君子性非异也，善假于物也 - Threejs 引入TrackballControls 查看场景
太阳火神的漂亮人生 (http://blog.csdn.net/opengl_es)
本文遵循“署名-非商业用途-保持一致”创作公用协议
下面为 html 源文件里引入 TrackballControls 库的关键代码，当中 camera 和 renderer 须要对 Threejs 有所了解方可理解：
<script>
var controls;
controls = new THREE.TrackballControls( camera, renderer.domElement );
function animate() {
requestAnimationFrame( animate, renderer.domElement );
controls.update();
renderer.render( scene, camera );
}
</script>
下面代码归原作者全部，但在下面所署两网址未找到与此一致的最新代码，而有一些相似的可用代码，能够參考一下。
上面代码中引用的 js/controls/TrackballControls.js 代码原文，可拷贝可新建 TrackballControls.js 引入，并按上面方式使用就可以：
/**
* @author Eberhard Graether / http://egraether.com/
* @author Mark Lundin / http://mark-lundin.com
*/
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, 0, height: 0 };
this.rotateSpeed = 1.0;
this.zoomSpeed = 1.2;
this.panSpeed = 0.3;
this.noRotate = false;
this.noZoom = false;
this.noPan = false;
this.noRoll = 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(),
_rotateStart = new THREE.Vector3(),
_rotateEnd = new THREE.Vector3(),
_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
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 );
}
};
var getMouseOnScreen = ( function () {
var vector = new THREE.Vector2();
return function ( pageX, pageY ) {
vector.set(
( pageX - _this.screen.left ) / _this.screen.width,
( pageY - _this.screen.top ) / _this.screen.height
);
return vector;
};
}() );
var getMouseProjectionOnBall = ( function () {
var vector = new THREE.Vector3();
var objectUp = new THREE.Vector3();
var mouseOnBall = new THREE.Vector3();
return function ( pageX, pageY ) {
mouseOnBall.set(
( pageX - _this.screen.width * 0.5 - _this.screen.left ) / (_this.screen.width*.5),
( _this.screen.height * 0.5 + _this.screen.top - pageY ) / (_this.screen.height*.5),
0.0
);
var length = mouseOnBall.length();
if ( _this.noRoll ) {
if ( length < Math.SQRT1_2 ) {
mouseOnBall.z = Math.sqrt( 1.0 - length*length );
} else {
mouseOnBall.z = .5 / length;
}
} else if ( length > 1.0 ) {
mouseOnBall.normalize();
} else {
mouseOnBall.z = Math.sqrt( 1.0 - length * length );
}
_eye.copy( _this.object.position ).sub( _this.target );
vector.copy( _this.object.up ).setLength( mouseOnBall.y )
vector.add( objectUp.copy( _this.object.up ).cross( _eye ).setLength( mouseOnBall.x ) );
vector.add( _eye.setLength( mouseOnBall.z ) );
return vector;
};
}() );
this.rotateCamera = (function(){
var axis = new THREE.Vector3(),
quaternion = new THREE.Quaternion();
return function () {
var angle = Math.acos( _rotateStart.dot( _rotateEnd ) / _rotateStart.length() / _rotateEnd.length() );
if ( angle ) {
axis.crossVectors( _rotateStart, _rotateEnd ).normalize();
angle *= _this.rotateSpeed;
quaternion.setFromAxisAngle( axis, -angle );
_eye.applyQuaternion( quaternion );
_this.object.up.applyQuaternion( quaternion );
_rotateEnd.applyQuaternion( quaternion );
if ( _this.staticMoving ) {
_rotateStart.copy( _rotateEnd );
} else {
quaternion.setFromAxisAngle( axis, angle * ( _this.dynamicDampingFactor - 1.0 ) );
_rotateStart.applyQuaternion( quaternion );
}
}
}
}());
this.zoomCamera = function () {
if ( _state === STATE.TOUCH_ZOOM_PAN ) {
var factor = _touchZoomDistanceStart / _touchZoomDistanceEnd;
_touchZoomDistanceStart = _touchZoomDistanceEnd;
_eye.multiplyScalar( factor );
} else {
var 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 () {
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 ) );
}
}
}
}());
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 ) );
}
if ( _eye.lengthSq() < _this.minDistance * _this.minDistance ) {
_this.object.position.addVectors( _this.target, _eye.setLength( _this.minDistance ) );
}
}
};
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 );
}
};
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
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;
}
}
function keyup( event ) {
if ( _this.enabled === false ) return;
_state = _prevState;
window.addEventListener( 'keydown', keydown, false );
}
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 ) {
_rotateStart.copy( getMouseProjectionOnBall( event.pageX, event.pageY ) );
_rotateEnd.copy( _rotateStart );
} 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 );
}
function mousemove( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
if ( _state === STATE.ROTATE && !_this.noRotate ) {
_rotateEnd.copy( getMouseProjectionOnBall( 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 ) );
}
}
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 );
}
function mousewheel( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
var delta = 0;
if ( event.wheelDelta ) { // WebKit / Opera / Explorer 9
delta = event.wheelDelta / 40;
} else if ( event.detail ) { // Firefox
delta = - event.detail / 3;
}
_zoomStart.y += delta * 0.01;
_this.dispatchEvent( startEvent );
_this.dispatchEvent( endEvent );
}
function touchstart( event ) {
if ( _this.enabled === false ) return;
switch ( event.touches.length ) {
case 1:
_state = STATE.TOUCH_ROTATE;
_rotateStart.copy( getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
_rotateEnd.copy( _rotateStart );
break;
case 2:
_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;
default:
_state = STATE.NONE;
}
_this.dispatchEvent( startEvent );
}
function touchmove( event ) {
if ( _this.enabled === false ) return;
event.preventDefault();
event.stopPropagation();
switch ( event.touches.length ) {
case 1:
_rotateEnd.copy( getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
break;
case 2:
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;
default:
_state = STATE.NONE;
}
}
function touchend( event ) {
if ( _this.enabled === false ) return;
switch ( event.touches.length ) {
case 1:
_rotateEnd.copy( getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
_rotateStart.copy( _rotateEnd );
break;
case 2:
_touchZoomDistanceStart = _touchZoomDistanceEnd = 0;
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 ) );
_panStart.copy( _panEnd );
break;
}
_state = STATE.NONE;
_this.dispatchEvent( endEvent );
}
this.domElement.addEventListener( 'contextmenu', function ( event ) { event.preventDefault(); }, false );
this.domElement.addEventListener( 'mousedown', mousedown, false );
this.domElement.addEventListener( 'mousewheel', mousewheel, false );
this.domElement.addEventListener( 'DOMMouseScroll', mousewheel, false ); // firefox
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();
};
THREE.TrackballControls.prototype = Object.create( THREE.EventDispatcher.prototype );