I am trying to implement a PostProcessing manager in my 3D engine, but I'm failing. I keep getting the first texture just slapped over the top of everything else. I'm just creating a new RenderTarget2D using the GraphicsDevice's Viewport in order to set the Width, Height etc. but it just overwrites everything.
Does anyone have any ideas? My understanding of the RenderTarget2D was that it took a "snapshot" of the screen and then I can redraw that later.
Ensure that you aren't setting your RenderTarget2D more than once, also use the GraphicsDevice's viewport to create your RenderTarget2D