[osg-users] Resizing FBO camera while rendering

[Robert Osfield]

Hi Rômulo,

I didn't spot any code you posted that handles resizing, did I miss it?

Robert.
On Tue, 2 Oct 2018 at 08:10, Rômulo Cerqueira
<romulogcerqueira at gmail.com> wrote:
>
> Hi,
>
> I have rendered a FBO camera to image by using a callback (as seen in the code below), however some OpenGL warnings/erros are raised when I resize at runtime by setupViewer() method. I debugged the code by using
>
>
> Code:
> export OSG_GL_ERROR_CHECKING=ON
>
>
>
> and got the following error:
>
>
> Code:
> Warning: detected OpenGL error 'invalid operation' after applying attribute Viewport 0x7fb35406e500
>
>
>
> How can I properly do the resizing of my FBO camera?
>
>
>
> Code:
> // create a RTT (render to texture) camera
> osg::Camera *ImageViewerCaptureTool::createRTTCamera(osg::Camera* cam, osg::Camera::BufferComponent buffer, osg::Texture2D *tex, osg::GraphicsContext *gfxc)
> {
>     osg::ref_ptr<osg::Camera> camera = cam;
>     camera->setClearColor(osg::Vec4(0, 0, 0, 1));
>     camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
>     camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
>     camera->setRenderOrder(osg::Camera::PRE_RENDER, 0);
>     camera->setViewport(0, 0, tex->getTextureWidth(), tex->getTextureHeight());
>     camera->setGraphicsContext(gfxc);
>     camera->setDrawBuffer(GL_FRONT);
>     camera->setComputeNearFarMode(osg::CullSettings::DO_NOT_COMPUTE_NEAR_FAR);
>     camera->attach(buffer, tex);
>     return camera.release();
> }
>
> // create float textures to be rendered in FBO
> osg::Texture2D* ImageViewerCaptureTool::createFloatTexture(uint width, uint height)
> {
>     osg::ref_ptr<osg::Texture2D> tex2D = new osg::Texture2D;
>     tex2D->setTextureSize( width, height );
>     tex2D->setInternalFormat( GL_RGB32F_ARB );
>     tex2D->setSourceFormat( GL_RGBA );
>     tex2D->setSourceType( GL_FLOAT );
>     tex2D->setResizeNonPowerOfTwoHint( false );
>     tex2D->setFilter( osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR );
>     tex2D->setFilter( osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR );
>     return tex2D.release();
> }
>
> void ImageViewerCaptureTool::setupViewer(uint width, uint height, double fovY)
> {
>     // set graphics contexts
>     osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
>     traits->x = 0;
>     traits->y = 0;
>     traits->width = width;
>     traits->height = height;
>     traits->pbuffer = true;
>     traits->readDISPLAY();
>     osg::ref_ptr<osg::GraphicsContext> gfxc = osg::GraphicsContext::createGraphicsContext(traits.get());
>
>     // set the main camera
>     _viewer = new osgViewer::Viewer;
>     osg::ref_ptr<osg::Texture2D> tex = createFloatTexture(width, height);
>     osg::ref_ptr<osg::Camera> cam = createRTTCamera(_viewer->getCamera(), osg::Camera::COLOR_BUFFER0, tex, gfxc);
>     cam->setProjectionMatrixAsPerspective(osg::RadiansToDegrees(fovY), (width * 1.0 / height), 0.1, 1000);
>
>     // render texture to image
>     _capture = new WindowCaptureScreen(gfxc, tex);
>     cam->setFinalDrawCallback(_capture);
> }
>
> osg::ref_ptr<osg::Image> ImageViewerCaptureTool::grabImage(osg::ref_ptr<osg::Node> node)
> {
>     // set the current node
>     _viewer->setSceneData(node);
>
>     // if the view matrix is invalid (NaN), use the identity
>     if (_viewer->getCamera()->getViewMatrix().isNaN())
>         _viewer->getCamera()->setViewMatrix(osg::Matrixd::identity());
>
>     // grab the current frame
>     _viewer->frame();
>     return _capture->captureImage();
> }
>
> ////////////////////////////////
> ////WindowCaptureScreen METHODS
> ////////////////////////////////
>
> WindowCaptureScreen::WindowCaptureScreen(osg::ref_ptr<osg::GraphicsContext> gfxc, osg::Texture2D* tex) {
>     _mutex = new OpenThreads::Mutex();
>     _condition = new OpenThreads::Condition();
>     _image = new osg::Image();
>
>     // checks the GraficContext from the camera viewer
>     if (gfxc->getTraits()) {
>         _tex = tex;
>         int width = gfxc->getTraits()->width;
>         int height = gfxc->getTraits()->height;
>         _image->allocateImage(width, height, 1, GL_RGBA, GL_FLOAT);
>     }
> }
>
> WindowCaptureScreen::~WindowCaptureScreen() {
>     delete (_condition);
>     delete (_mutex);
> }
>
> osg::ref_ptr<osg::Image> WindowCaptureScreen::captureImage() {
>     //wait to finish the capture image in call back
>     _condition->wait(_mutex);
>     return _image;
> }
>
> void WindowCaptureScreen::operator ()(osg::RenderInfo& renderInfo) const {
>     osg::ref_ptr<osg::GraphicsContext> gfxc = renderInfo.getState()->getGraphicsContext();
>
>     if (gfxc->getTraits()) {
>         _mutex->lock();
>
>         // read the color buffer as 32-bit floating point
>         renderInfo.getState()->applyTextureAttribute(0, _tex);
>         _image->readImageFromCurrentTexture(renderInfo.getContextID(), true, GL_FLOAT);
>
>         // grants the access to image
>         _condition->signal();
>         _mutex->unlock();
>     }
> }
>
>
>
> ...
>
> Thanks in advance,
>
> Cheers,
> Rômulo
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=75005#75005
>
>
>
>
>
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