前面文章加载的底图数据是一种栅格数据,还有一种很重要的地理信息表现形式是矢量数据。在osgEarth中,这部分包含的内容仍是很丰富的,这里就总结一二。html
在《osgEarth使用笔记1——显示一个数字地球》这篇文章中代码的基础之上,添加加载显示矢量的代码:ios
#include <Windows.h> #include <iostream> #include <string> #include <osgViewer/Viewer> #include <osgDB/ReadFile> #include <osgEarth/MapNode> #include <osgEarth/ImageLayer> #include <osgEarthDrivers/gdal/GDALOptions> #include <osgEarthDrivers/cache_filesystem/FileSystemCache> #include <osgEarthDrivers/feature_ogr/OGRFeatureOptions> #include <osgEarthFeatures/FeatureSourceLayer> #include <osgEarthFeatures/FeatureModelLayer> #include <osgEarthUtil/EarthManipulator> using namespace std; void AddVector(osg::ref_ptr<osgEarth::Map> map) { // std::string filePath = "D:/Work/OSGNewBuild/osgearth-2.10.1/data/world.shp"; osgEarth::Drivers::OGRFeatureOptions featureData; featureData.url() = filePath; // 若是缺乏空间参考,能够手动指定 // ifstream infile("C:/Data/vector/hs/23.prj"); // string line; // getline(infile, line); // featureData.profile()->srsString() = line; // Make a feature source layer and add it to the Map: osgEarth::Features::FeatureSourceLayerOptions ogrLayer; ogrLayer.name() = filePath + "_source"; ogrLayer.featureSource() = featureData; osgEarth::Features::FeatureSourceLayer* featureSourceLayer = new osgEarth::Features::FeatureSourceLayer(ogrLayer); map->addLayer(featureSourceLayer); osgEarth::Features::FeatureSource *features = featureSourceLayer->getFeatureSource(); if (!features) { printf(("没法打开该矢量文件!")); return; } // osgEarth::Features::FeatureModelLayerOptions fmlOpt; fmlOpt.name() = filePath; fmlOpt.featureSourceLayer() = filePath + "_source"; fmlOpt.enableLighting() = false; osg::ref_ptr<osgEarth::Features::FeatureModelLayer> fml = new osgEarth::Features::FeatureModelLayer(fmlOpt); map->addLayer(fml); } int main() { osgEarth::ProfileOptions profileOpts; //地图配置:设置缓存目录 osgEarth::Drivers::FileSystemCacheOptions cacheOpts; string cacheDir = "D:/Work/OSGNewBuild/tmp"; cacheOpts.rootPath() = cacheDir; // osgEarth::MapOptions mapOpts; mapOpts.cache() = cacheOpts; mapOpts.profile() = profileOpts; //建立地图节点 osg::ref_ptr<osgEarth::Map> map = new osgEarth::Map(mapOpts); osg::ref_ptr<osgEarth::MapNode> mapNode = new osgEarth::MapNode(map); osgEarth::Drivers::GDALOptions gdal; gdal.url() = "D:/Work/OSGNewBuild/osgearth-2.10.1/data/world.tif"; osg::ref_ptr<osgEarth::ImageLayer> layer = new osgEarth::ImageLayer("BlueMarble", gdal); map->addLayer(layer); AddVector(map); osgViewer::Viewer viewer; viewer.setSceneData(mapNode); osg::ref_ptr< osgEarth::Util::EarthManipulator> mainManipulator = new osgEarth::Util::EarthManipulator; viewer.setCameraManipulator(mainManipulator); viewer.setUpViewInWindow(100, 100, 800, 600); return viewer.run(); }
osgEarth表达矢量的基本思路是,先将其读取到矢量源图层FeatureSourceLayer中,这个图层加载到osgEarth的图层列表中是不显示的,必须得再加载一个专门的符号化图层,将其符号号,才能正常显示。这里使用的是FeatureModelLayer,也就是将这个矢量当成模型来加载。运行这段程序显示结果以下:
缓存
这个矢量加载的是osgEarth自带的矢量地图world.shp,是一个面矢量,可是显示的效果却不太正确,也是由于没有设置合适的符号化方式。测试
矢量符号化在osgEarth中被抽象成了相似于CSS中样式表StyleSheet,能够在其中加载样式Style:字体
//设置样式 osgEarth::Symbology::Style style; //具体设置 //... // osgEarth::Features::FeatureModelLayerOptions fmlOpt; fmlOpt.name() = filePath; fmlOpt.featureSourceLayer() = filePath + "_source"; fmlOpt.enableLighting() = false; fmlOpt.styles() = new osgEarth::Symbology::StyleSheet(); fmlOpt.styles()->addStyle(style); osg::ref_ptr<osgEarth::Features::FeatureModelLayer> fml = new osgEarth::Features::FeatureModelLayer(fmlOpt); map->addLayer(fml);
设置是否启用深度测试:ui
//可见性 osgEarth::Symbology::RenderSymbol* rs = style.getOrCreate<osgEarth::Symbology::RenderSymbol>(); rs->depthTest() = false;
//贴地设置 osgEarth::Symbology::AltitudeSymbol* alt = style.getOrCreate<osgEarth::Symbology::AltitudeSymbol>(); alt->clamping() = alt->CLAMP_TO_TERRAIN; alt->technique() = alt->TECHNIQUE_DRAPE;
osgEarth有三种设置高度的方式,分别是:贴地,相对高程和绝对高程。我这里是将其设置为贴地。
编码
矢量贴地有多种技术实现方式,对每一种状况来讲,并不存在一种最好的方式,须要根据实际的状况去设置,具体的技术说明能够参考osgEarth文档:
url
接下来就是设置具体的样式了。这个矢量是个面矢量,因此给它设置一个面的样式,包含边界线和填充效果:spa
//设置矢量面样式(包括边界线) osgEarth::Symbology::LineSymbol* ls = style.getOrCreateSymbol<osgEarth::Symbology::LineSymbol>(); ls->stroke()->color() = osgEarth::Symbology::Color("#FA8072"); ls->stroke()->width() = 1.0; ls->tessellationSize()->set(100, osgEarth::Units::KILOMETERS); osgEarth::Symbology::PolygonSymbol *polygonSymbol = style.getOrCreateSymbol<osgEarth::Symbology::PolygonSymbol>(); polygonSymbol->fill()->color() = osgEarth::Symbology::Color(152.0f / 255, 251.0f / 255, 152.0f / 255, 0.8f); //238 230 133 polygonSymbol->outline() = true;
能够将矢量中存储的字段做为注记,标注在地图中。这时能够另外新建一个FeatureModelLayer图层,而且仍是会用到之间已经读取好的FeatureSourceLayer,只不过显示的样式修改成文字样式TextSymbol:3d
void AddAnno(std::string filePath, osg::ref_ptr<osgEarth::Map> map) { osgEarth::Symbology::Style labelStyle; osgEarth::Symbology::TextSymbol* text = labelStyle.getOrCreateSymbol<osgEarth::Symbology::TextSymbol>(); string name = "[CNTRY_NAME]"; //若是须要显示汉字,则须要转换成UTF-8编码 text->content() = osgEarth::Symbology::StringExpression(name); text->priority() = osgEarth::NumericExpression( "[pop_cntry]" ); text->size() = 16.0f; text->alignment() = osgEarth::Symbology::TextSymbol::ALIGN_CENTER_CENTER; text->fill()->color() = osgEarth::Symbology::Color::White; text->halo()->color() = osgEarth::Symbology::Color::Red; text->encoding() = osgEarth::Symbology::TextSymbol::ENCODING_UTF8; //string fontFile = PathRef::GetAppDir() + "/fonts/SourceHanSansCN-Regular.ttf"; //text->font() = fontFile; //若是显示汉字,须要支持中文字库的字体 // and configure a model layer: osgEarth::Features::FeatureModelLayerOptions fmlOpt; fmlOpt.name() = filePath + "_labels"; fmlOpt.featureSourceLayer() = filePath + "_source"; fmlOpt.styles() = new osgEarth::Symbology::StyleSheet(); fmlOpt.styles()->addStyle(labelStyle); osg::ref_ptr<osgEarth::Features::FeatureModelLayer> fml = new osgEarth::Features::FeatureModelLayer(fmlOpt); map->addLayer(fml); }
注意osgEarth中显示汉字仍是很麻烦的,最好矢量和代码相关的设置都是UTF-8编码的。
在最后的结果中若是线要素或者其余特征要素仍是没法渲染,那么可能就是须要初始化状态设置:
//解决Lines or Annotations (FeatureNode, etc.) 不被渲染的问题 osgEarth::GLUtils::setGlobalDefaults(viewer.getCamera()->getOrCreateStateSet());
这一点在osgEarth中被提到了:
整理的完整代码以下:
#include <Windows.h> #include <iostream> #include <string> #include <osgViewer/Viewer> #include <osgDB/ReadFile> #include <osgEarth/MapNode> #include <osgEarth/ImageLayer> #include <osgEarth/GLUtils> #include <osgEarthDrivers/gdal/GDALOptions> #include <osgEarthDrivers/cache_filesystem/FileSystemCache> #include <osgEarthDrivers/feature_ogr/OGRFeatureOptions> #include <osgEarthFeatures/FeatureSourceLayer> #include <osgEarthFeatures/FeatureModelLayer> #include <osgEarthUtil/EarthManipulator> using namespace std; void AddAnno(std::string filePath, osg::ref_ptr<osgEarth::Map> map) { osgEarth::Symbology::Style labelStyle; osgEarth::Symbology::TextSymbol* text = labelStyle.getOrCreateSymbol<osgEarth::Symbology::TextSymbol>(); string name = "[CNTRY_NAME]"; //若是须要显示汉字,则须要转换成UTF-8编码 text->content() = osgEarth::Symbology::StringExpression(name); text->priority() = osgEarth::NumericExpression( "[pop_cntry]" ); text->size() = 16.0f; text->alignment() = osgEarth::Symbology::TextSymbol::ALIGN_CENTER_CENTER; text->fill()->color() = osgEarth::Symbology::Color::White; text->halo()->color() = osgEarth::Symbology::Color::Red; text->encoding() = osgEarth::Symbology::TextSymbol::ENCODING_UTF8; //string fontFile = PathRef::GetAppDir() + "/fonts/SourceHanSansCN-Regular.ttf"; //text->font() = fontFile; //若是显示汉字,须要支持中文字库的字体 // and configure a model layer: osgEarth::Features::FeatureModelLayerOptions fmlOpt; fmlOpt.name() = filePath + "_labels"; fmlOpt.featureSourceLayer() = filePath + "_source"; fmlOpt.styles() = new osgEarth::Symbology::StyleSheet(); fmlOpt.styles()->addStyle(labelStyle); osg::ref_ptr<osgEarth::Features::FeatureModelLayer> fml = new osgEarth::Features::FeatureModelLayer(fmlOpt); map->addLayer(fml); } void AddVector(osg::ref_ptr<osgEarth::Map> map) { // std::string filePath = "D:/Work/OSGNewBuild/osgearth-2.10.1/data/world.shp"; osgEarth::Drivers::OGRFeatureOptions featureData; featureData.url() = filePath; // 若是缺乏空间参考,能够手动指定 // ifstream infile("C:/Data/vector/hs/23.prj"); // string line; // getline(infile, line); // featureData.profile()->srsString() = line; // Make a feature source layer and add it to the Map: osgEarth::Features::FeatureSourceLayerOptions ogrLayer; ogrLayer.name() = filePath + "_source"; ogrLayer.featureSource() = featureData; osgEarth::Features::FeatureSourceLayer* featureSourceLayer = new osgEarth::Features::FeatureSourceLayer(ogrLayer); map->addLayer(featureSourceLayer); osgEarth::Features::FeatureSource *features = featureSourceLayer->getFeatureSource(); if (!features) { printf(("没法打开该矢量文件!")); return; } //设置样式 osgEarth::Symbology::Style style; //可见性 osgEarth::Symbology::RenderSymbol* rs = style.getOrCreate<osgEarth::Symbology::RenderSymbol>(); rs->depthTest() = false; //贴地设置 osgEarth::Symbology::AltitudeSymbol* alt = style.getOrCreate<osgEarth::Symbology::AltitudeSymbol>(); alt->clamping() = alt->CLAMP_TO_TERRAIN; alt->technique() = alt->TECHNIQUE_DRAPE; //设置矢量面样式(包括边界线) osgEarth::Symbology::LineSymbol* ls = style.getOrCreateSymbol<osgEarth::Symbology::LineSymbol>(); ls->stroke()->color() = osgEarth::Symbology::Color("#FA8072"); ls->stroke()->width() = 1.0; ls->tessellationSize()->set(100, osgEarth::Units::KILOMETERS); osgEarth::Symbology::PolygonSymbol *polygonSymbol = style.getOrCreateSymbol<osgEarth::Symbology::PolygonSymbol>(); polygonSymbol->fill()->color() = osgEarth::Symbology::Color(152.0f / 255, 251.0f / 255, 152.0f / 255, 0.8f); //238 230 133 polygonSymbol->outline() = true; // osgEarth::Features::FeatureModelLayerOptions fmlOpt; fmlOpt.name() = filePath; fmlOpt.featureSourceLayer() = filePath + "_source"; fmlOpt.enableLighting() = false; fmlOpt.styles() = new osgEarth::Symbology::StyleSheet(); fmlOpt.styles()->addStyle(style); osg::ref_ptr<osgEarth::Features::FeatureModelLayer> fml = new osgEarth::Features::FeatureModelLayer(fmlOpt); map->addLayer(fml); AddAnno(filePath, map); } int main() { osgEarth::ProfileOptions profileOpts; //地图配置:设置缓存目录 osgEarth::Drivers::FileSystemCacheOptions cacheOpts; string cacheDir = "D:/Work/OSGNewBuild/tmp"; cacheOpts.rootPath() = cacheDir; // osgEarth::MapOptions mapOpts; mapOpts.cache() = cacheOpts; mapOpts.profile() = profileOpts; //建立地图节点 osg::ref_ptr<osgEarth::Map> map = new osgEarth::Map(mapOpts); osg::ref_ptr<osgEarth::MapNode> mapNode = new osgEarth::MapNode(map); osgEarth::Drivers::GDALOptions gdal; gdal.url() = "D:/Work/OSGNewBuild/osgearth-2.10.1/data/world.tif"; osg::ref_ptr<osgEarth::ImageLayer> layer = new osgEarth::ImageLayer("BlueMarble", gdal); map->addLayer(layer); AddVector(map); osgViewer::Viewer viewer; viewer.setSceneData(mapNode); osg::ref_ptr< osgEarth::Util::EarthManipulator> mainManipulator = new osgEarth::Util::EarthManipulator; viewer.setCameraManipulator(mainManipulator); //解决Lines or Annotations (FeatureNode, etc.) 不被渲染的问题 osgEarth::GLUtils::setGlobalDefaults(viewer.getCamera()->getOrCreateStateSet()); viewer.setUpViewInWindow(100, 100, 800, 600); return viewer.run(); }
最后的显示结果:
osgEarth中矢量符号化的样式机制很是强大,甚至能够将面按照线绘制,线按照点来绘制。可是这样就会形成一个问题,那就是矢量类型若是判断不正确,渲染的效果就不正确,除非事先知道是点、线或者面。能够从矢量图层中获取到FeatureSource这个类,存在的getGeometryType()接口获取的类型有时候不太正确(有时候返回成osgEarth::Symbology::Geometry::TYPE_UNKNOWN)。
一直困扰的两个问题就来了:
这两个问题估计只能留待之后解决了。