使用OSG创建一个简单的地形

#include <iostream>
#include <Windows.h>

#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#include <osg/Texture2D>
#include <osg/ShapeDrawable>
#include <gdal_priv.h>

using namespace std;

using namespace osg;
using namespace osgViewer;

//实现函数:从高程图创建地形
osg::Node* createHeightField(std::string heightFile, std::string texFile)
{
	//读取高度文件
	GDALAllRegister();          //GDAL所有操作都需要先注册格式
	CPLSetConfigOption("GDAL_FILENAME_IS_UTF8", "NO");  //支持中文路径
	GDALDataset* img = (GDALDataset *)GDALOpen(heightFile.c_str(), GA_ReadOnly);
	if (!img)
	{
		return nullptr;
	}

	//读取基本参数
	int imgWidth = img->GetRasterXSize();   //图像宽度
	int imgHeight = img->GetRasterYSize();  //图像高度
	int bandNum = img->GetRasterCount();    //波段数
	int depth = GDALGetDataTypeSize(img->GetRasterBand(1)->GetRasterDataType()) / 8;    //图像深度

	//获取地理坐标信息
	double padfTransform[6];
	if (img->GetGeoTransform(padfTransform) == CE_Failure)
	{
		return nullptr;
	}
	double startX = padfTransform[0] + 0.5 * padfTransform[1];			//左上角点坐标X
	double dX = padfTransform[1];			//X方向的分辨率		
	double startY = padfTransform[3] + padfTransform[5] * imgHeight - 0.5 * padfTransform[5];			//左下角点坐标Y
	double dY = -padfTransform[5];			//Y方向的分辨率

	//申请buf
	int bufWidth = imgWidth;
	int bufHeight = imgHeight;
	size_t imgBufNum = (size_t)bufWidth * bufHeight * bandNum;
	float *imgBuf = new float[imgBufNum];

	//读取
	size_t imgBufOffset = (size_t)bufWidth * (bufHeight - 1) * bandNum;
	img->RasterIO(GF_Read, 0, 0, bufWidth, bufHeight, imgBuf + imgBufOffset, bufWidth, bufHeight,
		GDT_Float32, bandNum, nullptr, bandNum*depth, -bufWidth*bandNum*depth, depth);

	//定义并设置高度文件
	osg::ref_ptr<osg::HeightField> heightField = new osg::HeightField();
	heightField->allocate(imgWidth, imgHeight);			//申请空间
	heightField->setOrigin(osg::Vec3(startX, startY, 0));			//起始位置	
	heightField->setXInterval(dX);			//间距X
	heightField->setYInterval(dY);			//间距Y
	heightField->setSkirtHeight(1.0f);

	//填充高度值
	for (int r = 0; r < imgHeight; r++)
	{
		for (int c = 0; c < imgWidth; c++)
		{
			size_t m = (size_t)r * imgWidth + c;
			heightField->setHeight(c, r, imgBuf[m]);
		}
	}

	//释放
	delete[] imgBuf;
	imgBuf = nullptr;

	//节点
	osg::Geode* geode = new osg::Geode();
	osg::ref_ptr<osg::ShapeDrawable> heightShape = new osg::ShapeDrawable(heightField.get());
	geode->addDrawable(heightShape);

	//设置纹理
	osg::ref_ptr<osg::Image> texImage = osgDB::readImageFile(texFile);
	osg::ref_ptr<osg::Texture2D> tex = new osg::Texture2D;
	tex->setImage(texImage);
	tex->setDataVariance(osg::Object::DYNAMIC);

	//渲染状态
	osg::ref_ptr<osg::StateSet> stateset = new osg::StateSet();
	stateset->setTextureAttributeAndModes(0, tex.get(), osg::StateAttribute::ON);
	geode->setStateSet(stateset.get());

	return geode;
}

int main()
{	
	osgViewer::Viewer viewer;
	osg::ref_ptr<osg::Group> group = new osg::Group;

	std::string heightFile = "D:\\Data\\dst.tif";
	std::string texFile = "D:\\Data\\dom3_Level_19.jpg";
	group->addChild(createHeightField(heightFile, texFile));

	viewer.setSceneData(group);
	viewer.setUpViewInWindow(100, 100, 800, 600);
	return viewer.run();
}