.object.position, _this.target );
_this.object.lookAt( _this.target );
_this.dispatchEvent( changeEvent );
lastPosition.copy( _this.object.position );
};
// listeners
//事件监听
function keydown( event ) {
if ( _this.enabled === false ) return;
window.removeEventListener( 'keydown', keydown );
_prevState = _state;
if ( _state !== STATE.NONE ) {
return;
} else if ( event.keyCode === _this.keys[ STATE.ROTATE ] && ! _this.noRotate ) {
_state = STATE.ROTATE;
} else if ( event.keyCode === _this.keys[ STATE.ZOOM ] && ! _this.noZoom ) {
_state = STATE.ZOOM;
} else if ( event.keyCode === _this.keys[ STATE.PAN ] && ! _this.noPan ) {
_state = STATE.PAN;
}
}
//事件监听
function keyup( event ) {
if ( _this.enabled === false ) return;
_state = _prevState;
window.addEventListener( 'keydown', keydown, false );
}
//鼠标点击
function mousedown( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
if ( _state === STATE.NONE ) {
_state = event.button;
}
if ( _state === STATE.ROTATE && ! _this.noRotate ) {
_moveCurr.copy( getMouseOnCircle( event.pageX, event.pageY ) );
_movePrev.copy( _moveCurr );
} else if ( _state === STATE.ZOOM && ! _this.noZoom ) {
_zoomStart.copy( getMouseOnScreen( event.pageX, event.pageY ) );
_zoomEnd.copy( _zoomStart );
} else if ( _state === STATE.PAN && ! _this.noPan ) {
_panStart.copy( getMouseOnScreen( event.pageX, event.pageY ) );
_panEnd.copy( _panStart );
}
document.addEventListener( 'mousemove', mousemove, false );
document.addEventListener( 'mouseup', mouseup, false );
_this.dispatchEvent( startEvent );
}
//鼠标移除
function mousemove( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
if ( _state === STATE.ROTATE && ! _this.noRotate ) {
_movePrev.copy( _moveCurr );
_moveCurr.copy( getMouseOnCircle( event.pageX, event.pageY ) );
} else if ( _state === STATE.ZOOM && ! _this.noZoom ) {
_zoomEnd.copy( getMouseOnScreen( event.pageX, event.pageY ) );
} else if ( _state === STATE.PAN && ! _this.noPan ) {
_panEnd.copy( getMouseOnScreen( event.pageX, event.pageY ) );
}
}
//鼠标弹出
function mouseup( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
_state = STATE.NONE;
document.removeEventListener( 'mousemove', mousemove );
document.removeEventListener( 'mouseup', mouseup );
_this.dispatchEvent( endEvent );
}
//鼠标滚轮
function mousewheel( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
switch ( event.deltaMode ) {
case 2:
// Zoom in pages
_zoomStart.y -= event.deltaY * 0.025;
break;
case 1:
// Zoom in lines
_zoomStart.y -= event.deltaY * 0.01;
break;
default:
// undefined, 0, assume pixels
_zoomStart.y -= event.deltaY * 0.00025;
break;
}
_this.dispatchEvent( startEvent );
_this.dispatchEvent( endEvent );
}
//触摸开始
function touchstart( event ) {
if ( _this.enabled === false ) return;
switch ( event.touches.length ) {
case 1:
_state = STATE.TOUCH_ROTATE;
_moveCurr.copy( getMouseOnCircle( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
_movePrev.copy( _moveCurr );
break;
default: // 2 or more
_state = STATE.TOUCH_ZOOM_PAN;
var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;
_touchZoomDistanceEnd = _touchZoomDistanceStart = Math.sqrt( dx * dx + dy * dy );
var x = ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX ) / 2;
var y = ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY ) / 2;
_panStart.copy( getMouseOnScreen( x, y ) );
_panEnd.copy( _panStart );
break;
}
_this.dispatchEvent( startEvent );
}
//触摸移动
function touchmove( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
switch ( event.touches.length ) {
case 1:
_movePrev.copy( _moveCurr );
_moveCurr.copy( getMouseOnCircle( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
break;
default: // 2 or more
var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;
_touchZoomDistanceEnd = Math.sqrt( dx * dx + dy * dy );
var x = ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX ) / 2;
var y = ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY ) / 2;
_panEnd.copy( getMouseOnScreen( x, y ) );
break;
}
}
//触摸
function touchend( event ) {
if ( _this.enabled === false ) return;
switch ( event.touches.length ) {
case 0:
_state = STATE.NONE;
break;
case 1:
_state = STATE.TOUCH_ROTATE;
_moveCurr.copy( getMouseOnCircle( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
_movePrev.copy( _moveCurr );
break;
}
_this.dispatchEvent( endEvent );
}
function contextmenu( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
}
//释放
this.dispose = function() {
this.domElement.removeEventListener( 'contextmenu', contextmenu, false );
this.domElement.removeEventListener( 'mousedown', mousedown, false );
this.domElement.removeEventListener( 'wheel', mousewheel, false );
this.domElement.removeEventListener( 'touchstart', touchstart, false );
this.domElement.removeEventListener( 'touchend', touchend, false );
this.domElement.removeEventListener( 'touchmove', touchmove, false );
document.removeEventListener( 'mousemove', mousemove, false );
document.removeEventListener( 'mouseup', mouseup, false );
window.removeEventListener( 'keydown', keydown, false );
window.removeEventListener( 'keyup', keyup, false );
};
this.domElement.addEventListener( 'contextmenu', contextmenu, false );
this.domElement.addEventListener( 'mousedown', mousedown, false );
this.domElement.addEventListener( 'wheel', mousewheel, false );
this.domElement.addEventListener( 'touchstart', touchstart, false );
this.domElement.addEventListener( 'touchend', touchend, false );
this.domElement.addEventListener( 'touchmove', touchmove, false );
window.addEventListener( 'keydown', keydown, false );
window.addEventListener( 'keyup', keyup, false );
this.handleResize();
// force an update at start
this.update();
};2.主要的难点就在于事件的处理与内容的渲染render，至于camera，scene，light部分，知道是什么内容和含义即可。
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