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Using breakpoints, I'm trying to figure out the working of a complex app which uses DirectX buffers.
I see many places where the Blt command draws to the back buffer/surface, and I need to know what exactly it is drawing at that point in the code.

Unfortunately, I'm able to see what was drawn only when the entire frame is drawn and the buffers are flipped.

Isn't there a way to see the back buffer/surface while it is being drawn? Before it gets flipped?

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You can use PIX for Windows to debug rendering issues or performance bottlenecks in the GPU. PIX is a profiler that will give you very detailed info on what is happening at each step while rendering.

So it will allow you to see what is rendered in the back buffer at each Direct3D call. You can also select a given pixel in the final image and see what happened in the history of that pixel (shaders applied to it for example).

Here are a couple of tutorials:

http://blogs.msdn.com/b/manders/archive/2006/12/15/a-painless-introduction-to-pix-for-windows.aspx

http://www.garagegames.com/community/blogs/view/14251

http://www.youtube.com/watch?v=-3PISvNTeB0&feature=player_embedded

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Tried using PIX, but it waits for my application to exit and only then shows the profiled information (couldn't find the backbuffer info too). Isn't it possible to view the back buffer while my application is running? (couldn't go thru the youtube video coz youtube is blocked on this server)
hey Nav. PIX will indeed measure your application while it is executing and will show you the profiled information at the end. It cannot show you the information of what is happening in realtime because it is too much information. You can select to only capture a few frames with F12 though.
By the way in general (and in Direc3D) every draw call (such as SetRenderState, SetVertexShader, etc) happens in the BackBuffer by default. It is only displayed to the main frame when you see a IDirect3DDevice9::Present function call. So PIX is showing you what is happening in the back buffer.
Thanks, but what I really wanted to see was the drawing being performed on the back buffer as and when it happens. So seems like there's no tool which can help with that.

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