目录

效果

代码

代码分析

加载模式

---

效果

代码

#include "stdafx.h"
#include <osg/Notify>
#include <osgGA/StateSetManipulator>
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>

#include <osgEarth/MapNode>
#include <osgEarth/ImageLayer>
#include <osgEarth/ModelLayer>
#include <osgEarthUtil/ExampleResources>
#include <osgEarthUtil/EarthManipulator>

#include <osgEarthSymbology/Style>
#include <osgEarthFeatures/FeatureModelLayer>

#include <osgEarthDrivers/gdal/GDALOptions>
#include <osgEarthDrivers/feature_ogr/OGRFeatureOptions>
#include <osgEarthDrivers/agglite/AGGLiteOptions>

using namespace osgEarth;
using namespace osgEarth::Features;
using namespace osgEarth::Drivers;
using namespace osgEarth::Symbology;
using namespace osgEarth::Util;

int usage(const std::string& app)
{
	OE_NOTICE "\n" << app << "\n"	// 绘制特征的方法
		<< "  --rasterize           : draw features as rasterized image tiles \n" // 光栅化平铺瓦片图
		<< "  --drape               : draw features as projected texture \n"	// 投影纹理
		<< "  --clamp               : draw features using shader clamping \n"	// 使用贴地着色器
		<< "  --mem                 : load features from memory \n"				// 加载默认线
		<< "  --labels              : add feature labels \n"					// 添加文本标签
		<< "\n"
		<< MapNodeHelper().usage()
		<< std::endl;

	return 0;
}

//
// NOTE: run this sample from the repo/tests directory.
//
int main(int argc, char** argv)
{
	osg::ArgumentParser arguments(&argc, argv);

	if (arguments.read("--help"))
		return usage(argv[0]);

	// cmd执行命令时，输入： osgearth_featuresd.exe --rasterize --mem --labels --drape --clamp (一些参数)
	// 当输入了某个参数，则获取到的值为1，否则为0
	/*bool useRaster = arguments.read("--rasterize");
	bool useMem = arguments.read("--mem");
	bool useLabels = arguments.read("--labels");
	bool useDraping = arguments.read("--drape");
	bool useClamping = arguments.read("--clamp");*/
	bool useRaster = true;
	bool useMem = true;
	bool useLabels = true;
	bool useDraping = true;
	bool useClamping = true;
	std::cout << useRaster << useMem << useLabels << useDraping << useClamping << std::endl;

	osgViewer::Viewer viewer(arguments);

	// Start by creating the map:
	Map* map = new Map();

	// Start with a basemap imagery layer; we'll be using the GDAL driver
	// to load a local GeoTIFF file:
	// 添加默认地图
	GDALOptions basemap;// GDAL选项类，继承自TileSourceOptions
	basemap.url() = "../data/world.tif";
	map->addLayer(new ImageLayer(ImageLayerOptions("basemap", basemap)));

	// Next we add a feature layer. 
	// 添加shp文件
	OGRFeatureOptions featureData;
	if (!useMem)
	{
		// Configures the feature driver to load the vectors from a shapefile:
		// 如果给出相对路径，则国界线总是加载不上
		// 此处必须给全路径！！！
		featureData.url() = "F:\\point-cloud-lab-new\\PointCloudLab\\GeoEngine_output\\data\\world.shp";
		std::cout << "add world.shp" << std::endl;
	}
	else
	{
		// the --mem options tells us to just make an in-memory geometry:
		// 当没有 --mem参数时，采用默认的line绘制
		Ring* line = new Ring();
		line->push_back(osg::Vec3d(60, 20, 0));
		line->push_back(osg::Vec3d(120, 20, 0));
		line->push_back(osg::Vec3d(120, 60, 0));
		line->push_back(osg::Vec3d(60, 60, 0));
		featureData.geometry() = line;
		std::cout << "don't add world.shp" << std::endl;
	}

	// Make a feature source layer and add it to the Map:
	// 制作特征源图层并添加到map
	FeatureSourceLayerOptions ogrLayer;
	ogrLayer.name() = "vector-data";// 矢量数据
	ogrLayer.featureSource() = featureData;// shp 文件或者默认line
	map->addLayer(new FeatureSourceLayer(ogrLayer));

	// Define a style for the feature data. Since we are going to render the
	// vectors as lines, configure the line symbolizer:
	// 设置矢量面样式（包括边界线）
	Style style;

	LineSymbol* ls = style.getOrCreateSymbol<LineSymbol>();
	ls->stroke()->color() = Color::Yellow;
	ls->stroke()->width() = 2.0f;// 可以将线宽设置宽一些，更容易看出不同参数useDraping和useClamping产生的区别
	ls->tessellationSize()->set(100, Units::KILOMETERS);// 细分程度

	if (useDraping)//是否设置drape属性
	{
		AltitudeSymbol* alt = style.getOrCreate<AltitudeSymbol>();
		alt->clamping() = alt->CLAMP_TO_TERRAIN;
		alt->technique() = alt->TECHNIQUE_DRAPE;
		std::cout << "drape" << std::endl;
	}

	else if (useClamping)// 贴地属性
	{
		AltitudeSymbol* alt = style.getOrCreate<AltitudeSymbol>();
		alt->clamping() = alt->CLAMP_TO_TERRAIN;
		alt->technique() = alt->TECHNIQUE_GPU;
		// 线的细分程度
		ls->tessellationSize()->set(100, Units::KILOMETERS);

		RenderSymbol* render = style.getOrCreate<RenderSymbol>();
		render->depthOffset()->enabled() = true;
		render->depthTest() = false;
		std::cout << "no drape,but clamp" << std::endl;
	}

	if (useRaster)// 光栅化
	{
		AGGLiteOptions rasterOptions;
		rasterOptions.featureOptions() = featureData;
		rasterOptions.styles() = new StyleSheet();
		rasterOptions.styles()->addStyle(style);
		map->addLayer(new ImageLayer("My Features", rasterOptions));
		std::cout << "raster" << std::endl;
	}

	else //if (useGeom)
	{
		FeatureModelLayerOptions fml;
		fml.name() = "My Features";
		fml.featureSourceLayer() = "vector-data";
		fml.styles() = new StyleSheet();
		fml.styles()->addStyle(style);
		// fml.enableLighting() = false;

		map->addLayer(new FeatureModelLayer(fml));
		std::cout << "no raster" << std::endl;
	}

	if (useLabels && !useRaster)// 有标签且非光栅化
	{
		// set up symbology for drawing labels. We're pulling the label
		// text from the name attribute, and its draw priority from the
		// population attribute.
		// 设置文本样式
		Style labelStyle;

		TextSymbol* text = labelStyle.getOrCreateSymbol<TextSymbol>();
		text->content() = StringExpression("[cntry_name]");//如果需要显示汉字，则需要转换成UTF-8编码
		text->priority() = NumericExpression("[pop_cntry]");
		text->size() = 26.0f;// 字号有些大
		text->alignment() = TextSymbol::ALIGN_CENTER_CENTER;
		text->fill()->color() = Color::White;
		text->halo()->color() = Color::DarkGray;// 文字光环颜色

		// and configure a model layer:
		FeatureModelLayerOptions fml;
		fml.name() = "Labels";
		fml.featureSourceLayer() = "vector-data";
		fml.styles() = new StyleSheet();
		fml.styles()->addStyle(labelStyle);

		map->addLayer(new FeatureModelLayer(fml));
		std::cout << "no raster, but labels" << std::endl;
	}

	// That's it, the map is ready; now create a MapNode to render the Map:
	MapNode* mapNode = new MapNode(map);

	viewer.setSceneData(mapNode);
	viewer.setCameraManipulator(new EarthManipulator());

	// add some stock OSG handlers:
	MapNodeHelper().configureView(&viewer);

	return viewer.run();
}

代码分析

osgEarth表达矢量的基本思路是：

• 先将shp文件读取到矢量源图层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，将其符号化，才能正常显示。

 
 
1. 先声明基础地图
osgEarth::Drivers::GDALOptions basemap;
basemap.url() = "world.tif";
// 添加影像图到map节点
map->addLayer( new ImageLayer(ImageLayerOptions("basemap", basemap)));
 
 
2. 加载特征数据
osgEarth::Drivers::OGRFeatureOptions featureData;
featureData.url() = "world.shp";
// 特征源图层选项设置
osgEarth::Features::FeatureSourceLayerOptions ogrLayer;
ogrLayer.name() = "vector-data";
ogrLayer.featureSource() = featureData;
map->addLayer(new osgEarth::Features::FeatureSourceLayer(ogrLayer));
 
/*******↑featureData添加到FeatureSourceLayer,*****↓符号化*******/
 
3.初始化线样式
// 对ls alt render 进行设置
Style style;
osgEarth::Symbology::LineSymbol* ls = style.getOrCreateSymbol<LineSymbol>();
osgEarth::Symbology::AltitudeSymbol* alt = style.getOrCreate<AltitudeSymbol>();
osgEarth::Symbology::RenderSymbol* render = style.getOrCreate<RenderSymbol>();
 
 
4.光栅化或矢量化，二选一
4.1光栅化
osgEarth::Drivers::AGGLiteOptions rasterOptions;
rasterOptions.featureOptions() = featureData;
rasterOptions.styles()->addStyle( style );
map->addLayer(new ImageLayer("My Features", rasterOptions) );
 
4.2矢量化
osgEarth::Features::FeatureModelLayerOptions fml;
fml.styles()->addStyle(style);
map->addLayer(new FeatureModelLayer(fml));
 
5.如果需要加入label样式，以矢量化为前提
osgEarth::Symbology::Style labelStyle;
osgEarth::Symbology::TextSymbol* text = labelStyle.getOrCreateSymbol<TextSymbol>();
FeatureModelLayerOptions fml;
fml.styles()->addStyle( labelStyle );
map->addLayer(new FeatureModelLayer(fml));

加载模式

// rasterize 光栅化，不输入时，会显示名称
// mem参数输入，加载矩形，否则加载world.shp文件。shp文件路径一定要写全路径，否则无法加载。
// labels 可以不用填写。
// clamp 和 drape 任选其一。
 
// 采用clamp方式绘制
osgearth_featuresd.exe --rasterize --mem --labels --clamp
 
// 采用drape方式绘制
osgearth_featuresd.exe --rasterize --mem --labels --drape
 
// 还有多种组合方式
osgearth_featuresd.exe --labels --drape