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MFC显示OSGB模型

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  1. 概览
  2. OSG读取OSGB模型并显示
  3. MFC视图显示OSGB模型

概览

OSG提供了一个浏览三维模型的视图osgViewer::Viewer，将.osg或.osgb文件通过osgDB::readNodeFile()读进来后用osgViewer::Viewer::setSceneData()添加到视图中，接着调用osgViewer::Viewer::run()即可开一个新的窗口显示。

MFC提供了C++软件程序框架，可以显示单个或多个窗口、对话框，并提供了文件、路径选择的接口，可以用来开发基础的OSGB浏览软件。将MFC视图的窗口句柄传递给osgViewer，并设置一些运行过程的控制，即可实现在MFC中使用OSG自带的视图显示OSGB模型。

OSG读取OSGB模型并显示

以下代码实现的功能：拖动一个.osgb文件到exe文件上，即可打开一个全屏的视图显示OSGB模型。

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#include<osgViewer/Viewer>
#include<osgDB/ReadFile>

int main(int argc, char* argv[])
{
	if (argc != 2) return 1;
	const std::string indexFilePath = argv[1];
	std::cout << indexFilePath << std::endl;
	const std::string dirPath = indexFilePath.substr(0, indexFilePath.find_last_of('\\'));

	auto opts = new osgDB::Options();
	opts->setDatabasePath(dirPath);
	const osg::ref_ptr<osg::Node> node = osgDB::readNodeFile(indexFilePath, opts);

	// 关闭光照使均匀
	node->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);

	// 修改子节点路径为绝对
	osg::Group* group = dynamic_cast<osg::Group*>(node.get());
	for (size_t i = 0; i < group->getNumChildren(); i++)
	{
		osg::PagedLOD* plod = dynamic_cast<osg::PagedLOD*>(group->getChild(i));
		plod->setDatabasePath(dirPath + plod->getDatabasePath());
		std::cout << dirPath + plod->getDatabasePath() << std::endl;
	}

	// 创建视窗显示
	osgViewer::Viewer viewer;
	viewer.setSceneData(node);
	viewer.setUpViewOnSingleScreen(1);
	return viewer.run();
}

MFC视图显示OSGB模型

首先新建一个类：

COsgbViewer.h

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#pragma once
#include <string>
#include <osgViewer/Viewer>

class COsgbViewer
{
public:
	COsgbViewer(HWND hWnd);
	~COsgbViewer();

	void InitOsgb(std::string filepath);

	osg::ref_ptr<osgViewer::Viewer> GetViewer() const;

	static void Render(void*);

private:
	HWND m_hWnd;
	osg::ref_ptr<osgViewer::Viewer> m_lpViewer;
};

COsgbViewer.cpp

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#include "COsgbViewer.h"
#include <osgViewer/api/Win32/GraphicsWindowWin32>
#include <osgDB/ReadFile>
#include <osgGA/TrackballManipulator>

COsgbViewer::COsgbViewer(HWND hWnd)
{
	this->m_hWnd = hWnd;
}

COsgbViewer::~COsgbViewer()
{
}

void COsgbViewer::InitOsgb(std::string filepath)
{
	std::replace(filepath.begin(), filepath.end(), '/', '\\');
	const std::string dirPath = filepath.substr(0, filepath.find_last_of('\\'));
	auto opts = new osgDB::Options();
	opts->setDatabasePath(dirPath);
	const osg::ref_ptr<osg::Node> node = osgDB::readNodeFile(filepath, opts);

	if (node == nullptr)
		return;

	// 关闭光照使均匀
	node->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);

	// 修改子节点路径为绝对
	osg::Group* group = dynamic_cast<osg::Group*>(node.get());
	for (size_t i = 0; i < group->getNumChildren(); i++)
	{
		osg::PagedLOD* plod = dynamic_cast<osg::PagedLOD*>(group->getChild(i));
		plod->setDatabasePath(dirPath + plod->getDatabasePath());
	}

	// 构建视窗
	RECT m_rect;
	::GetWindowRect(m_hWnd, &m_rect);

	// 通过traits传递窗口句柄
	osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits();
	osg::ref_ptr<osg::Referenced> windata = new osgViewer::GraphicsWindowWin32::WindowData(m_hWnd);

	traits->x = 0;
	traits->y = 0;
	traits->width = m_rect.right - m_rect.left;
	traits->height = m_rect.bottom - m_rect.top;
	traits->windowDecoration = true;
	traits->doubleBuffer = true;
	traits->overrideRedirect = false;
	traits->sharedContext = 0;
	traits->setInheritedWindowPixelFormat = true;
	traits->inheritedWindowData = windata;

	// 创建视窗osgViewer，并修改其句柄为MFC窗口
	m_lpViewer = new osgViewer::Viewer;
	osg::ref_ptr<osg::Camera> camera = m_lpViewer->getCamera();
	camera->setGraphicsContext(osg::GraphicsContext::createGraphicsContext(traits));
	camera->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));
	m_lpViewer->setCamera(camera);

	// 添加相机交互
	m_lpViewer->setCameraManipulator(new osgGA::TrackballManipulator);

	// 设置三维数据并显示
	m_lpViewer->setSceneData(node);
	m_lpViewer->realize();
	m_lpViewer->getCamera()->setComputeNearFarMode(osg::CullSettings::COMPUTE_NEAR_FAR_USING_PRIMITIVES);
}

osg::ref_ptr<osgViewer::Viewer> COsgbViewer::GetViewer() const
{
	return this->m_lpViewer;
}

void COsgbViewer::Render(void* ptr)
{
	const auto self = (COsgbViewer*)ptr;
	const auto viewer = self->GetViewer();
	while (!viewer->done())
	{
		viewer->frame();
	}
	_endthread();
}

接着在MFC的view类（继承自CView，命名为：CBigViewerView）中添加成员变量：

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private:
	COsgbViewer* m_lpOsgbViewer;

接着重载虚函数OnInitialUpdate和三个消息响应函数：

OnInitialUpdate：加载模型文件后开一个线程处理渲染过程，在这里提供文件路径

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void CBigViewerView::OnInitialUpdate()
{
	CView::OnInitialUpdate();

	// TODO: 在此添加专用代码和/或调用基类
	m_lpOsgbViewer->InitOsgb("D:\\codes\\C++\\reconstruct-engine\\DJI_202207281718_006_1area04125cmc_1-2\\model-osgb\\Model.osgb");
	_beginthread(&COsgbViewer::Render, 0, m_lpOsgbViewer);
}

OnCreate：视图类创建时先进行初始化，将窗口句柄给到自定义的viewer类中

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int CBigViewerView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
	if (CView::OnCreate(lpCreateStruct) == -1)
		return -1;

	// TODO:  在此添加您专用的创建代码
	m_lpOsgbViewer = new COsgbViewer(m_hWnd);

	return 0;
}

OnEraseBkgnd：好像没啥用？无论是单文档还是多文档都无法触发

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BOOL CBigViewerView::OnEraseBkgnd(CDC* pDC)
{
	// TODO: 在此添加消息处理程序代码和/或调用默认值
	if (m_lpOsgbViewer) return FALSE;

	return CView::OnEraseBkgnd(pDC);
}

OnDestroy：退出时注销OSG视图类

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void CBigViewerView::OnDestroy()
{
	CView::OnDestroy();

	// TODO: 在此处添加消息处理程序代码
	if (m_lpOsgbViewer)
	{
		delete m_lpOsgbViewer;
	}
}