Reading and writing an anti-aliased texture in Direct3D9

Question

I'm slightly confused about textures versus surfaces in Direct3D9. Now, it seems fairly simple that you can only read from a texture and only write to a surface, and when you create a texture then you can get surfaces to set as render targets from it.

What I don't quite get is the CreateTexture function. It's CreateRenderTarget equivalent for a surface which is only rendered to and never read has the options of anti-aliasing parameters, whereas CreateTexture doesn't, even though you can explicitly use it to create render targets.

Does that mean that it is impossible to create an intermediate texture for e.g. shadow mapping which has anti-aliasing?

Answer 1

I'm fairly sure you cannot read an MSAA (antialiased) render target directly as a texture in D3D9. (You can do that in D3D10-11, I believe). In D3D9, you must "resolve" an MSAA render target by copying it to a non-MSAA render target using StretchRect. This results in a plain image with the antialiasing baked in, which you can then use as a texture.