CODEWITHSUNDEEP
renderingdirectx-11rendertarget
user9942393
user9942393

Reputation: 53

How can I overlay my UI render target onto the back buffer using DirectX 11?

I have two render targets, the back buffer and a UI render target where all 2d UI will be drawn.

I have used the graphics debugger to confirm that both render targets are being written to with the correct data, but I'm having trouble combining the two right at the end.

Question:

My world objects are drawn directly to the backbuffer so there is no problem displaying these, but how do I now overlay the UI render target OVER the backbuffer?

Desired effect:

enter image description here

Back buffer render target enter image description here

UI render target enter image description here

Upvotes: 2

Views: 1762

Answers (1)

Alex
Alex

Reputation: 1924

There's several ways to do this. The easiest is to render your UI elements to a texture that has both a RenderTargetView and a ShaderResourceView, then render the whole texture to the back buffer as a single quad in orthographic projection space. This effectively draws a 2D square containing your UI in screen space on the back buffer. It also has the benefit of allowing transparency.

You could also use the OutputMerger stage to blend the UI render target with the back buffer during rendering of the world geometry. You'd need to be careful how you set up your blend operations, as it could result in items being drawn over the UI, or blending inappropriately.

If your UI is not transparent, you could do the UI rendering first and mark the area under the UI in the stencil buffer, then do your world rendering while the stencil test is enabled. This would cause the GPU to ignore any pixels underneath the UI, and not send them to the pixel shader.

The above could also be modified to write the minimum depth value to the pixels within the UI render target, ensuring all geometry underneath it would fail the depth test. This modification would free up the stencil buffer for mirrors/shadows/etc.

The above all work for flat UIs drawn over the existing 3D world. To actually draw more complex UIs that appear to be a part of the world, you'll need to actually render the elements to 3D objects in the world space, or do complex projection operations to make it seem like they are.

Upvotes: 0

Related Questions