HI Zheng, I am away from my dev machine so not in a position to look up the implementation side for subload callback to double check your code.
In general though I wouldn't recommend having the draw traversal doing a read from a device as this is very likely to cause a frame drop. The standard way to tackle this type of problem is to have a back ground thread read from the device copying the data an osg::Image, after copying calling dirty() on the image. This osg::Image would also be attached to the osg::Texture in the scene graph, but there is no need to implement a subload callback as the Texture::apply() checks the Image modifiedCount() and automatically subloads for you. The video plugins like ffmpeg, quicktime and directshow ones implement this approach. Robert. On 23 March 2016 at 15:10, Zheng Li <[email protected]> wrote: > Hi, > > I wrote a "SubloadCallback" derived class and attach it to a texture2D > object to update image dynamically,but unfortunately the texture image can > not be updated,the texture always show a piece of white;below is my > code,what wrong happened to it? > > void main() > { > // the class to update texture image dynamically; > class UpdateTextureCallback : public > osg::Texture2D::SubloadCallback > { > public: > osg::ref_ptr<osg::Image> _image; > SIZE m_szVideo; > > public: > UpdateTextureCallback(int vwidth,int vheight) > { > m_szVideo.cx = vwidth; > m_szVideo.cy = vheight; > _image = osgDB::readImageFile("C:\\test.jpg"); > assert(_image->valid()); > _image->scaleImage(vwidth,vheight,_image->r()); > }; > > virtual ~UpdateTextureCallback() > { > _image = NULL; > }; > > virtual void load(const osg::Texture2D& > texture,osg::State& state) const > { > > glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,m_szVideo.cx,m_szVideo.cy,0,GL_BGRA_EXT,GL_UNSIGNED_BYTE,NULL); > }; > > virtual void subload(const osg::Texture2D& > texture,osg::State& state) const > { > readImageFromDevice(_image); > > glTexSubImage2D(GL_TEXTURE_2D,0,0,0,_image->s(),_image->t(),_image->getPixelFormat(),_image->getDataType(),_image->getDataPointer()); > }; > }; > > const int VideoWidth = 3840; > const int VideoHeight = 2160; > osg::ref_ptr<osg::Texture2D> texVideo = new osg::Texture2D(); > texVideo->setResizeNonPowerOfTwoHint(false); > texVideo->setTextureSize(VideoWidth,VideoHeight); > texVideo->setInternalFormat(GL_RGBA); > texVideo->setSubloadCallback(new > UpdateTextureCallback(VideoWidth,VideoHeight)); > > osg::ref_ptr<osg::Geode> quad = new osg::Geode(); > quad->addDrawable(createDrawable_Quad()); > > quad->getOrCreateStateSet()->setTextureAttributeAndModes(0,texVideo.get()); > > osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer(); > viewer->realize(); > viewer->getCamera()->setAllowEventFocus(false); > viewer->getCamera()->setProjectionMatrixAsOrtho2D(0,1,0,1); > viewer->getCamera()->setViewMatrix(osg::Matrix::identity()); > viewer->setSceneData( quad ); > viewer->run(); > } > > osg::Geometry * createDrawable_Quad(float alpha=1.0f) > { > osg::ref_ptr<osg::Vec2Array> vertices = new osg::Vec2Array; > vertices->push_back( osg::Vec2(0,0) ); > vertices->push_back( osg::Vec2(0,1) ); > vertices->push_back( osg::Vec2(1,1) ); > vertices->push_back( osg::Vec2(1,0) ); > > osg::ref_ptr<osg::Vec2Array> texcoords = new osg::Vec2Array; > texcoords->push_back( osg::Vec2(0.0f, 0.0f) ); > texcoords->push_back( osg::Vec2(0.0f, 1.0f) ); > texcoords->push_back( osg::Vec2(1.0f, 1.0f) ); > texcoords->push_back( osg::Vec2(1.0f, 0.0f) ); > > osg::ref_ptr<osg::Vec4Array> colors = new osg::Vec4Array(); > colors->push_back(osg::Vec4(1.0f,1.0f,1.0f,alpha)); > > osg::ref_ptr<osg::Geometry> quad = new osg::Geometry; > quad->setVertexArray( vertices.get() ); > quad->setColorArray(colors.get()); > quad->setColorBinding( osg::Geometry::BIND_OVERALL ); > quad->setTexCoordArray( 0, texcoords.get() ); > quad->addPrimitiveSet( new osg::DrawArrays(GL_QUADS, 0, 4) ); > return quad.release(); > } > > > Thank you! > > Cheers, > Zheng > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=66611#66611 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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