项目实战：Qt+OSG教育学科工具之地理三维星球

若该文为原创文章，未经允许不得转载
原博主博客地址：https://blog.csdn.net/qq21497936
原博主博客导航：https://blog.csdn.net/qq21497936/article/details/102478062
本文章博客地址：https://blog.csdn.net/qq21497936/article/details/105372492
各位读者，知识无穷而人力有穷，要么改需求，要么找专业人士，要么自己研究

红胖子(红模仿)的博文大全：开发技术集合（包含Qt实用技术、树莓派、三维、OpenCV、OpenGL、ffmpeg、OSG、单片机、软硬结合等等）持续更新中...（点击传送门）

Qt开发专栏：项目实战（点击传送门）

OSG开发专栏（点击传送门）

需求

使用Qt开发内嵌的三维地理学科工具。

原理

使用Qt+Osg三维研发，依托Qt内嵌OSG。

相关博客

《OSG三维开发专栏》：循序渐进学习OSG

《OSG开发笔记（一）：OSG介绍、编译》：OSG介绍与编译

《OSG开发笔记（四）：OSG不使用osgQt重写类嵌入Qt应用程序》：OSG源码嵌入Qt

《OSG开发笔记（十）：OSG模型的变换之平移、旋转和缩放》：对于模型结点的基本操作

《OSG开发笔记（十四）：OSG交互》：按键消息和鼠标消息的交互

《OSG开发笔记（十五）：OSG光照》：光影的学习，产生立体感

《OSG开发笔记（十八）：OSG鼠标拾取pick、拽托球体以及多光源》：pick拾取三维物体交互

《OSG开发笔记（二十一）：OSG使用HUD绘制图形以及纹理混合模式》：hud绘制背景和前景

《OSG开发笔记（二十三）：Qt使用QOpenGLWidget渲染OSG和地球仪》：基础版本的地球仪开发关键

（以上是支撑该需求的三维技术博客）

Demo v3.1.0

相比于v2.0.0版本：修复了星球纹理贴图存在缝隙的问题；修复了缩放无限制的bug；对球体、贴图、2d/3d切换、缩放、旋转增加了序列化接口(demo为启动应用后恢复之前关闭的状态)。

下载地址

Demo v3.1.0运行包下载地址：https://download.csdn.net/download/qq21497936/12542665

QQ群：1047134658（点击“文件”搜索“教育学科工具”，群内与博文同步更新）

Demo v2.0.0

相比于v1.0.0版本，增加了地球以外的八大行星，对布局进行了调整，适配了多种分辨率，并且优化了部分代码；

下载地址

Demo v2.0.0运行包下载地址：https://download.csdn.net/download/qq21497936/12312105

QQ群：1047134658（点击“文件”搜索“教育学科工具”，群内与博文同步更新所有可开源的源码模板）

Demo v1.0.0

完成地理星球中地球的研发，包括基本操作、鼠标pick旋转、缩放等，包含海洋分布、人口分布、气候分布、海平线等等功能；

下载地址

Demo v1.0.0运行包下载地址：https://download.csdn.net/download/qq21497936/11489564

QQ群：1047134658（点击“文件”搜索“教育学科工具”，群内与博文同步更新所有可开源的源码模板）

关键代码

获取背景Hud结点（传入文件）

osg::ref_ptr<osg::Node> OsgStarWidget::getBackgroundNode(QString imageFile)
{
    osg::ref_ptr<osg::Group> pGroup = new osg::Group();
    osg::ref_ptr<osg::Camera> pCamera = 0;
    osg::ref_ptr<osg::Geode> pGeode = 0;
    // 创建背景相机
    {
        // 步骤一：创建相机
        pCamera = new osg::Camera();
        // 步骤二：设置矩阵  显示得界面边坐标      左    右  下    上
        pCamera->setProjectionMatrixAsOrtho2D(0, 1920, 0, 1080);
        // 步骤三：设置视图矩阵
        pCamera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
        // 步骤四：不受父类矩阵影响
        pCamera->setViewMatrix(osg::Matrix::identity());
        // 步骤五：清除深度缓存
        pCamera->setClearMask(GL_DEPTH_BUFFER_BIT);
        // 步骤六：设置为不接受事件，让其得不到焦点
        pCamera->setAllowEventFocus(false);
        // 步骤七：设置渲染顺序
        pCamera->setRenderOrder(osg::Camera::NESTED_RENDER);    // 显示为背景HUD
        // 步骤八：关闭光照，通过osg::StateSet设置
        pGeode = new osg::Geode();
        osg::ref_ptr<osg::StateSet> pStateSet = pGeode->getOrCreateStateSet();
        pStateSet->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
        // 步骤九：关闭深度测试
        pStateSet->setMode(GL_DEPTH_TEST, osg::StateAttribute::OFF);
    }
    // 创建背景图形图片
    {
        // 步骤一：创建几何信息体
        osg::ref_ptr<osg::Geometry> pGeometry = new osg::Geometry;
        // 步骤二：绑定顶点
        osg::ref_ptr<osg::Vec3Array> pVec3Array = new osg::Vec3Array;
        pGeometry->setVertexArray(pVec3Array.get());
        // 步骤三：设置顶点(屏幕坐标)
        pVec3Array->push_back(osg::Vec3(   0,    0, 0));
        pVec3Array->push_back(osg::Vec3(1920,    0, 0));
        pVec3Array->push_back(osg::Vec3(1920, 1080, 0));
        pVec3Array->push_back(osg::Vec3(   0, 1080, 0));
        // 步骤四：读取图片(纹理图片)
        osg::ref_ptr<osg::Image> pImage = new osg::Image;
        pImage = osgDB::readImageFile(imageFile.toStdString());
        if(!pImage || !pImage->valid())
        {
            LOG_WARN(QString("Failed to load image file: %1").arg(imageFile));
            return 0;
        }
        // 步骤五：创建纹理
        osg::ref_ptr<osg::Texture2D> pTexture2D = new osg::Texture2D;
        pTexture2D->setImage(pImage);
        pTexture2D->setUnRefImageDataAfterApply(true);
        // 步骤六：绑定纹理坐标
        osg::ref_ptr<osg::Vec2Array> pVec2Array = new osg::Vec2Array;
        pGeometry->setTexCoordArray(0, pVec2Array.get());
        // 步骤七：设置纹理坐标
        pVec2Array->push_back(osg::Vec2(0.0, 0.0));
        pVec2Array->push_back(osg::Vec2(1.0, 0.0));
        pVec2Array->push_back(osg::Vec2(1.0, 1.0));
        pVec2Array->push_back(osg::Vec2(0.0, 1.0));
        // 步骤八：关联纹理状态
        osg::ref_ptr<osg::StateSet> pStateSet = pGeometry->getOrCreateStateSet();
        pStateSet->setTextureAttributeAndModes(0, pTexture2D.get(), osg::StateAttribute::ON);
        // 步骤九：绑定法线
        osg::ref_ptr<osg::Vec3Array> pVec3ArrayNormal = new osg::Vec3Array;
        pGeometry->setNormalArray(pVec3ArrayNormal.get());
        // 步骤十：设置法线方式
        pGeometry->setNormalBinding(osg::Geometry::BIND_OVERALL);
        // 步骤十一：设置法线方向
        pVec3ArrayNormal->push_back(osg::Vec3f(0.0, 1.0, 0.0));
        // 步骤十二：绘制四个顶点的图形
        pGeometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS, 0, 4));
        // 步骤十三：将图形添加进几何节点
        pGeode->addDrawable(pGeometry.get());
    }
    pCamera->addChild(pGeode);
    pGroup->addChild(pCamera);
    return pGroup;
}

更换地球纹理

void OsgStarWidget::change3DImage(QString imageFile)
{
    // 步骤一：读取图片(纹理图片)
    osg::ref_ptr<osg::Image> pImage = 0;
    pImage = osgDB::readImageFile(imageFile.toStdString());
    if(!pImage || !pImage->valid())
    {
        LOG_WARN(QString("Failed to load image file: %1").arg(imageFile));
        return;
    }
    // 步骤二：创建纹理
    osg::ref_ptr<osg::Texture2D> pTexture2D = new osg::Texture2D;
    pTexture2D->setImage(pImage);
    pTexture2D->setUnRefImageDataAfterApply(true);
    // 步骤三：球体体渲染纹理
    osg::ref_ptr<osg::StateSet> pStateSet = _pGeode->getOrCreateStateSet();
    pStateSet->setTextureAttribute(0, pTexture2D.get());
    pStateSet->setTextureMode(0, GL_TEXTURE_2D, osg::StateAttribute::ON);
    _pGeode->setStateSet(pStateSet);

}

拾取pick、缩放

MyUserPickEventHandler.h

#ifndef MYUSERPICKEVENTHANDLER_H
#define MYUSERPICKEVENTHANDLER_H

#include <osg/Node>
#include <osgViewer/Viewer>

class MyUserPickEventHandler : public osgGA::GUIEventHandler
{

public:
    MyUserPickEventHandler();

public:
    osg::ref_ptr<osg::MatrixTransform> getMatrixTransform() const;
    void setMatrixTransform(const osg::ref_ptr<osg::MatrixTransform> &pMatrixTransform);
    float getRadius() const;
    void setRadius(float radius);
    float getMinScale() const;
    void setMinScale(float minScale);
    float getMaxScale() const;
    void setMaxScale(float maxScale);
    float getZoomInStep() const;
    void setZoomInStep(float zoomInStep);
    float getZoomOutStep() const;
    void setZoomOutStep(float zoomOutStep);

public:
    /** Handle event. Override the handle(..) method in your event handlers to respond to events. */
//    virtual bool handle(osgGA::Event* event, osg::Object* pObject, osg::NodeVisitor* pNodeVisitor);

    /** Handle events, return true if handled, false otherwise. */
//    virtual bool handle(const osgGA::GUIEventAdapter& guiEventAdapter, osgGA::GUIActionAdapter& guiActionAdapter, osg::Object* pObject, osg::NodeVisitor* pNodeVisitor);

    /** Deprecated, Handle events, return true if handled, false otherwise. */
    virtual bool handle(const osgGA::GUIEventAdapter& guiEventAdapter, osgGA::GUIActionAdapter& guiActionAdapter);

protected:
    bool pick(const double x, const double y, osgViewer::Viewer *pViewer, osg::Vec3dArray *pVec3dArrayOut);
    bool pick(const double x, const double y, osgViewer::Viewer *pViewer, osg::Node *pNode, osg::Vec3dArray *pVec3dArrayOut);
    osg::Vec3d screen2Word(osg::Vec3d screenVec3d, osgViewer::Viewer *pViewer);

private:
    bool _pickEarth;
    osg::Vec3d _originVec3d;
    osg::Vec3d _lastVec3d;
    float _radius;
    float _maxScale;
    float _minScale;
    float _zoomInStep;
    float _zoomOutStep;
    osg::ref_ptr<osg::MatrixTransform> _pMatrixTransform;
};

#endif // MYUSEREVENTHANDLER_H

MyUserPickEventHandler.cpp

#include "MyUserPickEventHandler.h"
#include "define.h"
#include "osg/MatrixTransform"
#include <QtMath>
#include "MyMath.h"

MyUserPickEventHandler::MyUserPickEventHandler()
    : osgGA::GUIEventHandler(),
      _pickEarth(false)
{

}

osg::ref_ptr<osg::MatrixTransform> MyUserPickEventHandler::getMatrixTransform() const
{
    return _pMatrixTransform;
}

void MyUserPickEventHandler::setMatrixTransform(const osg::ref_ptr<osg::MatrixTransform> &pMatrixTransform)
{
    _pMatrixTransform = pMatrixTransform;
}

float MyUserPickEventHandler::getRadius() const
{
    return _radius;
}

void MyUserPickEventHandler::setRadius(float radius)
{
    _radius = radius;
}

float MyUserPickEventHandler::getMaxScale() const
{
    return _maxScale;
}

void MyUserPickEventHandler::setMaxScale(float maxScale)
{
    _maxScale = maxScale;
}

float MyUserPickEventHandler::getMinScale() const
{
    return _minScale;
}

void MyUserPickEventHandler::setMinScale(float minScale)
{
    _minScale = minScale;
}

float MyUserPickEventHandler::getZoomInStep() const
{
    return _zoomInStep;
}

void MyUserPickEventHandler::setZoomInStep(float zoomInStep)
{
    _zoomInStep = zoomInStep;
}

//bool MyUserEventHandler::handle(osgGA::Event *event, osg::Object *object, osg::NodeVisitor *pNodeVisitor)
//{
//    LOG_DEBUG("");
//    return false;
//}

//bool MyUserEventHandler::handle(const osgGA::GUIEventAdapter &guiEventAdapter, osgGA::GUIActionAdapter &guiActionAdapter, osg::Object *pObject, osg::NodeVisitor *pNodeVisitor)
//{
//    LOG_DEBUG("");
//    return true;
//}

bool MyUserPickEventHandler::handle(const osgGA::GUIEventAdapter
                                &guiEventAdapter, osgGA::GUIActionAdapter &guiActionAdapter)
{
    switch (guiEventAdapter.getEventType())
    {
        case osgGA::GUIEventAdapter::EventType::SCROLL:
        case osgGA::GUIEventAdapter::EventType::PUSH:
        case osgGA::GUIEventAdapter::EventType::RELEASE:
        case osgGA::GUIEventAdapter::EventType::DRAG:
            break;
        default:
            return true;
            break;
    }
    bool flag = false;
    if(_pMatrixTransform.get() == 0)
    {
        LOG_INFO("Fialed to handle, because it's not set the node of transform!!!");
        return true;
    }
    // 使用智能指针就挂，原因未知
//    osg::ref_ptr<osgViewer::Viewer> pViewer = dynamic_cast<osgViewer::Viewer*>(&guiActionAdapter);
    osgViewer::Viewer *pViewer = dynamic_cast<osgViewer::Viewer*>(&guiActionAdapter);
    if(pViewer == 0)
    {
        LOG_WARN("Fialed to get viewer!");
        return true;
    }
    osg::Matrix matrix = _pMatrixTransform->getMatrix();
    osg::Vec3d vec3d;
    osg::ref_ptr<osg::Vec3dArray> pVec3dArray = new osg::Vec3dArray();
    qreal offsetAngle;
    float nowRadius = qSqrt(_pMatrixTransform->getBound().radius2() / 3.0);
    switch (guiEventAdapter.getEventType())
    {
    case osgGA::GUIEventAdapter::EventType::SCROLL:
        switch (guiEventAdapter.getScrollingMotion())
        {
            case osgGA::GUIEventAdapter::SCROLL_UP:     // 鼠标滚轮向上放大
                if(nowRadius / _radius >= _maxScale)
                {
                    break;
                }
                matrix *= osg::Matrix::scale(_zoomInStep, _zoomInStep, _zoomInStep);
                _pMatrixTransform->setMatrix(matrix);
                flag = true;
                break;
            case osgGA::GUIEventAdapter::SCROLL_DOWN:   // 鼠标滚轮向下缩小
                if(nowRadius / _radius <= _minScale)
                {
                    break;
                }
                matrix *= osg::Matrix::scale(_zoomOutStep, _zoomOutStep, _zoomOutStep);
                _pMatrixTransform->setMatrix(matrix);
                flag = true;
                break;
            default:
                break;
        }
        break;
    case osgGA::GUIEventAdapter::EventType::PUSH:
        switch (guiEventAdapter.getButton())
        {
        case osgGA::GUIEventAdapter::LEFT_MOUSE_BUTTON:
            if(pick(guiEventAdapter.getX(), guiEventAdapter.getY(), pViewer, _pMatrixTransform, pVec3dArray.get()))
            {
                // 拾取到物体
                _pickEarth = true;
                _lastVec3d = pVec3dArray->at(0);
            }else{
                _pickEarth = false;
            }
            break;
        default:
            break;
        }
        break;
    case osgGA::GUIEventAdapter::EventType::DRAG:
        if(pick(guiEventAdapter.getX(), guiEventAdapter.getY(), pViewer, _pMatrixTransform, pVec3dArray.get()))
        {
            if(_pickEarth == false)
            {
                // 拾取到物体
                _pickEarth = true;
                _lastVec3d = pVec3dArray->at(0);
                break;
            }
            // 相交点
            vec3d = pVec3dArray->at(0);
            // 计算x轴方向角度
            offsetAngle = MyMath::lineAngleRakeRatio(QPoint(0,0), QPointF(vec3d.y(), vec3d.z()))
                          -MyMath::lineAngleRakeRatio(QPoint(0,0), QPointF(_lastVec3d.y(), _lastVec3d.z()));
            matrix *= osg::Matrix::rotate(osg::DegreesToRadians(-offsetAngle), 1, 0, 0);
            // 计算z轴方向角度
            offsetAngle = MyMath::lineAngleRakeRatio(QPoint(0,0), QPointF(vec3d.y(), vec3d.x()))
                          -MyMath::lineAngleRakeRatio(QPoint(0,0), QPointF(_lastVec3d.y(), _lastVec3d.x()));
            matrix *= osg::Matrix::rotate(osg::DegreesToRadians(offsetAngle), 0, 0, 1);
            _pMatrixTransform->setMatrix(matrix);
            _lastVec3d = vec3d;
        }else{
            _pickEarth = false;
        }
        break;
    case osgGA::GUIEventAdapter::EventType::RELEASE:
        _pickEarth = false;
        break;

    default:
        break;
    }
    return true;
}

bool MyUserPickEventHandler::pick(const double x, const double y, osgViewer::Viewer *pViewer, osg::Vec3dArray *pVec3dArrayOut)
{
    bool ret = false;
    // 判断场景
    if(!pViewer->getSceneData())
    {
        return false;
    }
    // 判断是否拾取到物体
    osgUtil::LineSegmentIntersector::Intersections intersections;
    if(pViewer->computeIntersections(x, y, intersections))
    {
        for(auto iter = intersections.begin();
            iter != intersections.end();
            iter++)
        {
            pVec3dArrayOut->push_back(iter->getWorldIntersectPoint());
            ret = true;
        }
    }
    return ret;
}

bool MyUserPickEventHandler::pick(const double x, const double y, osgViewer::Viewer *pViewer, osg::Node *pNode, osg::Vec3dArray *pVec3dArrayOut)
{
    bool ret = false;
    // 判断场景
    if(!pViewer->getSceneData())
    {
        return false;
    }
    // 判断是否拾取到物体
    osgUtil::LineSegmentIntersector::Intersections intersections;
    if(pViewer->computeIntersections(x, y, intersections))
    {
        for(auto iter = intersections.begin();
            iter != intersections.end();
            iter++)
        {
            for(int index = 0; index < iter->nodePath.size();  index++)
            {
                if(iter->nodePath.at(index)->asNode() == pNode)
                {
                    pVec3dArrayOut->push_back(iter->getWorldIntersectPoint());
                    ret = true;
                    break;
                }
            }
            break;
        }
    }
    return ret;
}

osg::Vec3d MyUserPickEventHandler::screen2Word(osg::Vec3d screenVec3d, osgViewer::Viewer *pViewer)
{
    osg::ref_ptr<osg::Camera> pCamera = pViewer->getCamera();
    osg::Matrix matrix = pCamera->getViewMatrix() *
                         pCamera->getProjectionMatrix() *
                         pCamera->getViewport()->computeWindowMatrix();
    osg::Matrix intertMatrix = osg::Matrix::inverse(matrix);
    osg::Vec3d worldVec3d = screenVec3d * intertMatrix;
    return worldVec3d;
}

float MyUserPickEventHandler::getZoomOutStep() const
{
    return _zoomOutStep;
}

void MyUserPickEventHandler::setZoomOutStep(float zoomOutStep)
{
    _zoomOutStep = zoomOutStep;
}

原博主博客地址：https://blog.csdn.net/qq21497936
原博主博客导航：https://blog.csdn.net/qq21497936/article/details/102478062
本文章博客地址：https://blog.csdn.net/qq21497936/article/details/105372492