Z-buffer creation error

quote:

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Original post by Kjell Andersson

The problem is that my creation now fails. What have I done wrong?

Here is the code I use now that does not work:

DDSURFACEDESC2 ddsd;
memset(&ddsd, 0, sizeof(ddsd));
ddsd.dwSize = sizeof(ddsd);
ddsd.dwFlags = DDSD_CAPS / DDSD_HEIGHT / DDSD_WIDTH / DDSD_PIXELFORMAT;
ddsd.ddsCaps.dwCaps = DDSCAPS_ZBUFFER;
ddsd.dwHeight = 128;
ddsd.dwWidth = 128;
ddsd.ddpfPixelFormat.dwSize = sizeof(ddsd.ddpfPixelFormat);
ddsd.ddpfPixelFormat.dwFlags = DDPF_ZBUFFER;
ddsd.ddpfPixelFormat.dwZBufferBitDepth = 16;
d3dapp->m_pDD->CreateSurface(&ddsd, &m_lpDDSz, NULL);

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Hi Kjell,

First I think you have a typo in the ddsd.dwFlags line. It should read

ddsd.dwFlags = DDSD_CAPS / DDSD_HEIGHT / DDSD_WIDTH / DDSD_PIXELFORMAT;

If you make this change the call fails but this time because the ddsd.ddpfPixelFormat structure is wrong. The best to accurately fill this out (in fact this is what D3D recommends, and I do) is prior to creating your ZBuffer you enumerate the card''s zbuffer formats.

Here is some sample code

DDPIXELFORMAT g_MyZBufferPF;

// This is a very simple callback - we will just use the
// first 16-bit z-buffer format that we find.
HRESULT CALLBACK EnumZBufferPFCallback( LPDDPIXELFORMAT lpDDPixFmt , LPVOID lpContext )
{
if (lpDDPixFmt->dwZBufferBitDepth == 16)
{
g_MyZBufferPF = *lpDDPixFmt;
return D3DENUMRET_CANCEL;
}

return D3DENUMRET_OK;
}

...

// Z-Buffer creation code

// Enumerate Z-Buffer formats
// Substitute the correct D3D GUID in, e.g. if you
// don''t have a TnL device then you would want to use
// IID_IDirect3DHALDevice.

HRESULT hr;
hr = m_pD3D7->EnumZBufferFormats( IID_IDirect3DTnLHalDevice , EnumZBufferPFCallback );
if (FAILED( hr ))
// Error: do something

// And then your code with a slight modification.
DDSURFACEDESC2 ddsd;
memset(&ddsd, 0, sizeof(ddsd));
ddsd.dwSize = sizeof(ddsd);
ddsd.dwFlags = DDSD_CAPS / DDSD_HEIGHT / DDSD_WIDTH / DDSD_PIXELFORMAT;
ddsd.ddsCaps.dwCaps = DDSCAPS_ZBUFFER;
ddsd.dwHeight = 128;
ddsd.dwWidth = 128;

Here is the change, we just copy our z-buffer pixel format
of choice into the ddsd.ddpfPixelFormat field...

ddsd.ddpfPixelFormat = g_MyZBufferPF;
d3dapp->m_pDD->CreateSurface(&ddsd, &m_lpDDSz, NULL);

I have tested this code on my GeForce it works absolutely fine.

HTH

Chris

Chris Killpack : ckillpack@eaeurope.com
Technology Group : Bullfrog Productions Ltd