Apply bloom effect to RenderTarget without affecting UI

Question

I'm currently rendering my whole game to a RenderTarget in order to stretch the scene to any resolution. I also have a bloom effect rendered with the scene. I'm now working on the UI part of the game, the problem is, I don't want the bloom to affect the UI elements.

So in order to not have the bloom apply to the UI, I need to draw it after the base.Draw(gameTime); call. It works, the UI is not affected by the bloom but is also rendered outside of the render target which isn't making it responsive for every resolution.

How can I incorporate the UI inside the render target but without having it affected by the bloom component?

This is the Draw method code:

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.SetRenderTarget(_renderTarget);
        GraphicsDevice.Clear(Color.Black);

        Bloom.BeginDraw();

        _currentState.Draw(gameTime, _spriteBatch);
        GraphicsDevice.SetRenderTarget(null);
        _spriteBatch.Begin(blendState: BlendState.AlphaBlend);
        _spriteBatch.Draw(_renderTarget, new Rectangle(0, 0, GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height), Color.White);
        //_spriteBatch.Draw(texture, new Rectangle(50, 50, 500, 200), new Color(Color.Black, 0.7f));
        _spriteBatch.End();

        base.Draw(gameTime);

        _currentState.PostDraw(gameTime, _spriteBatch);
    }

Answer 1

I've figured it out thanks to the Monogame community discord. For anyone who will come across this issue - What I did in the end is render the "bloomed scene" to the main render target of the game (instead of the backbuffer as it was until now) and then render both the main render target and the UI elements to a new secondary render target which gets drawn to the backbuffer. So the solution was effectively using 2 render targets which have the same size and are using the same GraphicsDevice. Works like a charm.