函数CreateMaterials()用于创建网格模型中所需的材质和纹理，我们来看看CreateMaterials()的实现：

 

函数首先根据材质数来创建相应的材质缓存、纹理缓存、纹理文件名缓存：

    m_dwNumMaterials = dwNumMaterials;

    if( d3dxMtrls && m_dwNumMaterials > 0 )
    {
        // Allocate memory for the materials and textures

        m_pMaterials = new D3DMATERIAL9[m_dwNumMaterials];
        if( m_pMaterials == NULL )
            return E_OUTOFMEMORY;

        m_pTextures = new LPDIRECT3DBASETEXTURE9[m_dwNumMaterials];
        if( m_pTextures == NULL )
            return E_OUTOFMEMORY;

        m_strMaterials = new CHAR[m_dwNumMaterials][MAX_PATH];
        if( m_strMaterials == NULL )
            return E_OUTOFMEMORY;

接下来复制材质数据：

        // Copy each material and create its texture
        for( DWORD i=0; i<m_dwNumMaterials; i++ )
        {
            // Copy the material
            m_pMaterials[i]         = d3dxMtrls[i].MatD3D;
           m_pMaterials[i].Ambient = m_pMaterials[i].Diffuse;	// add by me

            m_pTextures[i]          = NULL;

如果模型中指定纹理文件名则创建纹理缓存，首先将pTextureFilename复制到m_strMaterials中，接着根据strPath和strTextureTemp生成纹理图的完整路径（可能是绝对路径也可能是相对路径）：

            // Create a texture
            if( d3dxMtrls[i].pTextureFilename )
            {
                StringCchCopyA( m_strMaterials[i], MAX_PATH, d3dxMtrls[i].pTextureFilename );

                WCHAR strTexture[MAX_PATH];
                WCHAR strTextureTemp[MAX_PATH];
                D3DXIMAGE_INFO ImgInfo;

                // First attempt to look for texture in the same folder as the input folder.

                MultiByteToWideChar( CP_ACP, 0, d3dxMtrls[i].pTextureFilename, -1, strTextureTemp, MAX_PATH );
                strTextureTemp[MAX_PATH-1] = 0;

                StringCchCopy( strTexture, MAX_PATH, strPath );
                StringCchCat( strTexture, MAX_PATH, strTextureTemp );

StringCchCat()的声明如下：

 

接下来调用D3DXGetImageInfoFromFile()从文件中获取图像数据，如果获取失败，则在搜索路径中增加一层目录media来搜索：

                // Inspect the texture file to determine the texture type.
                if( FAILED( D3DXGetImageInfoFromFile( strTexture, &ImgInfo ) ) )
                {
                    // Search the media folder
                    if( FAILED( DXUTFindDXSDKMediaFileCch( strTexture, MAX_PATH, strTextureTemp ) ) )
                        continue;  // Can't find. Skip.

                    D3DXGetImageInfoFromFile( strTexture, &ImgInfo );
                }

D3DXGetImageInfoFromFile()的声明如下：

Retrieves information about a given image file.

HRESULT D3DXGetImageInfoFromFile(
  LPCSTR pSrcFile,
  D3DXIMAGE_INFO * pSrcInfo
);

Parameters

pSrcFile

[in] File name of image to retrieve information about. If UNICODE or _UNICODE are defined, this parameter type is LPCWSTR, otherwise, the type is LPCSTR.

pSrcInfo

[in] Pointer to a D3DXIMAGE_INFO structure to be filled with the description of the data in the source file.

Return Values

If the function succeeds, the return value is D3D_OK. If the function fails, the return value can be the following: D3DERR_INVALIDCALL

Remarks

This function supports both Unicode and ANSI strings.

D3DXIMAGE_INFO

Returns a description of the original contents of an image file.

typedef struct D3DXIMAGE_INFO {
    UINT Width;
    UINT Height;
    UINT Depth;
    UINT MipLevels;
    D3DFORMAT Format;
    D3DRESOURCETYPE ResourceType;
    D3DXIMAGE_FILEFORMAT ImageFileFormat;
} D3DXIMAGE_INFO, *LPD3DXIMAGE_INFO;

Members

Width

Width of original image in pixels.

Height

Height of original image in pixels.

Depth

Depth of original image in pixels.

MipLevels

Number of mip levels in original image.

Format

A value from the D3DFORMAT enumerated type that most closely describes the data in the original image.

ResourceType

Represents the type of the texture stored in the file. It is either D3DRTYPE_TEXTURE, D3DRTYPE_VOLUMETEXTURE, or D3DRTYPE_CubeTexture.

ImageFileFormat

Represents the format of the image file.

D3DXIMAGE_FILEFORMAT

Describes the supported image file formats. See Remarks for descriptions of these formats.

typedef enum D3DXIMAGE_FILEFORMAT
{
    D3DXIFF_BMP = 0,
    D3DXIFF_JPG = 1,
    D3DXIFF_TGA = 2,
    D3DXIFF_PNG = 3,
    D3DXIFF_DDS = 4,
    D3DXIFF_PPM = 5,
    D3DXIFF_DIB = 6,
    D3DXIFF_HDR = 7,
    D3DXIFF_PFM = 8,
    D3DXIFF_FORCE_DWORD = 0x7fffffff,
} D3DXIMAGE_FILEFORMAT, *LPD3DXIMAGE_FILEFORMAT;

Constants

D3DXIFF_BMP

Windows bitmap (BMP) file format.

D3DXIFF_JPG

Joint Photographics Experts Group (JPEG) compressed file format.

D3DXIFF_TGA

Truevision (Targa, or TGA) image file format.

D3DXIFF_PNG

Portable Network Graphics (PNG) file format.

D3DXIFF_DDS

DirectDraw surface (DDS) file format.

D3DXIFF_PPM

Portable pixmap (PPM) file format.

D3DXIFF_DIB

Windows device-independent bitmap (DIB) file format.

D3DXIFF_HDR

High dynamic range (HDR) file format.

D3DXIFF_PFM

Portable float map file format.

D3DXIFF_FORCE_DWORD

Forces this enumeration to compile to 32 bits in size. Without this value, some compilers would allow this enumeration to compile to a size other than 32 bits. This value is not used.

Remarks

Functions that begin with D3DXLoadxxx support all of the formats listed. Functions that begin with D3DXSavexxx support all but the Truevision (.tga) and portable pixmap (.ppm) formats.

The following table lists the available input and output formats.

File Extension	Description
.bmp	Windows bitmap format. Contains a header that describes the resolution of the device on which the rectangle of pixels was created, the dimensions of the rectangle, the size of the array of bits, a logical palette, and an array of bits that defines the relationship between pixels in the bitmapped image and entries in the logical palette.
.dds	DirectDraw Surface file format. Stores textures, volume textures, and cubic environment maps, with or without mipmap levels, and with or without pixel compression. See DDS File Reference.
.dib	Windows DIB. Contains an array of bits combined with structures that specify width and height of the bitmapped image, color format of the device where the image was created, and resolution of the device used to create that image.
.hdr	HDR format. Encodes each pixel as an RGBE 32-bit color, with 8 bits of mantissa for red, green, and blue, and a shared 8-bit exponent. Each channel is separately compressed with run-length encoding (RLE).
.jpg	JPEG standard. Specifies variable compression of 24-bit RGB color and 8-bit gray-scale Tagged Image File Format (TIFF) image document files.
.pfm	Portable float map format. A raw floating point image format, without any compression. The file header specifies image width, height, monochrome or color, and machine word order. Pixel data is stored as 32-bit floating point values, with 3 values per pixel for color, and one value per pixel for monochrome.
.png	PNG format. A non-proprietary bitmap format using lossless compression.
.ppm	Portable Pixmap format. A binary or ASCII file format for color images that includes image height and width and the maximum color component value.
.tga	Targa or Truevision Graphics Adapter format. Supports depths of 8, 15, 16, 24, and 32 bits, including 8-bit gray scale, and contains optional color palette data, image (x, y) origin and size data, and pixel data.

See Types of Bitmaps (GDI+) for more information on some of these formats.

接下来根据图像的资源类型来创建纹理，如果是纹理资源，则调用D3DXCreateTextureFromFile()来创建纹理，并调用QueryInterface()来请求该类型的接口：

                // Call the appropriate loader according to the texture type.
                switch( ImgInfo.ResourceType )
                {
                    case D3DRTYPE_TEXTURE:
                    {
                        IDirect3DTexture9 *pTex;

                        if( SUCCEEDED( D3DXCreateTextureFromFileW( pd3dDevice, strTexture, &pTex ) ) )
                        {
                            // Obtain the base texture interface
                            pTex->QueryInterface( IID_IDirect3DBaseTexture9, (LPVOID*)&m_pTextures[i] );

                            // Release the specialized instance
                            pTex->Release();
                        }

                        break;
                    }

QueryInterface()的声明如下:

Determines whether the object supports a particular COM interface. If it does, the system increases the object's reference count, and the application can use that interface immediately.

HRESULT QueryInterface(
  REFIID riid,
  LPVOID * ppvObj
);

Parameters

riid

Reference identifier of the interface being requested.

ppvObj

Address of a pointer to fill with the interface pointer if the query succeeds.

Return Values

If the method succeeds, the return value is S_OK.

If the method fails, the return value may be E_NOINTERFACE. Some components also have their own definitions of these error values in their header files.

Remarks

If the application does not need to use the interface retrieved by a call to this method, it must call the IUnknown::Release method for that interface to free it. The IUnknown::QueryInterface method makes it possible to extend objects without interfering with functionality.

如果立方体纹理资源则调用D3DXCreateCubeTextureFromFile()来创建立方体纹理缓存，如果是D3DRTYPE_VOLUMETEXTURE类型的资源，则调用D3DXCreateVolumeTextureFromFile()来创建该类型的纹理资源：

                    case D3DRTYPE_CUBETEXTURE:
                    {
                        IDirect3DCubeTexture9 *pTex;

                        if( SUCCEEDED( D3DXCreateCubeTextureFromFile( pd3dDevice, strTexture, &pTex ) ) )
                        {
                            // Obtain the base texture interface
                            pTex->QueryInterface( IID_IDirect3DBaseTexture9, (LPVOID*)&m_pTextures[i] );

                            // Release the specialized instance
                            pTex->Release();
                        }

                        break;
                    }

                    case D3DRTYPE_VOLUMETEXTURE:
                    {
                        IDirect3DVolumeTexture9 *pTex;

                        if( SUCCEEDED( D3DXCreateVolumeTextureFromFile( pd3dDevice, strTexture, &pTex ) ) )
                        {
                            // Obtain the base texture interface
                            pTex->QueryInterface( IID_IDirect3DBaseTexture9, (LPVOID*)&m_pTextures[i] );

                            // Release the specialized instance
                            pTex->Release();
                        }

                        break;
                    }

D3DXCreateCubeTextureFromFile()的声明如下：

Creates a cube texture from a file.

HRESULT D3DXCreateCubeTextureFromFile(
  LPDIRECT3DDEVICE9 pDevice,
  LPCTSTR pSrcFile,
  LPDIRECT3DCUBETEXTURE9 * ppCubeTexture
);

Parameters

pDevice

[in] Pointer to an IDirect3DDevice9 interface, representing the device to be associated with the cube texture.

pSrcFile

[in] Pointer to a string that specifies the filename. If the compiler settings require Unicode, the data type LPCTSTR resolves to LPCWSTR. Otherwise, the string data type resolves to LPCSTR. See Remarks.

ppCubeTexture

[out] Address of a pointer to an IDirect3DCubeTexture9 interface, representing the created cube texture object.

Return Values

If the function succeeds, the return value is D3D_OK. If the function fails, the return value can be one of the following values: D3DERR_INVALIDCALL.

D3DERR_NOTAVAILABLED3DERR_OUTOFVIDEOMEMORYD3DXERR_INVALIDDATAE_OUTOFMEMORY

Remarks

The compiler setting also determines the function version. If Unicode is defined, the function call resolves to D3DXCreateCubeTextureFromFileW. Otherwise, the function call resolves to D3DXCreateCubeTextureFromFileA because ANSI strings are being used.

The function is equivalent to D3DXCreateCubeTextureFromFileEx(pDevice, pSrcFile, D3DX_DEFAULT, D3DX_DEFAULT, 0, D3DFMT_UNKNOWN, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, 0, NULL, NULL, ppCubeTexture).

This function supports the following file formats: .bmp, .dds, .dib, .hdr, .jpg, .pfm, .png, .ppm, and .tga. See D3DXIMAGE_FILEFORMAT.

Note that a resource created with this function will be placed in the memory class denoted by D3DPOOL_MANAGED.

Filtering is automatically applied to a texture created using this method. The filtering is equivalent to D3DX_FILTER_TRIANGLE | D3DX_FILTER_DITHER in D3DX_FILTER.

D3DXCreateCubeTextureFromFile uses the DirectDraw surface (DDS) file format. The DirectX Texture Editor (dxtex.exe) enables you to generate a cube map from other file formats and save it in the DDS file format.

D3DXCreateVolumeTextureFromFile()的声明如下：

Creates a volume texture from a file.

HRESULT D3DXCreateVolumeTextureFromFile(
  LPDIRECT3DDEVICE9 pDevice,
  LPCTSTR pSrcFile,
  LPDIRECT3DVOLUMETEXTURE9 * ppVolumeTexture
);

Parameters

pDevice

[in] Pointer to an IDirect3DDevice9 interface, representing the device to be associated with the volume texture.

pSrcFile

[in] Pointer to a string that specifies the file name. If the compiler settings require Unicode, the data type LPCTSTR resolves to LPCWSTR. Otherwise, the string data type resolves to LPCSTR. See Remarks.

ppVolumeTexture

[out] Address of a pointer to an IDirect3DVolumeTexture9 interface representing the created texture object.

Return Values

If the function succeeds, the return value is D3D_OK. If the function fails, the return value can be one of the following:

D3DERR_NOTAVAILABLED3DERR_OUTOFVIDEOMEMORYD3DERR_INVALIDCALLD3DXERR_INVALIDDATAE_OUTOFMEMORY

Remarks

The compiler setting also determines the function version. If Unicode is defined, the function call resolves to D3DXCreateVolumeTextureFromFileW. Otherwise, the function call resolves to D3DXCreateVolumeTextureFromFileA because ANSI strings are being used.

The function is equivalent to D3DXCreateVolumeTextureFromFileEx(pDevice, pSrcFile, D3DX_DEFAULT, D3DX_DEFAULT, D3DX_DEFAULT, D3DX_DEFAULT, 0, D3DFMT_UNKNOWN, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, 0, NULL, NULL, ppVolumeTexture).

This function supports the following file formats: .bmp, .dds, .dib, .hdr, .jpg, .pfm, .png, .ppm, and .tga. See D3DXIMAGE_FILEFORMAT.

Mipmapped textures automatically have each level filled with the loaded texture.

When loading images into mipmapped textures, some devices are unable to go to a 1x1 image and this function will fail. If this happens, then the images need to be loaded manually.

Note that a resource created with this function will be placed in the memory class denoted by D3DPOOL_MANAGED.

Filtering is automatically applied to a texture created using this method. The filtering is equivalent to D3DX_FILTER_TRIANGLE | D3DX_FILTER_DITHER in D3DX_FILTER.