HUD抬头显示

HUD抬头显示

基本方法：

1）  创建一个camera

2）  设置camera的投影矩阵为osg::Matrix::ortho2D(0,width,0,height)

3）  设置camera的坐标系为绝对坐标系

4）  设置camera的视图矩阵为单位矩阵

5）  设置camera的清除掩码只是深度缓存

6）  设置camera的渲染顺序是最后渲染

7）  关闭光照和深度测试

类似现：

头文件：

#pragma once

//单件设计模式，只有一个实例

#include "osginlude.h"

class MyHUD :

     public osg::Camera

{

public:

     MyHUD(void);

public:

     virtual ~MyHUD(void);

     static MyHUD *GetPtr();

     void AddHUDText(std::string);

 

private:

     int lineNum;

     int charNumPerLine;

     osg::Vec4 color;

     static MyHUD *myhud;

     std::list<std::string> strlist;

     osg::ref_ptr<osgText::Text> HUDText;

     osg::Vec3 position;

};

 

源文件

 

#include "MyHUD.h"

MyHUD *MyHUD::myhud=NULL;

MyHUD::MyHUD(void):color(1.0f,1.0,0.8f,0.2f)

,lineNum(5)

,charNumPerLine(20)

,position(150.0f,800.0f,0.0f)

{

     //设置数据是变更的

     this->setDataVariance(osg::Geometry::DYNAMIC);

     //创建一个摄像机，用它来设置投影矩阵和模型视图矩阵

     //以及用来显示HUD的子节点

     osg::Camera* camera = this;

 

     //得到屏幕分辨率

     unsigned int width, height;

     osg::GraphicsContext::WindowingSystemInterface* wsi = osg::GraphicsContext::getWindowingSystemInterface();

     if (!wsi)

     {

         osg::notify(osg::NOTICE)<<"Error, no WindowSystemInterface available, cannot create windows."<<std::endl;

         return ;

     }

     wsi->getScreenResolution(osg::GraphicsContext::ScreenIdentifier(0), width, height);

 

     //建立投影矩阵

     camera->setProjectionMatrix(osg::Matrix::ortho2D(0,width,0,height));

 

     // 设定视图矩阵

     camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);

     camera->setViewMatrix(osg::Matrix::identity());

 

     //只清除深度缓存

     camera->setClearMask(GL_DEPTH_BUFFER_BIT);

 

     //设置摄像机子图的渲染顺序，这个顺序相对于这个子图所在的所有摄像机。

     //对于渲染到纹理，应设置PRE_RENDER，对于HUD，设置为POST_RENDER

     camera->setRenderOrder(osg::Camera::POST_RENDER);

 

     //不处理主摄像机传递过来的事件

     camera->setAllowEventFocus(false);

 

     osg::Geode* geode = new osg::Geode();

 

     std::string timesFont("simsun.ttc");

 

     // turn lighting off for the text and disable depth test to ensure its always ontop.

     osg::StateSet* stateset = geode->getOrCreateStateSet();

     stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);

 

 

     HUDText=new  osgText::Text;

     geode->addDrawable( HUDText.get() );

     HUDText->setFont(timesFont);

     HUDText->setPosition(position);

     HUDText->setText("");

     HUDText->setDataVariance(osg::Geometry::DYNAMIC);

 

     osg::BoundingBox bb;

     for(unsigned int i=0;i<geode->getNumDrawables();++i)

     {

         bb.expandBy(geode->getDrawable(i)->getBound());

     }

 

     osg::Geometry* geom = new osg::Geometry;

 

     osg::Vec3Array* vertices = new osg::Vec3Array;

     float depth = bb.zMin()-0.1;

     vertices->push_back(osg::Vec3(bb.xMin(),bb.yMax(),depth));

     vertices->push_back(osg::Vec3(bb.xMin(),bb.yMin(),depth));

     vertices->push_back(osg::Vec3(bb.xMax(),bb.yMin(),depth));

     vertices->push_back(osg::Vec3(bb.xMax(),bb.yMax(),depth));

     geom->setVertexArray(vertices);

 

     osg::Vec3Array* normals = new osg::Vec3Array;

     normals->push_back(osg::Vec3(0.0f,0.0f,1.0f));

     geom->setNormalArray(normals);

     geom->setNormalBinding(osg::Geometry::BIND_OVERALL);

 

     osg::Vec4Array* colors = new osg::Vec4Array;

     colors->push_back(osg::Vec4(1.0f,1.0,0.8f,0.2f));

     geom->setColorArray(colors);

     geom->setColorBinding(osg::Geometry::BIND_OVERALL);

 

     geom->addPrimitiveSet(new osg::DrawArrays(GL_QUADS,0,4));

 

     //设置颜色的混合，启动透明以按深度排序

//   osg::StateSet* stateset = geom->getOrCreateStateSet();

     stateset->setMode(GL_BLEND,osg::StateAttribute::ON);

     stateset->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);

 

     geode->addDrawable(geom);

     camera->addChild(geode);

}

 

MyHUD::~MyHUD(void)

{

}

MyHUD * MyHUD::GetPtr()

{

     if (NULL==myhud)

     {

         myhud=new MyHUD;

     }

     return myhud;

}

void MyHUD::AddHUDText(std::string str)

{

     while (str.size()>(size_t)charNumPerLine)

     {

         strlist.push_back(std::string(str.begin(),str.begin()+charNumPerLine));

         str.erase(str.begin(),str.begin()+charNumPerLine);

     }

     if(str.size()>0)

         strlist.push_back(str);

     while(strlist.size()>(size_t)lineNum)

         strlist.pop_front();

     //得到文本

     std::string HUDstr;

     std::list<std::string>::iterator it;

     for(it=strlist.begin();it!=strlist.end();it++)

         HUDstr=HUDstr+*it+"/n";

     HUDText->setText(HUDstr);

}

 

调用方法：

viewer.setSceneData(MyHUD::GetPtr());

MyHUD::GetPtr()->AddHUDText(str);