實現功能

自定義相機的位置位于世界坐標系下的Y軸正方向斜向下45度觀察水平面。通過按鍵實現向前（按W）向后（按S）向左（按A）向右（按D）向上（按PageUp）向下（按PageDown）相機左右旋轉(J/L)、相機上下旋轉（I/K）

觀察效果如圖：

基礎知識

實現相機我們所要用到的知識點有1.向量，矩陣，四元素等概念2.OSG坐標系統的知識。3.視圖與相機， 鍵盤事件消息處理的相關知識。最重要的需要自己的空間思維能力，如果對以上的知識點不熟悉的話，可以去相關的網站看看。

實現原理

一.新建一個類共有繼承 osgGA::CameraManipulator，并且重寫四個虛函數，具體的代碼需要根據要求來進行編寫。1.virtual void setByMatrix(const osg::Matrixd& matrix);2.virtual void setByInverseMatrix(const osg::Matrixd& matrix) ;3.virtual osg::Matrixd getMatrix() const ;4.virtual osg::Matrixd getInverseMatrix() const ;二.進行鍵盤事件處理我們需要重寫handle函數1.virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& us) ;

代碼實現

.h文件

class TraveManipulator :public osgGA::CameraManipulator { public://構造函數TraveManipulator(osg::ref_ptr<osg::Node> node1);//析構函數~TraveManipulator();//設置矩陣virtual void setByMatrix(const osg::Matrixd& matrix);//設置逆矩陣virtual void setByInverseMatrix(const osg::Matrixd& matrix) ;//得到矩陣virtual osg::Matrixd getMatrix() const ;//得到逆矩陣virtual osg::Matrixd getInverseMatrix() const ;//鍵盤事件處理函數virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& us) ; private://視點位置osg::Vec3d m_Eye;//參照物中心osg::Vec3d m_Center;//方向向量osg::Vec3d m_Up;//距離double m_Distense;//移動步長float m_Step;//旋轉矩陣osg::Matrix m_RotationMatrix;//相機上下旋轉的繞軸osg::Vec3 m_CameraRotation; };

.cpp文件

TraveManipulator::TraveManipulator(osg::ref_ptr<osg::Node> node1) :m_Distense(4000.0), m_Step(30) {//保存物體的中心點osg::Vec3d node_Center = node1->getBound().center();osg::Matrix rotation_Anngle;//繞x軸旋轉45°rotation_Anngle = osg::Matrix::rotate(osg::Quat(-osg::PI_4,osg::Vec3f(1.0f, 0.0f, 0.0f)));//設置視點的位置,m_Eye = osg::Vec3d(0.0, 0.0, m_Distense);//設置中心點的位置m_Center = node_Center;//up向量m_Up = osg::Vec3d(0.0,- 1.0, 0.0);//視點位于Y軸的正方向斜向上45°m_Eye = m_Eye * rotation_Anngle;m_Up = m_Up * rotation_Anngle;m_CameraRotation = osg::Vec3(1.0f,0.0f,0.0f); } TraveManipulator::~TraveManipulator() { // } //設置矩陣 void TraveManipulator::setByMatrix(const osg::Matrixd& matrix) {// } //設置逆矩陣 void TraveManipulator::setByInverseMatrix(const osg::Matrixd& matrix) {// } //得到矩陣,用于控制場景 osg::Matrixd TraveManipulator::getMatrix() const {return osg::Matrixd(); } //得到逆矩陣 osg::Matrixd TraveManipulator::getInverseMatrix() const {return osg::Matrixd::lookAt(m_Eye,m_Center,m_Up); } //鍵盤事件處理函數 bool TraveManipulator::handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& us) {//獲取事件switch (ea.getEventType()){//如果是一個鍵盤事件case osgGA::GUIEventAdapter::KEYDOWN:{//向前移動（按W）if(ea.getKey() == 'w' || ea.getKey() == 'W'){m_Eye = m_Eye * osg::Matrix::translate(osg::Vec3(0.0,m_Step,0.0) * m_RotationMatrix);m_Center = m_Center * osg::Matrix::translate(osg::Vec3(0.0,m_Step,0.0) * m_RotationMatrix);} //向后移動（按s）else if (ea.getKey() == 's' || ea.getKey() == 'S'){m_Eye = m_Eye * osg::Matrix::translate(osg::Vec3(0.0,-m_Step,0.0) * m_RotationMatrix);m_Center = m_Center * osg::Matrix::translate(osg::Vec3(0.0,-m_Step,0.0) * m_RotationMatrix);}//向左移動（按a）else if (ea.getKey() == 'a' || ea.getKey() == 'A'){m_Eye = m_Eye * osg::Matrix::translate(osg::Vec3(-m_Step,0.0,0.0) * m_RotationMatrix);m_Center = m_Center * osg::Matrix::translate(osg::Vec3(-m_Step,0.0,0.0) * m_RotationMatrix);}//向右移動（按d）else if (ea.getKey() == 'd' || ea.getKey() == 'D'){m_Eye = m_Eye * osg::Matrix::translate(osg::Vec3(m_Step,0.0,0.0) * m_RotationMatrix);m_Center = m_Center * osg::Matrix::translate(osg::Vec3(m_Step,0.0,0.0) * m_RotationMatrix);}//向上移動（按Page UP）else if (ea.getKey() == 0XFF55){m_Eye = m_Eye * osg::Matrix::translate(osg::Vec3(m_Step,0.0,0.0) * m_RotationMatrix)*osg::Matrix::translate(osg::Vec3(0.0,m_Step,0.0) * m_RotationMatrix)*osg::Matrix::translate(osg::Vec3(0.0,0.0, m_Step) * m_RotationMatrix)*osg::Matrix::translate(osg::Vec3(-m_Step,0.0,0.0)* m_RotationMatrix);}//向下移動（按Page Down)else if (ea.getKey() == 0xFF56){m_Eye = m_Eye * osg::Matrix::translate(osg::Vec3(m_Step,0.0,0.0) * m_RotationMatrix)*osg::Matrix::translate(osg::Vec3(0.0,-m_Step,0.0) * m_RotationMatrix)*osg::Matrix::translate(osg::Vec3(0.0,0.0,-m_Step) * m_RotationMatrix)*osg::Matrix::translate(osg::Vec3(-m_Step,0.0,0.0) * m_RotationMatrix);} //相機向左旋轉else if (ea.getKey() == 'j' || ea.getKey() == 'J'){osg::Matrix mt; //設置旋轉軸mt = osg::Matrixd::rotate(-osg::DegreesToRadians(15.0),osg::Vec3(0.0f,0.0f,1.0f));m_CameraRotation = m_CameraRotation * mt;m_RotationMatrix = m_RotationMatrix * mt ;m_Eye = m_Eye * mt;m_Up = m_Up * mt;m_Center = m_Center * mt;}//相機向右旋轉else if (ea.getKey() == 'l' || ea.getKey() == 'L'){osg::Matrix mt;//設置旋轉軸mt = osg::Matrixd::rotate(osg::DegreesToRadians(15.0),osg::Vec3(0.0f,0.0f,1.0f));m_CameraRotation = m_CameraRotation * mt;m_RotationMatrix = m_RotationMatrix * mt;m_Eye = m_Eye * mt;m_Up = m_Up * mt;m_Center = m_Center * mt;}//相機向上旋轉else if (ea.getKey() == 'i' || ea.getKey() == 'I'){osg::Matrix mt;//設置旋轉軸mt = osg::Matrix::rotate(osg::DegreesToRadians(15.0),m_CameraRotation);m_RotationMatrix = m_RotationMatrix* mt;m_Eye = m_Eye * osg::Matrix::rotate(osg::DegreesToRadians(15.0),m_CameraRotation);m_Up = m_Up * osg::Matrix::rotate(osg::DegreesToRadians(15.0),m_CameraRotation);m_Center = m_Center * osg::Matrix::rotate(osg::DegreesToRadians(15.0),m_CameraRotation);}//相機向下旋轉else if (ea.getKey() == 'k' || ea.getKey() == 'K'){osg::Matrix mt;//設置旋轉矩陣mt = osg::Matrix::rotate(-osg::DegreesToRadians(15.0),m_CameraRotation);m_RotationMatrix = m_RotationMatrix * mt;m_Eye = m_Eye * osg::Matrix::rotate(-osg::DegreesToRadians(15.0),m_CameraRotation);m_Up = m_Up * osg::Matrix::rotate(-osg::DegreesToRadians(15.0),m_CameraRotation);m_Center = m_Center * osg::Matrix::rotate(-osg::DegreesToRadians(15.0),m_CameraRotation);}}default:break;return false;}return false; }

main.cpp文件

#include "Trave.h" #include "Setup.h" int main() {osg::ref_ptr<osgViewer::Viewer>viewer = new osgViewer::Viewer();osg::ref_ptr<osg::Group> root = new osg::Group();Changeport a(viewer);a.changeport();osg::ref_ptr<osg::Node> node = a.createNode();root->addChild(a.createTexture2DState(node));//添加漫游器viewer->setCameraManipulator(new TraveManipulator(node));osgUtil::Optimizer optimizer;optimizer.optimize(root.get());//設置場景數據viewer->setSceneData(root.get());viewer->realize();viewer->run(); return 0; }

這是我對相機的理解和看法，代碼僅供參考。如果大家有什么不同的意見，歡迎評論區留言

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