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Editorial Team
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Asked: 2026-05-13T18:12:17+00:00

I am trying to enable AA in a D3D9 application, but am not sure

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I am trying to enable AA in a D3D9 application, but am not sure how to set up the surfaces correctly. So far, I have:

IDirect3DDevice9* m_pd3dDevice;
IDirect3DSurface9* screen;
IDirect3DSurface9* msaasurf;
D3DPRESENT_PARAMETERS m_presentationParameters;

Initialization:

m_presentationParameters.Windowed = TRUE;
m_presentationParameters.SwapEffect = D3DSWAPEFFECT_DISCARD;
m_presentationParameters.MultiSampleType = D3DMULTISAMPLE_2_SAMPLES;
m_presentationParameters.MultiSampleQuality = 0;
m_presentationParameters.BackBufferFormat = D3DFMT_UNKNOWN;
m_presentationParameters.EnableAutoDepthStencil = TRUE;
m_presentationParameters.AutoDepthStencilFormat = D3DFMT_D16;
m_presentationParameters.PresentationInterval = D3DPRESENT_INTERVAL_IMMEDIATE;

// create d3d device
m_pD3D->CreateDevice(
  D3DADAPTER_DEFAULT, 
  D3DDEVTYPE_HAL, 
  hWnd,
  D3DCREATE_HARDWARE_VERTEXPROCESSING,
  &m_presentationParameters, &m_pd3dDevice 
)


// save screen surface
m_pd3dDevice->GetRenderTarget(0, &screen);
D3DSURFACE_DESC desc;
screen->GetDesc(&desc);

// Create multisample render target
m_pd3dDevice->CreateRenderTarget(
    800, 600, 
    D3DFMT_A8R8G8B8,
    desc.MultiSampleType, desc.MultiSampleQuality,
    false,
    &msaasurf,
    NULL
  );

And then, for each frame:

// render to multisample surface
m_pd3dDevice->SetRenderTarget(0, msaasurf);

m_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB( 0, 0, 0 ), 1.0f, 0 );
m_pd3dDevice->BeginScene();

// render stuff here

m_pd3dDevice->EndScene();

m_pd3dDevice->SetRenderTarget(0, screen);

// get back buffer
IDirect3DSurface9* backBuffer = NULL;
m_pd3dDevice->GetBackBuffer(0, 0, D3DBACKBUFFER_TYPE_MONO, &backBuffer);

// copy rendertarget to backbuffer
m_pd3dDevice->StretchRect(msaasurf, NULL, backBuffer, NULL, D3DTEXF_NONE);
backBuffer->Release();

// Present the backbuffer contents to the display
m_pd3dDevice->Present(NULL, NULL, NULL, NULL);

However, nothing is appearing on my screen (all black). No errors are occuring (I check the return value of all d3d calls). What am I doing wrong?

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1 Answer

  1. Editorial Team

    You don’t need the extra surface, you can render directly to the multisampled backbuffer. For me, the only reason to use StretchRect() like this is to get a non-multisampled copy of the scene for use with postprocessing (because multisampled render targets are bad textures, so you need the scene data in a resolved texture). If you want to do this, you don’t need to specify multisampling for the backbuffer. A multisampled render target to render the scene to is sufficient then.

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