Using the D3DCompiler DLL with older DX9 SDKs via dynamic linking

If you want to compile shaders at runtime without D3DX, you may want to use the D3DCompiler_xx.dll.

Here is an example of how to dynamically load the D3DCompiler_xx.dll under DX9 without requiring a newer DXSDK installation which includes the complete D3D10/11 headers/libraries.

This approach has the added benefit that it works with the mingw compiler / QtCreator as well.

First we declare some required COM interfaces, D3D structures and the D3DCompile() function prototype (ofcourse you can add more functions like D3DCompileFromFile, etc. if needed):

#ifndef __ID3D10Blob_FWD_DEFINED__
#define __ID3D10Blob_FWD_DEFINED__
typedef interface ID3D10Blob ID3D10Blob;
#endif

#define D3DCOMPILER_DLL_A "d3dcompiler_43.dll"

typedef struct {
    LPCSTR Name;
    LPCSTR Definition;
} D3D_SHADER_MACRO;

DEFINE_GUID(IID_ID3D10Blob, 0x8ba5fb08, 0x5195, 0x40e2, 0xac, 0x58,
 0xd, 0x98, 0x9c, 0x3a, 0x1, 0x2);

typedef struct ID3D10BlobVtbl {
    BEGIN_INTERFACE

    HRESULT ( STDMETHODCALLTYPE *QueryInterface )
            (ID3D10Blob * This, REFIID riid, void **ppvObject);

    ULONG   ( STDMETHODCALLTYPE *AddRef )(ID3D10Blob * This);
    ULONG   ( STDMETHODCALLTYPE *Release )(ID3D10Blob * This);
    LPVOID  ( STDMETHODCALLTYPE *GetBufferPointer )(ID3D10Blob * This);
    SIZE_T  ( STDMETHODCALLTYPE *GetBufferSize )(ID3D10Blob * This);

    END_INTERFACE
} ID3D10BlobVtbl;

#define ID3D10Blob_QueryInterface(This,riid,ppvObject) \
    ( (This)->lpVtbl -> QueryInterface(This,riid,ppvObject) )

#define ID3D10Blob_AddRef(This) \
    ( (This)->lpVtbl -> AddRef(This) )

#define ID3D10Blob_Release(This) \
    ( (This)->lpVtbl -> Release(This) )

#define ID3D10Blob_GetBufferPointer(This) \
    ( (This)->lpVtbl -> GetBufferPointer(This) )

#define ID3D10Blob_GetBufferSize(This) \
    ( (This)->lpVtbl -> GetBufferSize(This) )

interface ID3D10Blob
{
    CONST_VTBL struct ID3D10BlobVtbl *lpVtbl;
};

typedef ID3D10Blob ID3DBlob;

typedef HRESULT (WINAPI *pD3DCompile)
    (LPCVOID                         pSrcData,
     SIZE_T                          SrcDataSize,
     LPCSTR                          pFileName,
     CONST D3D_SHADER_MACRO*         pDefines,
     void*/*ID3DInclude* */          pInclude,
     LPCSTR                          pEntrypoint,
     LPCSTR                          pTarget,
     UINT                            Flags1,
     UINT                            Flags2,
     ID3DBlob**                      ppCode,
     ID3DBlob**                      ppErrorMsgs);

Now we can load the D3DCompiler DLL, import the function via GetProcAddress and then compile our shader:

    HINSTANCE hD3DCompiler = LoadLibraryA(D3DCOMPILER_DLL_A);
    pD3DCompile D3DCompile = NULL;

    if (hD3DCompiler) {
        D3DCompile = (pD3DCompile) GetProcAddress(hD3DCompiler, "D3DCompile");
    }

    ID3DBlob* shaderBlob = NULL;
    ID3DBlob* errorMsg = NULL;
    D3DCompile(vsSource, strlen(vsSource), NULL, NULL, NULL, "main", "vs_2_0",
               0, 0, &shaderBlob, &errorMsg);
    if (errorMsg) {
        char text[1024];
        sprintf(text, "D3DCompile failed:\n%s",
               (char*) ID3D10Blob_GetBufferPointer(errorMsg));
        MessageBoxA(NULL, text, "Error", MB_OK|MB_ICONERROR|MB_TASKMODAL);
        ID3D10Blob_Release(errorMsg);
        exit(-1);
    }

    IDirect3DVertexShader9* shader = NULL;
    if (shaderBlob) {
        gD3DDevice->CreateVertexShader(
           (DWORD *) ID3D10Blob_GetBufferPointer(shaderBlob),
            &shader
        );
        ID3D10Blob_Release(shaderBlob);
    }