基于WebGL的三维地形渲染
1.生成WebMap页面
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import subprocess from jinja2 import Environment, FileSystemLoader # Create our DEM #将DEM数据转化为ENVI的bin格式（一个头文件xml与一个数据文件bin）
# use gdal_translate command to create an image to store elevation values
# -scale from 0 meters to 2625 meters
# stretch all values to full 16bit 0 to 65535
# -ot is output type = UInt16 unsigned 16bit
# -outsize is 200 x 200 px
# -of is output format ENVI raster image .bin file type
# then our input .tif with elevation
# followed by output file name .bin
subprocess.call("gdal_translate -scale 0 2625 0 65535 "
"-ot UInt16 -outsize 200 200 -of ENVI "
"../../ch07/geodata/dem_3857.tif "
"../geodata/whistler2.bin") #Jinja2是基于python的模板引擎
# create our Jinja2 HTML
# create a standard Jinja2 Environment and load all files
# located in the folder templates
env = Environment(loader=FileSystemLoader(["../www/templates"])) # define which template we want to render
template = env.get_template("base-3d-map.html") # path and name of input 16bit raster image with our elevation values
dem_3d = "../../geodata/whistler2.bin" # name and location of the output html file we will generate
out_html = "../www/html/ch10-03_dem3d_map.html"
#生成页面
# dem_file is the variable name we use in our Jinja2 html template file
result = template.render(title="Threejs DEM Viewer", dem_file=dem_3d) # write out our template to the html file on disk
with open(out_html,mode="w") as f:
f.write(result)
2.将数据与页面复制Web服务器的相关目录下
3.访问WebMap页面
4.相关代码
1）three.min.js
略
2）TerrainLoader.js
/**
* @author Bjorn Sandvik / http://thematicmapping.org/
*/ THREE.TerrainLoader = function ( manager ) { this.manager = ( manager !== undefined ) ? manager : THREE.DefaultLoadingManager; }; THREE.TerrainLoader.prototype = { constructor: THREE.TerrainLoader, load: function ( url, onLoad, onProgress, onError ) { var scope = this;
var request = new XMLHttpRequest(); if ( onLoad !== undefined ) { request.addEventListener( 'load', function ( event ) { onLoad( new Uint16Array( event.target.response ) );
scope.manager.itemEnd( url ); }, false ); } if ( onProgress !== undefined ) { request.addEventListener( 'progress', function ( event ) { onProgress( event ); }, false ); } if ( onError !== undefined ) { request.addEventListener( 'error', function ( event ) { onError( event ); }, false ); } if ( this.crossOrigin !== undefined ) request.crossOrigin = this.crossOrigin; request.open( 'GET', url, true ); request.responseType = 'arraybuffer'; request.send( null ); scope.manager.itemStart( url ); }, setCrossOrigin: function ( value ) { this.crossOrigin = value; } };
3）TrackballControls.js
/**
* @author Eberhard Graether / http://egraether.com/
*/ THREE.TrackballControls = function ( object, domElement ) { var _this = this;
var STATE = { NONE: -1, ROTATE: 0, ZOOM: 1, PAN: 2, TOUCH_ROTATE: 3, TOUCH_ZOOM: 4, TOUCH_PAN: 5 }; this.object = object;
this.domElement = ( domElement !== undefined ) ? domElement : document; // API this.enabled = true; this.screen = { width: 0, height: 0, offsetLeft: 0, offsetTop: 0 };
this.radius = ( this.screen.width + this.screen.height ) / 4; 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 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' }; // methods this.handleResize = function () { this.screen.width = window.innerWidth;
this.screen.height = window.innerHeight; this.screen.offsetLeft = 0;
this.screen.offsetTop = 0; this.radius = ( this.screen.width + this.screen.height ) / 4; }; this.handleEvent = function ( event ) { if ( typeof this[ event.type ] == 'function' ) { this[ event.type ]( event ); } }; this.getMouseOnScreen = function ( clientX, clientY ) { return new THREE.Vector2(
( clientX - _this.screen.offsetLeft ) / _this.radius * 0.5,
( clientY - _this.screen.offsetTop ) / _this.radius * 0.5
); }; this.getMouseProjectionOnBall = function ( clientX, clientY ) { var mouseOnBall = new THREE.Vector3(
( clientX - _this.screen.width * 0.5 - _this.screen.offsetLeft ) / _this.radius,
( _this.screen.height * 0.5 + _this.screen.offsetTop - clientY ) / _this.radius,
0.0
); var length = mouseOnBall.length(); if ( length > 1.0 ) { mouseOnBall.normalize(); } else { mouseOnBall.z = Math.sqrt( 1.0 - length * length ); } _eye.copy( _this.object.position ).sub( _this.target ); var projection = _this.object.up.clone().setLength( mouseOnBall.y );
projection.add( _this.object.up.clone().cross( _eye ).setLength( mouseOnBall.x ) );
projection.add( _eye.setLength( mouseOnBall.z ) ); return projection; }; this.rotateCamera = function () { var angle = Math.acos( _rotateStart.dot( _rotateEnd ) / _rotateStart.length() / _rotateEnd.length() ); if ( angle ) { var axis = ( new THREE.Vector3() ).crossVectors( _rotateStart, _rotateEnd ).normalize();
quaternion = new THREE.Quaternion(); 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 ) { 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 = _panEnd.clone().sub( _panStart ); if ( mouseChange.lengthSq() ) { mouseChange.multiplyScalar( _eye.length() * _this.panSpeed ); var pan = _eye.clone().cross( _this.object.up ).setLength( mouseChange.x );
pan.add( _this.object.up.clone().setLength( mouseChange.y ) ); _this.object.position.add( pan );
_this.target.add( pan ); if ( _this.staticMoving ) { _panStart = _panEnd; } else { _panStart.add( mouseChange.subVectors( _panEnd, _panStart ).multiplyScalar( _this.dynamicDampingFactor ) ); } } }; this.checkDistances = function () { if ( !_this.noZoom || !_this.noPan ) { if ( _this.object.position.lengthSq() > _this.maxDistance * _this.maxDistance ) { _this.object.position.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 ) > 0 ) { _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 = _rotateEnd = _this.getMouseProjectionOnBall( event.clientX, event.clientY ); } else if ( _state === STATE.ZOOM && !_this.noZoom ) { _zoomStart = _zoomEnd = _this.getMouseOnScreen( event.clientX, event.clientY ); } else if ( _state === STATE.PAN && !_this.noPan ) { _panStart = _panEnd = _this.getMouseOnScreen( event.clientX, event.clientY ); } document.addEventListener( 'mousemove', mousemove, false );
document.addEventListener( 'mouseup', mouseup, false ); } function mousemove( event ) { if ( _this.enabled === false ) return; event.preventDefault();
event.stopPropagation(); if ( _state === STATE.ROTATE && !_this.noRotate ) { _rotateEnd = _this.getMouseProjectionOnBall( event.clientX, event.clientY ); } else if ( _state === STATE.ZOOM && !_this.noZoom ) { _zoomEnd = _this.getMouseOnScreen( event.clientX, event.clientY ); } else if ( _state === STATE.PAN && !_this.noPan ) { _panEnd = _this.getMouseOnScreen( event.clientX, event.clientY ); } } function mouseup( event ) { if ( _this.enabled === false ) return; event.preventDefault();
event.stopPropagation(); _state = STATE.NONE; document.removeEventListener( 'mousemove', mousemove );
document.removeEventListener( 'mouseup', mouseup ); } 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; } function touchstart( event ) { if ( _this.enabled === false ) return; switch ( event.touches.length ) { case 1:
_state = STATE.TOUCH_ROTATE;
_rotateStart = _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
break; case 2:
_state = STATE.TOUCH_ZOOM;
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 );
break; case 3:
_state = STATE.TOUCH_PAN;
_panStart = _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
break; default:
_state = STATE.NONE; } } function touchmove( event ) { if ( _this.enabled === false ) return; event.preventDefault();
event.stopPropagation(); switch ( event.touches.length ) { case 1:
_rotateEnd = _this.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 )
break; case 3:
_panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
break; default:
_state = STATE.NONE; } } function touchend( event ) { if ( _this.enabled === false ) return; switch ( event.touches.length ) { case 1:
_rotateStart = _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
break; case 2:
_touchZoomDistanceStart = _touchZoomDistanceEnd = 0;
break; case 3:
_panStart = _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
break; } _state = STATE.NONE; } 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(); }; THREE.TrackballControls.prototype = Object.create( THREE.EventDispatcher.prototype );
4）dem3d_map.html
<html lang="en">
<head>
<title>DEM threejs Browser</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
<style> body { margin: 0; overflow: hidden; }</style>
</head>
<body>
<div id="dem-map"></div>
<script src="../js/three.min.js"></script>
<script src="../js/TrackballControls.js"></script>
<script src="../js/TerrainLoader.js"></script>
<script> var width = window.innerWidth,
height = window.innerHeight; var scene = new THREE.Scene(); var axes = new THREE.AxisHelper(200);
scene.add(axes); var camera = new THREE.PerspectiveCamera(45, width / height, 0.1, 1000);
camera.position.set(0, -50, 50); var renderer = new THREE.WebGLRenderer();
renderer.setSize(width, height); var terrainLoader = new THREE.TerrainLoader();
terrainLoader.load('../../geodata/whistler2.bin', function(data) { var geometry = new THREE.PlaneGeometry(60, 60, 199, 199); for (var i = 0, l = geometry.vertices.length; i < l; i++) {
geometry.vertices[i].z = data[i] / 65535 * 10;
} var material = new THREE.MeshPhongMaterial({
color: 0xdddddd,
wireframe: true
}); /*
//加载纹理
var material = new THREE.MeshPhongMaterial({
map: THREE.ImageUtils.loadTexture('../../geodata/whistler_ortho_f.jpg')
});
*/
var plane = new THREE.Mesh(geometry, material);
scene.add(plane); }); var controls = new THREE.TrackballControls(camera); document.getElementById('dem-map').appendChild(renderer.domElement); render(); function render() {
controls.update();
requestAnimationFrame(render);
renderer.render(scene, camera);
} </script>
</body>
</html>
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