由于工作需要，重新?lián)炝讼聅hader。很明顯，fbo是重中之重。好記性不如爛筆頭，先記錄下

1，生成一個顏色紋理(為了省事，可以將紋理寬高=屏幕寬高)

osg::ref_ptr<osg::Texture2D> tex = createFloatRectangleTexture(texWidth, texHeight);

2,采樣攝像機(jī)添加場景根，并把場景根的顏色緩沖區(qū)與紋理關(guān)聯(lián)，

sampleCamera->addChild(sceneRoot);sampleCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT); //這句話使內(nèi)容不渲染到屏幕上sampleCamera->attach(osg::Camera::COLOR_BUFFER0, tex); //關(guān)聯(lián)顏色貼圖

3，將紋理關(guān)聯(lián)到面片上，以方便加載使用

osg::ref_ptr<osg::Geode> panelGeode = createTexturePanelGeode(); osg::ref_ptr<osg::StateSet> ss = panelGeode->getOrCreateStateSet(); ss->setTextureAttributeAndModes(0, tex);

4，這個面片關(guān)聯(lián)的紋理，由于是在攝像機(jī)坐標(biāo)系下，所以要規(guī)格化坐標(biāo)系，位置【-1,1】
紋理坐標(biāo)【0,1】

osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array; vertices->push_back(osg::Vec3(-1.0f, -1.0f, 0.0f)); vertices->push_back(osg::Vec3(1.0f, -1.0f, 0.0f)); vertices->push_back(osg::Vec3(1.0f, 1.0f, 0.0f)); vertices->push_back(osg::Vec3(-1.0f, 1.0f, 0.0f));osg::ref_ptr<osg::Vec2Array> texCoord = new osg::Vec2Array; texCoord->push_back(osg::Vec2(0.0, 0.0)); texCoord->push_back(osg::Vec2(1.0, 0.0)); texCoord->push_back(osg::Vec2(1.0, 1.0)); texCoord->push_back(osg::Vec2(0.0, 1.0));

4，三維轉(zhuǎn)二維，就是貼圖片的過程，FBO中的圖片一般還要進(jìn)行一個圖像處理，所以要設(shè)置一個passRoot，用于顯示。這個passroot要同時包含采樣攝像機(jī)和面片才行。

passRoot->addChild(sampleCamera); //將攝像機(jī)加入場景 passRoot->addChild(panelGeode); viewer->setSceneData(passRoot);

運(yùn)行結(jié)果如下：

代碼如下：

#include <osgDB/ReadFile>
#include <osgUtil/Optimizer>
#include <osg/CoordinateSystemNode>

#include <osg/Switch>
#include <osg/Types>
#include <osgText/Text>

#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>

#include <osgGA/TrackballManipulator>
#include <osgGA/FlightManipulator>
#include <osgGA/DriveManipulator>
#include <osgGA/KeySwitchMatrixManipulator>
#include <osgGA/StateSetManipulator>
#include <osgGA/AnimationPathManipulator>
#include <osgGA/TerrainManipulator>
#include <osgGA/SphericalManipulator>

#include <osgGA/Device>
#include <osg/Shader>

osg::ref_ptrosg::Texture2D createFloatRectangleTexture(int width, int height)
{
osg::ref_ptrosg::Texture2D tex2D = new osg::Texture2D;
tex2D->setTextureSize(width, height);
tex2D->setInternalFormat(GL_RGBA16F_ARB);
tex2D->setSourceFormat(GL_RGBA);
tex2D->setSourceType(GL_FLOAT);
return tex2D.release();
}
osg::ref_ptrosg::Geode createTexturePanelGeode()
{
osg::ref_ptrosg::Vec3Array vertices = new osg::Vec3Array;
vertices->push_back(osg::Vec3(-1.0f, -1.0f, 0.0f));
vertices->push_back(osg::Vec3(1.0f, -1.0f, 0.0f));
vertices->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
vertices->push_back(osg::Vec3(-1.0f, 1.0f, 0.0f));

osg::ref_ptr<osg::Vec2Array> texCoord = new osg::Vec2Array; texCoord->push_back(osg::Vec2(0.0, 0.0)); texCoord->push_back(osg::Vec2(1.0, 0.0)); texCoord->push_back(osg::Vec2(1.0, 1.0)); texCoord->push_back(osg::Vec2(0.0, 1.0));osg::ref_ptr<osg::Geometry> geom = new osg::Geometry; geom->setVertexArray(vertices); geom->setTexCoordArray(0, texCoord); geom->addPrimitiveSet(new osg::DrawArrays(GL_QUADS, 0, 4));osg::ref_ptr<osg::Geode> geode = new osg::Geode; geode->addDrawable(geom); osg::ref_ptr<osg::StateSet> set1 = geode->getOrCreateStateSet(); set1->setMode(GL_LIGHTING, osg::StateAttribute::OFF); //設(shè)置不受光照影響，不然太暗了就看不清楚 return geode;

}

int main()
{
osg::ref_ptrosgViewer::Viewer viewer = new osgViewer::Viewer;
std::string strFileName = “D:/OpenSceneGraph-master/OpenSceneGraph-Data-master/cow.osg”;
//pass1的根
osg::ref_ptrosg::Group passRoot = new osg::Group();
//場景根
osg::ref_ptrosg::Group sceneRoot = new osg::Group();
osg::ref_ptrosg::Node node = osgDB::readNodeFile(strFileName);
sceneRoot->addChild(node);

//獲取系統(tǒng)分辨率 unsigned int screenWidth, screenHeight; osg::GraphicsContext::WindowingSystemInterface * wsInterface = osg::GraphicsContext::getWindowingSystemInterface(); if (!wsInterface) {return -1; } wsInterface->getScreenResolution(osg::GraphicsContext::ScreenIdentifier(0), screenWidth, screenHeight); int texWidth = screenWidth; int texHeight = screenHeight; osg::ref_ptr<osg::Texture2D> tex = createFloatRectangleTexture(texWidth, texHeight); //綁定采樣攝像機(jī) osg::ref_ptr<osg::Camera> sampleCamera = new osg::Camera; {sampleCamera->addChild(sceneRoot);sampleCamera->setClearColor(osg::Vec4(0.0f, 0.0f, 0.0f, 1.0f));sampleCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT); //這句話使內(nèi)容不渲染到屏幕上sampleCamera->attach(osg::Camera::COLOR_BUFFER0, tex); //關(guān)聯(lián)顏色貼圖//攝像機(jī)關(guān)聯(lián)視口sampleCamera->setViewport(0, 0, screenWidth, screenHeight);} osg::ref_ptr<osg::Geode> panelGeode = createTexturePanelGeode(); osg::ref_ptr<osg::StateSet> ss = panelGeode->getOrCreateStateSet(); ss->setTextureAttributeAndModes(0, tex);

;
passRoot->addChild(sampleCamera); //將攝像機(jī)加入場景
passRoot->addChild(panelGeode);
viewer->setSceneData(passRoot);
viewer->run();
return 0;
}

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