How to know the frame is finish rendering after calling render with OpenGL backend？

[August1996]

the setFrameCompletedCallback api is only for Metal backend.

[Mahmuttalemdar]

// Create your own callback
using RenderCallback = std::function<void(uint8_t*, size_t, uint32_t, uint32_t)>;

// Create your own callback object
RenderCallback renderCallback;
std::vector<uint8_t> streamBuffer;

void Render() 
{    
    // Begin rendering frame
    if (renderer->beginFrame(swapChain)) {
        // Render the scene
        renderer->render(view);
        // End rendering frame
        renderer->endFrame();
        
        // If rendering streaming is enabled, perform post-render operations
        if (Config.RenderStreaming == true) {
            PostRender();
        }
    }
}

void PostRender()
 {
    // Create a PixelBufferDescriptor for reading pixels
    filament::backend::PixelBufferDescriptor pixelBufferDescriptor(streamBuffer.data(), streamBuffer.size(),
        filament::backend::PixelDataFormat::RGBA,
        filament::backend::PixelDataType::UBYTE);
    
    // Read pixels from the renderer into the streamBuffer
    renderer->readPixels(0, 0, m_width, m_height, std::move(pixelBufferDescriptor));
    // Flush and wait for the rendering engine
    engine->flushAndWait();
    
    // If a render callback is set, invoke it with the pixel data and dimensions
    if (renderCallback) {
        renderCallback(streamBuffer.data(), streamBuffer.size(), m_width, m_height);
    }
}

// Last step
// Finally, you can access the callback from anywhere you want.

[August1996]

thanks, maybe the flushAndWait api is a good choice.