Osg-地图界面显示指北针（指南针）

相关资料：

https://blog.csdn.net/zbf00138/article/details/52288598

实例：

Compass.h

 1 #ifndef COMPASS_H
 2 #define COMPASS_H
 3 
 4 #include <osgEarth/MapNode>
 5 
 6 #include <osgEarthUtil/EarthManipulator>
 7 #include <osgEarthUtil/ExampleResources>
 8 
 9 #include <osgEarthAnnotation/ImageOverlay>
10 #include <osgEarthAnnotation/CircleNode>
11 #include <osgEarthAnnotation/RectangleNode>
12 #include <osgEarthAnnotation/EllipseNode>
13 #include <osgEarthAnnotation/PlaceNode>
14 #include <osgEarthAnnotation/LabelNode>
15 #include <osgEarthAnnotation/LocalGeometryNode>
16 #include <osgEarthAnnotation/FeatureNode>
17 #include <osgEarthAnnotation/ModelNode>
18 
19 #include <osgEarthAnnotation/AnnotationEditing>
20 #include <osgEarthAnnotation/ImageOverlayEditor>
21 
22 #include <osgEarthSymbology/GeometryFactory>
23 #include <osgEarthUtil/RTTPicker>
24 
25 #include <osgViewer/Viewer>
26 #include <osgQOpenGL/osgQOpenGLWidget>
27 #include <osg/DrawPixels>
28 
29 class Compass : public osg::Camera
30 {
31 public:
32     Compass();
33     Compass( const Compass& copy, osg::CopyOp copyop=osg::CopyOp::SHALLOW_COPY );
34     META_Node( osg, Compass );
35 
36 
37     void setPlate( osg::MatrixTransform* plate ) { _plateTransform = plate; }
38     osg::MatrixTransform* getPlate() { return _plateTransform.get(); }
39     const osg::MatrixTransform* getPlate() const { return _plateTransform.get(); }
40 
41 
42     void setNeedle( osg::MatrixTransform* needle ) { _needleTransform = needle; }
43     osg::MatrixTransform* getNeedle() { return _needleTransform.get(); }
44     const osg::MatrixTransform* getNeedle() const { return _needleTransform.get(); }
45 
46 
47     void setMainCamera( osg::Camera* camera ) { _mainCamera = camera; }
48     osg::Camera* getMainCamera() { return _mainCamera.get(); }
49     const osg::Camera* getMainCamera() const { return _mainCamera.get(); }
50     void setWidthHeight(int x, int y, int width, int height){ m_xx = x; m_yy = y; m_width = width; m_height = height; };
51     virtual void traverse( osg::NodeVisitor& nv );
52 
53 protected:
54     virtual ~Compass();
55     int m_width, m_height;
56     int m_x, m_y, m_xx, m_yy;
57     osg::ref_ptr<osg::MatrixTransform> _plateTransform;
58     osg::ref_ptr<osg::MatrixTransform> _needleTransform;
59     osg::observer_ptr<osg::Camera> _mainCamera;
60 };
61 
62 #endif // COMPASS_H

View Code

Compass.cpp

 1 #include "Compass.h"
 2 
 3 
 4 Compass::Compass()
 5 {
 6 }
 7 
 8 Compass::Compass( const Compass& copy, osg::CopyOp copyop )
 9 :   osg::Camera(copy, copyop),
10     _plateTransform(copy._plateTransform),
11     _needleTransform(copy._needleTransform),
12     _mainCamera(copy._mainCamera)
13 {
14 }
15 
16 Compass::~Compass()
17 {
18 }
19 
20 void Compass::traverse( osg::NodeVisitor& nv )
21 {
22     if ( _mainCamera.valid() && nv.getVisitorType()==osg::NodeVisitor::CULL_VISITOR )
23     {
24         osg::Matrix matrix = _mainCamera->getViewMatrix();
25         matrix.setTrans( osg::Vec3() );
26 
27         osg::Vec3 northVec = osg::Z_AXIS * matrix;
28         northVec.z() = 0.0f;
29         northVec.normalize();
30 
31         osg::Vec3 axis = osg::Y_AXIS ^ northVec;
32         float angle = atan2(axis.length(), osg::Y_AXIS*northVec);
33         axis.normalize();
34 
35         if ( _plateTransform.valid() )
36             _plateTransform->setMatrix( osg::Matrix::rotate(angle, axis) );
37 
38         if (m_x != _mainCamera->getViewport()->width() || _mainCamera->getViewport()->height() != m_y)
39         {
40             m_x = _mainCamera->getViewport()->width();
41             m_y = _mainCamera->getViewport()->height();
42             this->setViewport(_mainCamera->getViewport()->width()-m_width-m_xx, _mainCamera->getViewport()->height()-m_height-m_yy, m_width, m_height);
43         }
44     }
45 
46 
47     _plateTransform->accept( nv );
48     _needleTransform->accept( nv );
49     osg::Camera::traverse( nv );
50 }

View Code

调用

 1     osg::ref_ptr<Compass> compass = new Compass;
 2     compass->setProjectionMatrix(osg::Matrixd::ortho(-1.5, 1.5, -1.5, 1.5, -10.0, 10.0));
 3     compass->setPlate(createCompassPart("d:\a.png", 1.5f, -1.0f)); //圆盘图片
 4     compass->setNeedle(createCompassPart("d:\b.png", 1.5f, 0.0f));//指针图片
 5     compass->setWidthHeight(100,100,100,100); //起始点、宽高
 6     compass->setMainCamera(m_pViewer->getCamera());
 7 
 8     compass->setRenderOrder(osg::Camera::POST_RENDER);
 9     compass->setClearMask(GL_DEPTH_BUFFER_BIT);
10     compass->setAllowEventFocus(false);
11     compass->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
12     compass->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
13     compass->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);
14 
15     m_pRoot->addChild(compass); //加入跟节点

View Code

createCompassPart函数

 1 osg::MatrixTransform *Widget::createCompassPart(const std::string &image, float radius, float height)
 2 {
 3     osg::Vec3 center(-radius, -radius, height);
 4     osg::ref_ptr<osg::Geode> geode = new osg::Geode;
 5     geode->addDrawable(
 6         createTexturedQuadGeometry(center, osg::Vec3(radius*2.0f, 0.0f, 0.0f), osg::Vec3(0.0f, radius*2.0f, 0.0f)));
 7 
 8     osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D;
 9     texture->setImage(osgDB::readImageFile(image));
10 
11     osg::ref_ptr<osg::MatrixTransform> part = new osg::MatrixTransform;
12     part->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture.get());
13     part->getOrCreateStateSet()->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
14     part->addChild(geode.get());
15     return part.release();
16 }

View Code

作者：疯狂Delphi

出处：https://www.cnblogs.com/FKdelphi/

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