DX: Surfaces

Does anyone have any clue why I am failing to lock this surface?

Code:

---

DDSURFACEDESC2 ddsd;

// this should lock the entire region...
if(FAILED(_lpPrimarySurface->Lock(NULL, &ddsd, DDLOCK_SURFACEMEMORYPTR | DDLOCK_WAIT, NULL)))
{
        DisplayError("Failed to Lock Surface.");
}

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Have you initialized the surface descriptor? I think you must always zero those structs out and set dwSize to the correct value, even if you only want to retrieve information.

Code:

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DDSURFACEDESC2 ddsd;
ZeroMemory(&ddsd, sizeof(DDSURFACEDESC2));
ddsd.dwSize = sizeof(DDSURFACEDESC2);

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BTW, this is a handy macro for DirectDraw programming:

Code:

---

#define DD_INITSTRUCT(s) \
  ZeroMemory(&(s), sizeof((s)));\
  (s).dwSize = sizeof((s));

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or in C++ (only MSVC++7, it won't work properly for 6 or older Borlands):

Code:

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template<typename T>
inline void DD_INITSTRUCT(T &s) {
  ::ZeroMemory(&s, sizeof(T));
  s.dwSize = sizeof(T);
}

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Yes, you're exactly right...when I removed it from my testing function which included the creation of the surface I had already done that, it stopped functioning. Nice call :-)