OSG 单视图 hudCamera 实现导航拖拽器

上篇博客是用多视图实现了一个类似于Hud导航的效果，并不是真正意义上的基于单视图的Hud导航器。因此，这篇博客是要说怎样实现一个基于单视图的导航器，这花费了不少时间。转载时，请注明出处，谢谢。单视图实现导航器的核心就是保证漫游器旋转时，我们的Hud相机要能够准确的进行类似旋转。以下是我的代码部分，这次没有重写我们的TrackballManipulator类。

#ifndef __CHUD_PICK_HANDLER_H_#define __CHUD_PICK_HANDLER_H_#include <iostream>#include <osgViewer/Viewer>#include <osgGA/TrackballManipulator>#include <osg/Array>#include <osg/Geode>// 主要是点击导航器时，实现特定面的旋转class CHUDPickHandler : public osgGA::GUIEventHandler{public:    CHUDPickHandler() : m_pTrackballManipulator(new osgGA::TrackballManipulator) {}    // 创建场景构建    void createSceneNode(osg::ref_ptr<osgViewer::Viewer> _viewer, osg::ref_ptr<osg::Group> _root);    // 设置视口位置    void setHudViewPositionAndCubeWidth(double _x, double _y, double _width, double _height, float _cubeWidth = 80.0f);private:    virtual bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa,        osg::Object*, osg::NodeVisitor*);    // 处理立方体被点击的面    virtual void pick(osgViewer::Viewer* view, const osgGA::GUIEventAdapter& ea);    // 初始化导航立方体的顶点信息和纹理信息    void initVertexAndNormalData();    // 利用顶点信息和纹理信息创建一个导航立方体    osg::Geode* createCustomCubeGeometry();private:    enum CUBE_FACE    {        CUBE_FRONT = 0,        CUBE_BACK,        CUBE_UP,        CUBE_DOWN,        CUBE_LEFT,        CUBE_RIGHT    };    // 立方体的顶点信息    osg::ref_ptr<osg::Vec3Array>                    m_vec3VerCoords;    // 立方体每个面的纹理信息    osg::ref_ptr<osg::Vec2Array>                    m_vec2TexCoords;    // 每个面所需要的顶点序号 如2表示m_vec3VerCoords[2] 这个顶点    osg::ref_ptr<osg::Vec4iArray>                   m_vec4FaceVertexs;    // 追踪主视图漫游器    osg::ref_ptr<osgGA::TrackballManipulator>       m_pTrackballManipulator;    // 我们的Hud相机，便于实时旋转操作    osg::ref_ptr<osg::Camera>                       m_pHudCamera;    osg::ref_ptr<osg::Viewport>                     m_pViewport;    float                                           m_cubeWidth;};#endif //__CHUD_PICK_HANDLER_H_

上面就是我的CHUDPickHandler.h定义，没什么好说的了。下面是我的实现:

#include "CHUDEventHandler.h"#include <osg/Texture2D>#include <osgDB/ReadFile>#include <osgViewer/Viewer>#include <osg/BlendColor>#include <osg/BlendFunc>// 处理输入事件bool CHUDPickHandler::handle(const osgGA::GUIEventAdapter& ea,     osgGA::GUIActionAdapter& aa, osg::Object* obj, osg::NodeVisitor* nv){    osgViewer::Viewer* viewer = dynamic_cast<osgViewer::Viewer*>(&aa);    if (viewer == nullptr)    {        return false;    }    switch (ea.getEventType())    {    case(osgGA::GUIEventAdapter::PUSH) :    {        // Hud视图点击时进行旋转        pick(viewer, ea);        return false;    }    case(osgGA::GUIEventAdapter::FRAME):     {        // 保证HUD视图可以随主视图旋转        if (m_pTrackballManipulator && m_pHudCamera)        {            osg::Vec3d eye, up, center;            m_pTrackballManipulator->getTransformation(eye, center, up);            osg::Vec3 delt = center - eye;            delt.normalize();            /* 整个实现逻辑的核心            保证HUD相机方向和漫游器方向相同 */            m_pHudCamera->setViewMatrixAsLookAt(                delt * (-1000.0) * this->m_cubeWidth,                osg::Vec3(0, 0, 0),                up);        }        return false;    }    default:        return false;    }}void CHUDPickHandler::pick(osgViewer::Viewer* viewer, const osgGA::GUIEventAdapter& ea){    // 检测碰撞    osg::ref_ptr<osg::Drawable> drawable = nullptr;    osgUtil::LineSegmentIntersector::Intersections intersections;    if (viewer->computeIntersections(ea, intersections))    {        // 只取可绘制的几何节点 因为我们检测的是几何形碰撞        osgUtil::LineSegmentIntersector::Intersection intersection = *intersections.begin();        drawable = intersection.drawable;    }    if (drawable)    {        const std::string facename = drawable->getName();        std::cout << "facename is " << facename << std::endl;        if (facename == "") { return; }        int index = ::atoi(facename.c_str());        double zerodegree = 0.0f;        osg::Vec3f v3;        // 这里我们操作漫游器进行旋转 因为帧循环时我们的Hud相机可以立刻跟随漫游器进行旋转        switch (index)        {        case CUBE_FRONT: // 前        {            m_pTrackballManipulator->setRotation(osg::Quat(                osg::inDegrees(90.0f), osg::Vec3(1.0f, zerodegree, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, 1.0f, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, zerodegree, 1.0f)                ));        }            break;        case CUBE_BACK: // 后        {            m_pTrackballManipulator->setRotation(osg::Quat(                osg::inDegrees(90.0), osg::Vec3(1.0f, zerodegree, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, 1.0f, zerodegree),                osg::inDegrees(180.0f), osg::Vec3(zerodegree, zerodegree, 1.0f)                ));        }            break;        case CUBE_UP: // 上        {            m_pTrackballManipulator->setRotation(osg::Quat(                osg::inDegrees(zerodegree), osg::Vec3(1.0f, zerodegree, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, 1.0f, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, zerodegree, 1.0f)                ));        }            break;        case CUBE_DOWN: // 下        {            m_pTrackballManipulator->setRotation(osg::Quat(                osg::inDegrees(180.0), osg::Vec3(1.0f, zerodegree, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, 1.0f, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, zerodegree, 1.0f)                ));        }            break;        case CUBE_LEFT: // 左        {            m_pTrackballManipulator->setRotation(osg::Quat(                osg::inDegrees(90.0f), osg::Vec3(1.0f, zerodegree, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, 1.0f, zerodegree),                osg::inDegrees(270.0f), osg::Vec3(zerodegree, zerodegree, 1.0f)                ));        }            break;        case CUBE_RIGHT: // 右        {            m_pTrackballManipulator->setRotation(osg::Quat(                osg::inDegrees(90.0), osg::Vec3(1.0f, zerodegree, zerodegree),                osg::inDegrees(zerodegree), osg::Vec3(zerodegree, 1.0f, zerodegree),                osg::inDegrees(90.0f), osg::Vec3(zerodegree, zerodegree, 1.0f)                ));        }            break;        default:            break;        }    }}// 暴露接口 设置Hud视口的位置和大小 以及我们导航立方体的大小void CHUDPickHandler::setHudViewPositionAndCubeWidth(double _x, double _y, double _width, double _height, float _cubeWidth){    m_pViewport = new osg::Viewport(_x, _y, _width, _height);    m_cubeWidth = _cubeWidth;}// 创建场景信息void CHUDPickHandler::createSceneNode(osg::ref_ptr<osgViewer::Viewer> _viewer, osg::ref_ptr<osg::Group> _root){    osg::GraphicsContext::WindowingSystemInterface* wsi = osg::GraphicsContext::getWindowingSystemInterface();    unsigned int width, height;    wsi->getScreenResolution(osg::GraphicsContext::ScreenIdentifier(0), width, height);    osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits();    traits->x = 0;    traits->y = 0;    traits->width = width;    traits->height = height;    traits->windowDecoration = true;    traits->doubleBuffer = true;    traits->sharedContext = 0;    //    osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits);    // 操作主相机    osg::Camera* masterCamera = _viewer->getCamera();    masterCamera->setGraphicsContext(gc);    masterCamera->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));    masterCamera->setDrawBuffer(GL_BACK);    masterCamera->setReadBuffer(GL_BACK);    // 设置从属相机    m_pHudCamera = new osg::Camera;    m_pHudCamera->setGraphicsContext(gc);    m_pHudCamera->setAllowEventFocus(true);    // 投影矩阵的大小范围    m_pHudCamera->setProjectionMatrixAsOrtho2D(        -1.0f * traits->height * 0.2f,        traits->height * 0.2f,        -1.0f * traits->height * 0.2f,        traits->height * 0.2f);    m_pHudCamera->setDrawBuffer(GL_BACK);    m_pHudCamera->setReadBuffer(GL_BACK);    m_pHudCamera->setRenderOrder(osg::Camera::POST_RENDER);    m_pHudCamera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);    m_pHudCamera->addChild(createCustomCubeGeometry());    // 将相机固定位置    m_pHudCamera->setViewMatrixAsLookAt(        osg::Vec3(0, -1000 * m_cubeWidth, 0),        osg::Vec3(0, 0, 0),         osg::Vec3(0, 0, 1)        );    // 设置HUD视图位置    m_pHudCamera->setViewport(m_pViewport);    // 这里使用addChild时，只能旋转导航器，导航器不响应点击事件 还在找原因 addSlave没问题    _viewer->addSlave(m_pHudCamera, false);    //_root->addChild(m_pHudCamera);    // 旋转操作    _viewer->setCameraManipulator(m_pTrackballManipulator);    // 点击事件    _viewer->addEventHandler(this);}// 初始化我们绘制立方体所需要的顶点 纹理坐标 以及决定一个面所需要的顶点下标void CHUDPickHandler::initVertexAndNormalData(){    // 立方体的顶点信息    m_vec3VerCoords = new osg::Vec3Array(8);    (*m_vec3VerCoords)[0] = osg::Vec3(m_cubeWidth, m_cubeWidth, m_cubeWidth);    (*m_vec3VerCoords)[1] = osg::Vec3(-1.0f * m_cubeWidth, m_cubeWidth, m_cubeWidth);    (*m_vec3VerCoords)[2] = osg::Vec3(m_cubeWidth, -1.0f * m_cubeWidth, m_cubeWidth);    (*m_vec3VerCoords)[3] = osg::Vec3(-1.0f * m_cubeWidth, -1.0f * m_cubeWidth, m_cubeWidth);    (*m_vec3VerCoords)[4] = osg::Vec3(m_cubeWidth, m_cubeWidth, -1.0f * m_cubeWidth);    (*m_vec3VerCoords)[5] = osg::Vec3(-1.0f * m_cubeWidth, m_cubeWidth, -1.0f * m_cubeWidth);    (*m_vec3VerCoords)[6] = osg::Vec3(m_cubeWidth, -1.0f * m_cubeWidth, -1.0f * m_cubeWidth);    (*m_vec3VerCoords)[7] = osg::Vec3(-1.0f * m_cubeWidth, -1.0f * m_cubeWidth, -1.0f * m_cubeWidth);    // 立方体的纹理坐标    m_vec2TexCoords = new osg::Vec2Array(4);    (*m_vec2TexCoords)[0] = osg::Vec2(0.0f, 0.0f);    (*m_vec2TexCoords)[1] = osg::Vec2(1.0f, 0.0f);    (*m_vec2TexCoords)[2] = osg::Vec2(1.0f, 1.0f);    (*m_vec2TexCoords)[3] = osg::Vec2(0.0f, 1.0f);    // 组成面的顶点    m_vec4FaceVertexs = new osg::Vec4iArray(6);    (*m_vec4FaceVertexs)[0] = osg::Vec4i(7, 6, 2, 3);    (*m_vec4FaceVertexs)[1] = osg::Vec4i(4, 5, 1, 0);    (*m_vec4FaceVertexs)[2] = osg::Vec4i(3, 2, 0, 1);    (*m_vec4FaceVertexs)[3] = osg::Vec4i(5, 4, 6, 7);    (*m_vec4FaceVertexs)[4] = osg::Vec4i(5, 7, 3, 1);    (*m_vec4FaceVertexs)[5] = osg::Vec4i(6, 4, 0, 2);}// 创建导航器立方体osg::Geode* CHUDPickHandler::createCustomCubeGeometry(){    initVertexAndNormalData();    //    osg::Geode* geode = new osg::Geode;    char imagePath[64];    char faceName[16];    for (int i = 0; i < 6; i++)    {        sprintf(imagePath, "D:\\softwares\\side%d.png", i + 1);        sprintf(faceName, "%d", i);        osg::Image* image = osgDB::readImageFile(imagePath);        osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;        // 顶点        osg::ref_ptr<osg::Vec3Array> coords = new osg::Vec3Array(4);        osg::Vec4i v4 = (*m_vec4FaceVertexs)[i];        (*coords)[0] = (*m_vec3VerCoords)[v4.x()];        (*coords)[1] = (*m_vec3VerCoords)[v4.y()];        (*coords)[2] = (*m_vec3VerCoords)[v4.z()];        (*coords)[3] = (*m_vec3VerCoords)[v4.w()];        geom->setVertexArray(coords);        // 法线        osg::ref_ptr<osg::Vec3Array> norm = new osg::Vec3Array(1);        (*norm)[0] = ((*coords)[0] - (*coords)[1]) ^ ((*coords)[1] - (*coords)[2]);        (*norm)[0].normalize();        geom->setNormalArray(norm, osg::Array::BIND_OVERALL);        // 纹理坐标        osg::ref_ptr<osg::Vec2Array> tcoords = new osg::Vec2Array(4);        (*tcoords)[0] = osg::Vec2(0.0f, 0.0f);        (*tcoords)[1] = osg::Vec2(1.0f, 0.0f);        (*tcoords)[2] = osg::Vec2(1.0f, 1.0f);        (*tcoords)[3] = osg::Vec2(0.0f, 1.0f);        geom->setTexCoordArray(0, tcoords);        geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS, 0, coords->size()));        geom->setName(faceName);        if (image)        {            osg::ref_ptr<osg::StateSet> stateset = new osg::StateSet;            osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D;            texture->setImage(image);            stateset->setTextureAttributeAndModes(0, texture, osg::StateAttribute::ON);            geom->setStateSet(stateset);        }        geode->addChild(geom);    }    // 创建一个纹理地图    {        osg::Image* image = osgDB::readImageFile("D:\\softwares\\compass_plate.PNG");        osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;        // 顶点        osg::ref_ptr<osg::Vec3Array> coords = new osg::Vec3Array(4);        float planeWidth = 1.5f * m_cubeWidth;        (*coords)[0] = osg::Vec3(-1.0f * planeWidth, planeWidth, -1.01f * m_cubeWidth);        (*coords)[1] = osg::Vec3(planeWidth, planeWidth, -1.01f * m_cubeWidth);        (*coords)[2] = osg::Vec3(planeWidth, -1.0f * planeWidth, -1.01f * m_cubeWidth);        (*coords)[3] = osg::Vec3(-1.0f * planeWidth, -1.0f * planeWidth, -1.01f * m_cubeWidth);        geom->setVertexArray(coords);        // 法线        osg::ref_ptr<osg::Vec3Array> norm = new osg::Vec3Array(1);        (*norm)[0] = ((*coords)[1] - (*coords)[0]) ^ ((*coords)[2] - (*coords)[1]);        (*norm)[0].normalize();        geom->setNormalArray(norm, osg::Array::BIND_OVERALL);        // 纹理坐标        osg::ref_ptr<osg::Vec2Array> tcoords = new osg::Vec2Array(4);        (*tcoords)[0] = osg::Vec2(0.0f, 0.0f);        (*tcoords)[1] = osg::Vec2(1.0f, 0.0f);        (*tcoords)[2] = osg::Vec2(1.0f, 1.0f);        (*tcoords)[3] = osg::Vec2(0.0f, 1.0f);        geom->setTexCoordArray(0, tcoords);        geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS, 0, coords->size()));        geom->setName("3");        if (image)        {            osg::ref_ptr<osg::StateSet> stateset = new osg::StateSet;            osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D;            osg::ref_ptr<osg::BlendColor> bc = new osg::BlendColor(osg::Vec4(1.0f, 1.0f, 1.0f, 0.0f));            osg::ref_ptr<osg::BlendFunc> bf = new osg::BlendFunc();            texture->setImage(image);            // 添加纹理效果            stateset->setTextureAttributeAndModes(0, texture, osg::StateAttribute::ON);            stateset->setMode(GL_BLEND, osg::StateAttribute::ON);            stateset->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);            stateset->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);            stateset->setAttributeAndModes(bf, osg::StateAttribute::ON);            stateset->setAttributeAndModes(bc, osg::StateAttribute::ON);            bf->setSource(osg::BlendFunc::CONSTANT_ALPHA);            bf->setDestination(osg::BlendFunc::ONE_MINUS_CONSTANT_ALPHA);            bc->setConstantColor(osg::Vec4(1.0f, 1.0f, 1.0f, 0.5f));            geom->setStateSet(stateset);        }        geode->addChild(geom);    }    return geode;}

以上就是我们的CHUDPickHandler.cpp的实现过程。So，接下来我们看下如何使用：

#include "CHUDEventHandler.h"#include <osgDB/ReadFile>#include <osgUtil/Optimizer>// 模型参数， 导航器模型大小int main(int argc, char** argv){    osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;    osg::ref_ptr<osg::Group> root = new osg::Group;    osg::ref_ptr<osg::Node> cow = osgDB::readNodeFile("cow.osg");    CHUDPickHandler* cHudPickHandler = new CHUDPickHandler();    // 设置HUD视图的位置和导航立方体的大小    cHudPickHandler->setHudViewPositionAndCubeWidth(200.0, 20.0, 300.0, 300.0);    // 添加Hud视图    cHudPickHandler->createSceneNode(viewer, root);    // 添加主场景模型    root->addChild(cow);    osgUtil::Optimizer op;    op.optimize(root);    viewer->setSceneData(root);    viewer->realize();    viewer->run();    return 0;}

上面就是main函数的实现过程。整个实现的核心就是保证Hud相机随漫游器同步旋转。提供所需要的图片就是看到让你笑开花的效果了。