Save the image rendered by the OffscreenRendergraph channel

[WdsPjm]

I only want to save the image rendered by OffscreenRendergraph. How do I do this
I tried it by referring to vsgrendertotexture and vsgscreenshot, but it didn't work

auto context = vsg::Context::create(window->getOrCreateDevice());

// Framebuffer with attachments
VkExtent2D targetExtent{512, 512};
auto offscreenCamera = createCameraForScene(vsg_scene, targetExtent);
auto colorImage = vsg::ImageInfo::create();
auto depthImage = vsg::ImageInfo::create();
auto rtt_RenderGraph = createOffscreenRendergraph(*context, targetExtent, *colorImage, *depthImage);

auto rtt_view = vsg::View::create(offscreenCamera, vsg_scene);
rtt_RenderGraph->addChild(rtt_view);

// Planes geometry that uses the rendered scene as a texture map
vsg::ref_ptr<vsg::Node> planes = createPlanes(colorImage);
auto camera = createCameraForScene(planes, window->extent2D());
auto main_RenderGraph = vsg::createRenderGraphForView(window, camera, planes);

// add close handler to respond to the close window button and pressing escape
viewer->addEventHandler(vsg::CloseHandler::create(viewer));
nestedCommandGraph = true;
viewer->addEventHandler(vsg::Trackball::create(camera));
auto rtt_commandGraph = vsg::CommandGraph::create(window);

if (nestedCommandGraph)
{
    std::cout<<"Nested CommandGraph, with nested RTT CommandGraph as a child on the main CommandGraph. "<<std::endl;
  //  rtt_commandGraph = vsg::CommandGraph::create(window);
    rtt_commandGraph->submitOrder = -1; // render before the main_commandGraph
    rtt_commandGraph->addChild(rtt_RenderGraph);

    auto main_commandGraph = vsg::CommandGraph::create(window);
    main_commandGraph->addChild(main_RenderGraph);
   // main_commandGraph->addChild(rtt_commandGraph); // rtt_commandGraph nested within main CommandGraph

    viewer->assignRecordAndSubmitTaskAndPresentation({rtt_commandGraph});
}
else if (separateCommandGraph)
{
    std::cout<<"Seperate CommandGraph with RTT CommandGraph first, then main CommandGraph second."<<std::endl;
    auto rtt_commandGraph = vsg::CommandGraph::create(window);
    rtt_commandGraph->submitOrder = -1; // render before the main_commandGraph
    rtt_commandGraph->addChild(rtt_RenderGraph);

    auto main_commandGraph = vsg::CommandGraph::create(window);
    main_commandGraph->addChild(main_RenderGraph);

    viewer->assignRecordAndSubmitTaskAndPresentation({rtt_commandGraph, main_commandGraph});
}
else
{
    std::cout<<"Single CommandGraph containing by the RTT and main RenderGraphs"<<std::endl;
    // Place the offscreen RenderGraph before the plane geometry RenderGraph
    auto commandGraph = vsg::CommandGraph::create(window);
    commandGraph->addChild(rtt_RenderGraph);
    commandGraph->addChild(main_RenderGraph);

    viewer->assignRecordAndSubmitTaskAndPresentation({commandGraph});
}


auto event = vsg::Event::create_if(use_vkEvent, window->getOrCreateDevice()); // Vulkan creates VkEvent in an unsignalled state
// Add ScreenshotHandler to respond to keyboard and mouse events.
auto screenshotHandler = ScreenshotHandler::create(event, colorFilename, depthFilename, options);
viewer->addEventHandler(screenshotHandler);
if (event) rtt_commandGraph->addChild(vsg::SetEvent::create(event, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT));


viewer->compile();

if (multiThreading)
{
    std::cout<<"Enabled multi-threading"<<std::endl;
    viewer->setupThreading();
}

// rendering main loop
while (viewer->advanceToNextFrame())
{
    // pass any events into EventHandlers assigned to the Viewer
    viewer->handleEvents();
    viewer->update();
    viewer->recordAndSubmit();
    if (screenshotHandler->do_image_capture) screenshotHandler->screenshot_image(rtt_commandGraph->window);
    
    viewer->present();
}

[WdsPjm]

Just make the following changes in screenshot_image to save only images rendered by offscreenrender

auto physicalDevice = window->getPhysicalDevice();
// auto swapchain = window->getSwapchain();

    // get the colour buffer image of the previous rendered frame as the current frame hasn't been rendered yet.  The 1 in window->imageIndex(1) means image from 1 frame ago.
   
    auto sourceImage = offscreenImageInfo->imageView->image; //  window->imageView(window->imageIndex(1))->image;

    VkFormat sourceImageFormat = offscreenImageInfo->imageView->image->format; // swapchain->getImageFormat();
    VkFormat targetImageFormat = sourceImageFormat;

[robertosfield]

My brain is befuddled due to a cold so not a in place to go figure out stuff. Does the above reply mean you've solved the problem?

[WdsPjm]

I am very sorry to have wasted your valuable time. Yeah, I already took care of it.

[robertosfield]

I'll make your above reply as a answer then, you should be able to do this yourself too if you ever answer your own question :-)

[WdsPjm]

I'm sorry to hear that you have a cold. Wishing you a speedy recovery