如何在openscenegraph上运行时更改背景

Question

我尝试在查看器上添加一个3d对象并动态更改背景。我使用opencv VideoCapture捕获网络摄像头。

我做了以下步骤：

1. 打开视频捕获并获取框架
2. 创建openscenegraph root
3. 将子项添加到root（从.osg文件3d对象中读取）
4. 为背景
创建texture2d对象
5. 设置背景图片
6. 创建相机以查看背景
7. 将相机添加到根
8. 设置查看者的数据（viewer.setScenedat(root)）

9. 运行viewer.run()

   这些步骤将第一帧添加为背景，并将3d对象添加到场景中。但我无法改变每一帧的背景。我该怎么做？

代码：

cv::VideoCapture cap(0);  
cv::Mat frame;

if(!cap.isOpened())  
{
    std::cout << "Webcam cannot open!\n";
    return;
}  

osgViewer::Viewer viewer;
osg::ref_ptr<osg::Group> root = new osg::Group();
osg::ref_ptr<osg::Texture2D> bg = new osg::Texture2D();

root->addChild(osgDB::readNodeFile("object.osg"));
bg->setFilter(osg::Texture::FilterParameter::MIN_FILTER, osg::Texture::FilterMode::LINEAR);
bg->setFilter(osg::Texture::FilterParameter::MAG_FILTER, osg::Texture::FilterMode::LINEAR);    
bg->setDataVariance(osg::Object::DYNAMIC);

cap >> frame;
osg::ref_ptr<osg::Image> osgImage = new osg::Image;
osgImage->setImage(frame.cols, frame.rows, 3,
    GL_RGB, GL_RGB, GL_UNSIGNED_BYTE,
    (uchar*)(frame.data),
    osg::Image::AllocationMode::NO_DELETE, 1);
bg->setImage(osgImage);

osg::ref_ptr<osg::Camera> bg_cam = new osg::Camera();
bg_cam->setProjectionMatrixAsOrtho2D(-0.5, 0.5, -0.5, 0.5);
bg_cam->setViewMatrixAsLookAt(
    osg::Vec3(0.5, 0.5, -1.0),
    osg::Vec3(0.5, 0.5, 0.0),
    osg::Vec3(0.0, -1.0, 0.0)
    );
bg_cam->setRenderOrder(osg::Camera::PRE_RENDER);
bg_cam->setReferenceFrame(osg::Camera::ABSOLUTE_RF);
bg_cam->addChild(initializeBackground(bg));
root->addChild(bg_cam);

viewer.setSceneData(root);
viewer.getCamera()->setProjectionMatrixAsPerspective(
    40., 1., 1., 100.);
viewer.getCamera()->setClearMask(GL_DEPTH_BUFFER_BIT);
viewer.getCamera()->setClearColor(osg::Vec4(1.0, 0.0, 0.0, 1.0));

viewer.run();

Answer 1

viewer.getCamera()->setClearMask(GL_DEPTH_BUFFER_BIT);
viewer.getCamera()->setClearColor(osg::Vec4(1.0, 0.0, 0.0, 1.0));
 bg->setDataVariance(osg::Object::DYNAMIC);
viewer.realize();  // set up windows and associated threads. 

while(!viewer.done())
{
    cap >> frame;     

    osg::ref_ptr<osg::Image> osgImage = new osg::Image;
    osgImage->setImage(frame.cols, frame.rows, 3,
        GL_RGB, GL_BGR, GL_UNSIGNED_BYTE,
        (uchar*)(frame.data),
        osg::Image::AllocationMode::NO_DELETE, 1);
    bg->setImage(osgImage);

    viewer.frame();
}   

此代码动态更改背景。