osgearth_city例子总结

转自：http://blog.csdn.net/taor1/article/details/8242480

int main(int argc, char** argv)

{

osg::ArgumentParser arguments(&argc,argv);

// create the map.

Map* map = new Map();

// add a TMS imagery layer:

TMSOptions imagery;

imagery.url() = "http://readymap.org/readymap/tiles/1.0.0/22/";

map->addImageLayer( new ImageLayer("ReadyMap imagery", imagery) );

// create a feature source to load the building footprint shapefile.

OGRFeatureOptions feature_opt;

feature_opt.name() = "buildings";

feature_opt.url() = "../data/boston_buildings_utm19.shp";

feature_opt.buildSpatialIndex() = true;

// a style for the building data:

Style buildingStyle;

buildingStyle.setName( "default" );

ExtrusionSymbol* extrusion = buildingStyle.getOrCreate();

extrusion->heightexpression_r() = Numericexpression_r( "3.5 * max( [story_ht_], 1 )" );

extrusion->flatten() = true;

extrusion->wallStyleName() = "building-wall";

extrusion->roofStyleName() = "building-roof";

// a style for the wall textures:

Style wallStyle;

wallStyle.setName( "building-wall" );

SkinSymbol* wallSkin = wallStyle.getOrCreate();

wallSkin->libraryName() = "us_resources";

wallSkin->addTag( "building" );

wallSkin->randomSeed() = 1;

// a style for the rooftop textures:

Style roofStyle;

roofStyle.setName( "building-roof" );

SkinSymbol* roofSkin = roofStyle.getOrCreate();

roofSkin->libraryName() = "us_resources";

roofSkin->addTag( "rooftop" );

roofSkin->randomSeed() = 1;

roofSkin->isTiled() = true;

// assemble a stylesheet and add our styles to it:

StyleSheet* styleSheet = new StyleSheet();

styleSheet->addStyle( buildingStyle );

styleSheet->addStyle( wallStyle );

styleSheet->addStyle( roofStyle );

// load a resource library that contains the building textures.

ResourceLibrary* reslib =

new ResourceLibrary( "us_resources", "../data/resources/textures_us/catalog.xml" );

styleSheet->addResourceLibrary( reslib );

// set up a paging layout for incremental loading.

FeatureDisplayLayout layout;

layout.tileSizeFactor() = 45.0;

layout.addLevel( FeatureLevel(0.0f, 20000.0f) );

// create a model layer that will render the buildings according to our style sheet.

FeatureGeomModelOptions fgm_opt;

fgm_opt.featureOptions() = feature_opt;

fgm_opt.styles() = styleSheet;

fgm_opt.layout() = layout;

map->addModelLayer( new ModelLayer( "buildings", fgm_opt ) );

// initialize a viewer:

osgViewer::Viewer viewer(arguments);

EarthManipulator* manip = new EarthManipulator();

viewer.setCameraManipulator( manip );

// make the map scene graph:

osg::Group* root = new osg::Group();

viewer.setSceneData( root );

MapNode* mapNode = new MapNode( map );

root->addChild( mapNode );

// Process cmdline args

MapNodeHelper helper;

helper.configureView( &viewer );

//在configureView中加入了

// add some stock OSG handlers:

//view->addEventHandler(new osgViewer::StatsHandler());

//view->addEventHandler(new osgViewer::WindowSizeHandler());

//view->addEventHandler(new osgViewer::ThreadingHandler());

//view->addEventHandler(new osgViewer::LODScaleHandler());

//view->addEventHandler(new osgGA::StateSetManipulator(view->getCamera()->getOrCreateStateSet()));

// osgEarth benefits from pre-compilation of GL objects in the pager. In newer versions of

// OSG, this activates OSG's IncrementalCompileOpeartion in order to avoid frame breaks.

//view->getDatabasePager()->setDoPreCompile( true );

helper.parse(mapNode, arguments, &viewer, root, new LabelControl("City Demo"));

//处理控制台命令

// zoom to a good startup position

manip->setViewpoint( Viewpoint(-71.0763, 42.34425, 0, 24.261, -21.6, 3450.0), 5.0 );

viewer.getDatabasePager()->setDoPreCompile( true );

viewer.getCamera()->addCullCallback( new AutoClipPlaneCullCallback(mapNode) );

return viewer.run();

}

1、Map* map=new Map();//创建一个地图

TMSOptions imagery;//图像层

imagery.url() = "http://readymap.org/readymap/tiles/1.0.0/22/";

map->addImageLayer(new ImageLayer("....",imagery));//加入该层

2、得到建筑物的矢量轮廓

OGRFeatureOptions feature_opt;

feature_opt.name()="buildings";

feature_opt.url()=".....shp";//矢量文件路径

feature_opt.buildSpatialIndex()=true;//构建空间索引，既然是索引，感觉是不是应该提速的。？？？

3、建筑物的风格

Style buildingStyle;

buildingStyle.setName("default");

ExtrusionSymbol* extrusion=buildingStyle.getOrCreate();

extrusion->height()=Numericexpression_r(3.5*max([story_ht_],1));//这应该是把建筑物拔高的

extrusion->flatten()=true;//这应该是是屋顶平的

extrusion->wallStyleName()="building_wall";//墙的风格名

extrusion->roofStyleName()="building_roof";//屋顶的风格名

4、墙的纹理

Style wallStyle;

wallStyle.setName("building_wall");

SkinSymbol* wallSkin=wallStyle.getOrCreate();

wallSkin->libraryName()="us_resource";//资源库名

wallSkin->addTag("building");//用资源库中building标签

wallSkin->randomSeed()=1;在多个building中随机取值

5、房顶纹理

// a style for the rooftop textures:

Style roofStyle;

roofStyle.setName( "building-roof" );

SkinSymbol* roofSkin = roofStyle.getOrCreate();

roofSkin->libraryName() = "us_resources";

roofSkin->addTag( "rooftop" );

roofSkin->randomSeed() = 1;

roofSkin->isTiled() = true;//进行分块

6、组装style

// assemble a stylesheet and add our styles to it:

StyleSheet* styleSheet = new StyleSheet();

styleSheet->addStyle( buildingStyle );

styleSheet->addStyle( wallStyle );

styleSheet->addStyle( roofStyle );

7、加载资源库

ResourceLibrary* resLib=new ResourceLibrary("us_resource","../data/resources/textures_us/catalog.xml");

8、对页面进行分块，加快加载

FeatureDisplayLayout layout;

layout.tileSizeFactor()=45.0;//分成45块

layout.addLevel(FeatureLevel(0.0,20000.0));范围是0-20000.0，所以每块大小为20000.0/45.0

9、现在在图像层上，加入建筑物层

FeatureGeomModelOptions fgm_opt;

fgm_opt.layout()=layout;

fgm_opt.styles()=styleSheet;

fgm_opt.featureOptions()=feature_opt;

map->addModelLayer(new ModelLayer("building",fgm_opt));

10、加入场景