I'm pretty new to direct x, if you've seen my other posts, you probably know that. I'm trying to copy the middle section of the back buffer to a different surface and then copy that back to the top half of the back buffer. My plan later on is to do this twice, copying the back buffer to 2 different surfaces, then modifying those surfaces, and finally copying them back to the back buffer in a sort of splitscreen fashion (so that one surface copies to the top half of the back buffer, and the other surface copies to the bottom half of the back buffer).

Here's my code, which seems pretty sound to me:

        //rendering stuff
	m_lpDX->m_lpDevice->EndScene();
        IDirect3DSurface9 * frame1 = NULL;
        IDirect3DSurface9 * pBackBuffer = NULL;
        RECT r1;
        SetRect(&r1, GetHeight()/4, 0, GetWidth(), ((GetHeight()*3)/4)-1);
        
        m_lpDX->m_lpDevice->GetBackBuffer( 0, 0, D3DBACKBUFFER_TYPE_MONO, &pBackBuffer );
        m_lpDX->m_lpDevice->CreateOffscreenPlainSurface(GetWidth(),GetHeight()/2,D3DFMT_X8R8G8B8,D3DPOOL_DEFAULT,&frame1,NULL);// - CAT
        D3DLOCKED_RECT frame1Lock;
        D3DLOCKED_RECT pBackBufferLock;
        frame1->LockRect(&frame1Lock,NULL,NULL);
        pBackBuffer->LockRect(&pBackBufferLock,NULL,NULL);

        m_lpDX->m_lpDevice->UpdateSurface(pBackBuffer,&r1,frame1,NULL);
        r1.top = 0;
        r1.left = 0;
        m_lpDX->m_lpDevice->UpdateSurface(frame1,&r1,pBackBuffer,NULL);
        frame1->UnlockRect();
        pBackBuffer->UnlockRect();
        frame1->Release();
        pBackBuffer->Release();

Trouble is, nothing changes. The regular back buffer still shows. Does anyone have any trouble shooting ideas?

Check all HRESULT returned by API calls with the SUCCEEDED/FAILED macroes for failure.

For more information: Direct3D Programming Tip #5: Use The Debug Runtime.

From a quick glance: According to docs you can't use UpdateSurface when the surfaces are locked (why would you anyway, unless you want to copy manually).

OKay so let me get this straight before I get started.

The process should look like this:

		m_lpDX->m_lpDevice->EndScene();
        IDirect3DSurface9 * frame1 = NULL;
        IDirect3DSurface9 * frame2 = NULL;
        IDirect3DSurface9 * pBackBuffer = NULL;
        IDirect3DSurface9 * pActualBackBuffer = NULL;

        RECT r1;
        SetRect(&r1, 0, GetHeight()/4, GetWidth(), ((GetHeight()*3)/4));

        //get back buffer and initialize frame surfaces
        m_lpDX->m_lpDevice->GetBackBuffer( 0, 0, D3DBACKBUFFER_TYPE_MONO, &pBackBuffer );
        m_lpDX->m_lpDevice->GetRenderTargetData(pBackBuffer,pActualBackBuffer);
        m_lpDX->m_lpDevice->CreateOffscreenPlainSurface(GetWidth(),GetHeight()/2,D3DFMT_/*format matching back buffer*/,D3DPOOL_DEFAULT,&frame1,NULL);// - CAT
        m_lpDX->m_lpDevice->CreateOffscreenPlainSurface(GetWidth(),GetHeight()/2,D3DFMT_/*format matching back buffer*/,D3DPOOL_DEFAULT,&frame2,NULL);// - CAT

//copy middle of back buffer to the two surfaces
        m_lpDX->m_lpDevice->StretchRect(pActualBackBuffer,&r1,frame1,NULL,D3DTEXF_NONE);
        m_lpDX->m_lpDevice->StretchRect(pActualBackBuffer,&r1,frame2,NULL,D3DTEXF_NONE);

//some operations would go here later to modify the surfaces for a left and right eye view

//copy frame surfaces back to the back buffer to be presented later.
        RECT d1;
        SetRect(&d1, 0, 0, GetWidth(), GetHeight()/2);
        m_lpDX->m_lpDevice->StretchRect(frame1,NULL,pActualBackBuffer,&d1,D3DTEXF_NONE);
        RECT d2;
        SetRect(&d2, 0, GetHeight()/2, GetWidth(), GetHeight());
        m_lpDX->m_lpDevice->StretchRect(frame2,NULL,pActualBackBuffer,&d2,D3DTEXF_NONE);

//release pointers
        frame1->Release();
        frame2->Release();
        pBackBuffer->Release();
        pActualBackBuffer->Release();

You'll notice that I did not check for the HResults, that is because I have a different question having to do with those before I write them in.

So I checked out the article that Unbird linked. I opened up the directx control panel and set it up for debug mode, however nothing came out. After googling I found that I needed to declare #define D3D_DEBUG_INFO so I did that, in this fashion:

//#ifdef _DEBUG
    #define D3D_DEBUG_INFO  // declare this before including d3d9.h
//#endif

#include <d3d9.h>
#include <d3dx9.h>

I'm not really sure where I'm supposed to retrieve the debug info though. Alternatively, I would settle for just being able to output some info, like with println(); but the program I am altering simply becomes a plugin for another piece of software. Therefore, i don't know where to find the output. I don't have a lot of experience with the command line, but I am wondering "Is there something there I could do?"

EDIT: This has to do with my question about HRESULT, which is essentially, "How can I make some custom text output that I can reference, while in this plugin?"

Lastly, I just wanted to say, I'm a senior college student with no prior graphics programming experience. Is this project too demanding for someone from my position? Further, do you have any general advice for someone in my position?

With regard to graphics programming experience - you're getting some now, huh?!

I'm not exactly sure what the inflection is here. Are you saying this is too early for a programmer to learn graphics programming or too late, or are you stated that I am currently getting experience? I don't mean to sound condescending I'm just wondering what you meant and where that means I am now (I.E. ahead of the curve, behind, doesn't matter where)

EDIT: an alternative, depending on how much time you have to work on your project - download Visual Studio (you can get a free version, maybe even a full-blown version being a college student). Create a version of your plugin as a standalone, test it thoroughly there and create another version as the plugin. Actually, you may save time overall by doing that. At worst, you appear to be interested in that type of programming so get into Visual Studio.

I have been using visual c++ 2008 express edition. It was recommended by my client, because it can compile the byte code within 1KB. I do have Visual studio somewhere on this computer and I think that it is a full version (because I'm a student). I guess I should be giving that a try? I will try it.

This has to do with my question about HRESULT, which is essentially, "How can I make some custom text output that I can reference, while in this plugin?"

If the app has a console window (which it should, if it doesn't), std::cout ( or printf() ) would work. Or launch the app from a cmd window. Otherwise, take a look at OutputDebugString(). The latter outputs c-strings, which requires you to format your output string if you want to output numbers. Again, if you're not launching it from Visual Studio, you'll have to find a debug message monitor like debugview.

For clarity's sake let me say that back as I understood it to make sure I have it right. If I use Visual Studio it should give me a debug message monitor. How do I access this monitor? Do I need to do anything special with my .dll file? I really have no idea how to test it, except to build it and launch the main app, and then use the plugin to see what happens. An alternative quicker or more custom-message-friendly testing method would be showered with my love.

EDIT: What did you think of my process I outlined in my previous post? Did it look appropriate?

You can implement split screen without doing any copying of render targets.

The way you to that is to use viewports - the default viewport you get when you set a render target is a full size one, but you can change that to cover a different portion of the render target to do things like split screen.

The main advantage of that approach is that it will perform better than copying. Especially if your copies go back and forth to system memory instead of staying on the GPU.

If you really need to copy bits of render target around, I'd suggest using StretchRect() with the help of GetSurfaceLevel(). That will avoid the copying to and from system memory.

render targets are a prety plentyfull resources, don't play with them too bad

(it is a writing of gpu station, forget about storing them over cpu, issuing back driver ordered commands)

in stead, only thing you can do-- has to be issued to gpu toward gpu memory objects.