4.6 Debugging Direct3D Applications

4.6 Debugging Direct3D Applications

In order to shorten the code and minimize distractions, we omit most error handling in this book. However, we do implement a macro to check the HRESULT return codes returned by many Direct3D functions. Our macro is defined as follows in d3dUtil.h:

 

#if defined(DEBUG) | defined(_DEBUG)
    #ifndef HR
    #define HR(x)                                                \
    {                                                            \
        HRESULT hr = (x);                                        \
        if(FAILED(hr))                                           \
        {                                                        \
            DXTrace(__FILE__, (DWORD)__LINE__, hr, L#x, true);   \
        }                                                        \
    }
    #endif
 #else
    #ifndef HR
    #define HR(x) (x)
    #endif
 #endif

  

If the returned function’s return code indicates failure, then we pass the return code into the DXTrace function (#include <dxerr.h>) and link dxerr.lib:

HRESULT WINAPI DXTraceW(const char* strFile, DWORD dwLine,
    HRESULT hr, const WCHAR* strMsg, BOOL bPopMsgBox);

 

This function displays a nice message box indicating the file and line number where the error occurred, as well as a textual description of the error and the name of the function that generated the error; Figure 4.10 shows an example. Note that if you specify false for the last parameter of DXTrace, then instead of a message box, the debug info will be output to the Visual C++ output window. Observe that the macro HR does nothing if we are not in debug mode. Also, HR must be a macro and not a function; otherwise __FILE__ and __LINE__ would refer to the file and line of the function implementation instead of the file and line where the function HR was called.

 
Figure 4.10: The message box displayed by the DXTrace function if a Direct3D function returns an error.

Now we just use this macro to surround a Direct3D function that returns an HRESULT as this example shows:  

HR(D3DX10CreateShaderResourceViewFromFile(md3dDevice,
      L"grass.dds", 0, 0, &mGrassTexRV, 0 ));

This works well for debugging our demos, but a real application should handle errors more robustly.

Note The L#x turns the HR macro’s argument token into a Unicode string. In this way, we can output to the message box the function call that caused the error.