计算机科学论坛--DXUT源码分析 ---- 类CDXUTMeshFile

类CDXUTMeshFile位于DXUTMesh.h和DXUTMesh.cpp中，继承自类CDXUTMeshFrame，其实类CDXUTMeshFrame本身只完成一些基础操作，不是最终使用的一个类，CDXUTMeshFile在CDXUTMeshFrame的基础上将各种操作进一步封装。

在.x网格模型中使用框架的主要目的是实现模型自身包含的动画，而CDXUTMeshFile和CDXUTMeshFrame虽然考虑了网格模型的层次框架，可是并没有实现对网格模型动画的播放，所以通常不直接使用这两个类，因为对于不包含动画信息的静态网格模型CDXUTMesh类就已经足够了。当然也完全可以像使用CDXUTMesh类一样使用CDXUTMeshFile类来操作不包含动画信息的网格模型。

来看看CDXUTMeshFile的定义：

//-----------------------------------------------------------------------------
// Name: class CDXUTMeshFile
// Desc: Class for loading and rendering file-based meshes
//-----------------------------------------------------------------------------
class CDXUTMeshFile : public CDXUTMeshFrame
{
HRESULT LoadMesh( LPDIRECT3DDEVICE9 pd3dDevice, LPD3DXFILEDATA pFileData, CDXUTMeshFrame* pParentFrame );
HRESULT LoadFrame( LPDIRECT3DDEVICE9 pd3dDevice, LPD3DXFILEDATA pFileData, CDXUTMeshFrame* pParentFrame );

public:
HRESULT Create( LPDIRECT3DDEVICE9 pd3dDevice, LPCWSTR strFilename );
HRESULT CreateFromResource( LPDIRECT3DDEVICE9 pd3dDevice, LPCWSTR strResource, LPCWSTR strType );

    // For pure devices, specify the world transform.
    // If the world transform is not specified on pure devices, this function will fail.
    HRESULT Render( LPDIRECT3DDEVICE9 pd3dDevice, D3DXMATRIX* pmatWorldMatrix = NULL );

CDXUTMeshFile() : CDXUTMeshFrame( L"CDXUTMeshFile_Root" ) {}
};

LoadMesh()负责从ID3DXFileData中加载一个网格，该函数是内部调用的，其实质是调用CDXUTMesh::Create()函数来加载。

HRESULT CDXUTMeshFile::LoadMesh(LPDIRECT3DDEVICE9 pd3dDevice, LPD3DXFILEDATA pFileData, CDXUTMeshFrame* pParentFrame)
{
    // Currently only allowing one mesh per frame
    if( pParentFrame->m_pMesh )
        return E_FAIL;

// Get the mesh name

    CHAR  strAnsiName[512] = {0};
    WCHAR strName[512];
    SIZE_T dwNameLength = 512;
    HRESULT hr;

if( FAILED( hr = pFileData->GetName(strAnsiName, &dwNameLength) ) )
return hr;

MultiByteToWideChar(CP_ACP, 0, strAnsiName, -1, strName, 512);
strName[511] = 0;

// Create the mesh

pParentFrame->m_pMesh = new CDXUTMesh(strName);

if( pParentFrame->m_pMesh == NULL )
return E_OUTOFMEMORY;

pParentFrame->m_pMesh->Create( pd3dDevice, pFileData );

return S_OK;
}

LoadFrame()用于从ID3DXFileData中加载一个框架：

HRESULT CDXUTMeshFile::LoadFrame(LPDIRECT3DDEVICE9 pd3dDevice, LPD3DXFILEDATA pFileData, CDXUTMeshFrame* pParentFrame)
{
    LPD3DXFILEDATA   pChildData = NULL;
    GUID             Guid;
    SIZE_T             cbSize;
    CDXUTMeshFrame*  pCurrentFrame;
    HRESULT             hr;

    // Get the type of the object
    if( FAILED( hr = pFileData->GetType( &Guid ) ) )
        return hr;

    if(Guid == TID_D3DRMMesh)
    {
        hr = LoadMesh(pd3dDevice, pFileData, pParentFrame);

        if( FAILED(hr) )
            return hr;
    }
    if(Guid == TID_D3DRMFrameTransformMatrix)
    {
        D3DXMATRIX* pmatMatrix;
        hr = pFileData->Lock(&cbSize, (LPCVOID*) &pmatMatrix);

if( FAILED(hr) )
return hr;

        // Update the parent's matrix with the new one
        pParentFrame->SetMatrix(pmatMatrix);
    }
    if(Guid == TID_D3DRMFrame)
    {
        // Get the frame name
        CHAR   strAnsiName[512] = "";
        WCHAR  strName[512];
        SIZE_T dwNameLength = 512;
        SIZE_T cChildren;

if( FAILED( hr = pFileData->GetName(strAnsiName, &dwNameLength) ) )
return hr;

MultiByteToWideChar(CP_ACP, 0, strAnsiName, -1, strName, 512);
strName[511] = 0;

        // Create the frame
        pCurrentFrame = new CDXUTMeshFrame(strName);
        if(pCurrentFrame == NULL)
            return E_OUTOFMEMORY;

pCurrentFrame->m_pNext = pParentFrame->m_pChild;
pParentFrame->m_pChild = pCurrentFrame;

// Enumerate child objects

pFileData->GetChildren(&cChildren);

        for (UINT iChild = 0; iChild < cChildren; iChild++)
        {
            // Query the child for its FileData
            hr = pFileData->GetChild(iChild, &pChildData);

            if( SUCCEEDED(hr) )
            {
                hr = LoadFrame(pd3dDevice, pChildData, pCurrentFrame);
                SAFE_RELEASE( pChildData );
            }

            if( FAILED(hr) )
                return hr;
        }
    }

return S_OK;
}
首先，该函数调用GetType()获取对象的GUID：
// Get the type of the object if( FAILED( hr = pFileData->GetType( &Guid ) ) ) return hr;
接下来根据GUID分别进行相应的操作，若是网格则调用LoadMesh()加载网格，若是框架变换矩阵则设置变换矩阵，若是框架，相应的操作有些复杂，首先获取框架的名称并将其转化为widechar类型：

if( FAILED( hr = pFileData->GetName(strAnsiName, &dwNameLength) ) ) return hr;
MultiByteToWideChar(CP_ACP, 0, strAnsiName, -1, strName, 512); strName[511] = 0;
接着新建一个CDXUTMeshFrame对象并将其添加进链表：

// Create the frame pCurrentFrame = new CDXUTMeshFrame(strName); if(pCurrentFrame == NULL) return E_OUTOFMEMORY;
pCurrentFrame->m_pNext = pParentFrame->m_pChild; pParentFrame->m_pChild = pCurrentFrame;
最后遍历子框架并递归调用LoadFrame()加载框架:

        // Enumerate child objects
        pFileData->GetChildren(&cChildren);
        for (UINT iChild = 0; iChild < cChildren; iChild++)        {            // Query the child for its FileData            hr = pFileData->GetChild(iChild, &pChildData);
            if( SUCCEEDED(hr) )            {                hr = LoadFrame(pd3dDevice, pChildData, pCurrentFrame);                SAFE_RELEASE( pChildData );            }
            if( FAILED(hr) )                return hr;        }

第一个Create()函数负责从模型文件加载网格模型：

HRESULT CDXUTMeshFile::Create(LPDIRECT3DDEVICE9 pd3dDevice, LPCWSTR strFilename)
{
    LPD3DXFILE           pDXFile   = NULL;
    LPD3DXFILEENUMOBJECT pEnumObj  = NULL;
    LPD3DXFILEDATA       pFileData = NULL;
    HRESULT hr;
    SIZE_T cChildren;

    // Create a x file object
    if( FAILED( hr = D3DXFileCreate(&pDXFile) ) )
        return E_FAIL;

    // Register templates for d3drm and patch extensions.
    if( FAILED( hr = pDXFile->RegisterTemplates((void*) D3DRM_XTEMPLATES, D3DRM_XTEMPLATE_BYTES) ) )
    {
        SAFE_RELEASE( pDXFile );
        return E_FAIL;
    }

// Find the path to the file, and convert it to ANSI (for the D3DXOF API)

    WCHAR strPath[MAX_PATH];
    CHAR  strPathANSI[MAX_PATH];
    DXUTFindDXSDKMediaFileCch(strPath, sizeof(strPath) / sizeof(WCHAR), strFilename);

    WideCharToMultiByte(CP_ACP, 0, strPath, -1, strPathANSI, MAX_PATH, NULL, NULL);
    strPathANSI[MAX_PATH - 1] = 0;

    // Create enum object
    hr = pDXFile->CreateEnumObject((void*) strPathANSI, D3DXF_FILELOAD_FROMFILE, &pEnumObj);

    if( FAILED(hr) )
    {
        SAFE_RELEASE( pDXFile );
        return hr;
    }

// Enumerate top level objects (which are always frames)
pEnumObj->GetChildren(&cChildren);

    for (UINT iChild = 0; iChild < cChildren; iChild++)
    {
        hr = pEnumObj->GetChild(iChild, &pFileData);
        if (FAILED(hr))
            return hr;

hr = LoadFrame(pd3dDevice, pFileData, this);
SAFE_RELEASE(pFileData);

        if( FAILED(hr) )
        {
            SAFE_RELEASE(pEnumObj);
            SAFE_RELEASE(pDXFile);
            return E_FAIL;
        }
    }

    SAFE_RELEASE(pFileData);
    SAFE_RELEASE(pEnumObj);
    SAFE_RELEASE(pDXFile);

    return S_OK;
}
首先函数创建了一个ID3DXFileData对象并注册了XFILE标准模板：
    // Create a x file object    if( FAILED( hr = D3DXFileCreate(&pDXFile) ) )        return E_FAIL;
    // Register templates for d3drm and patch extensions.    if( FAILED( hr = pDXFile->RegisterTemplates((void*) D3DRM_XTEMPLATES, D3DRM_XTEMPLATE_BYTES) ) )    {        SAFE_RELEASE( pDXFile );        return E_FAIL;    }
接下来查找网格模型文件将路径存储在strPath中，并将该路径转化为ANSI类型存储在strPathANSI中：

    // Find the path to the file, and convert it to ANSI (for the D3DXOF API)
    WCHAR strPath[MAX_PATH];    CHAR  strPathANSI[MAX_PATH];    DXUTFindDXSDKMediaFileCch(strPath, sizeof(strPath) / sizeof(WCHAR), strFilename);
    WideCharToMultiByte(CP_ACP, 0, strPath, -1, strPathANSI, MAX_PATH, NULL, NULL);    strPathANSI[MAX_PATH - 1] = 0;
再接下来创建一个ID3DXFileEnumObject枚举对象负责从.x文件中读取数据：

// Create enum object hr = pDXFile->CreateEnumObject((void*) strPathANSI, D3DXF_FILELOAD_FROMFILE, &pEnumObj);
if( FAILED(hr) ) { SAFE_RELEASE( pDXFile ); return hr; }
函数CreateEnumObject()声明如下：

Creates an enumerator object that will read a .x file.

HRESULT CreateEnumObject( LPCVOID pvSource, D3DXF_FILELOADOPTIONS loadflags, ID3DXFileEnumObject ** ppEnumObj);
Parameters
pvSource
[out] The data source. Either:
A file name
A D3DXF_FILELOADMEMORY structure
A D3DXF_FILELOADRESOURCE structure
Depending on the value of loadflags.
loadflags
[in] Value that specifies the source of the data. This value can be one of the D3DXF_FILELOADOPTIONS flags.
ppEnumObj
[out] Address of a pointer to an ID3DXFileEnumObject interface, representing the created enumerator object.
Return Values
If the method succeeds, the return value is S_OK. If the method fails, the return value can be one of the following: D3DXFERR_BADVALUE, D3DXFERR_PARSEERROR.

Remarks
After using this method, use one of the ID3DXFileEnumObject methods to retrieve a data object.

再接下来通过ID3DXFileEnumObjec枚举对象读取数据并调用LoadFrame()加载框架：

    // Enumerate top level objects (which are always frames)    pEnumObj->GetChildren(&cChildren);
    for (UINT iChild = 0; iChild < cChildren; iChild++)    {        hr = pEnumObj->GetChild(iChild, &pFileData);        if (FAILED(hr))            return hr;
        hr = LoadFrame(pd3dDevice, pFileData, this);        SAFE_RELEASE(pFileData);
        if( FAILED(hr) )        {            SAFE_RELEASE(pEnumObj);            SAFE_RELEASE(pDXFile);            return E_FAIL;        }    }
最后释放不再使用的COM对象：

SAFE_RELEASE(pFileData); SAFE_RELEASE(pEnumObj); SAFE_RELEASE(pDXFile);

第二个Create()函数与第一个非常类似，只是该函数负责从资源加载网格模型：

HRESULT CDXUTMeshFile::CreateFromResource(LPDIRECT3DDEVICE9 pd3dDevice, LPCWSTR strResource, LPCWSTR strType)
{
    LPD3DXFILE           pDXFile   = NULL;
    LPD3DXFILEENUMOBJECT pEnumObj  = NULL;
    LPD3DXFILEDATA       pFileData = NULL;
    HRESULT hr;
    SIZE_T cChildren;

    // Create a x file object
    if( FAILED( hr = D3DXFileCreate(&pDXFile) ) )
        return E_FAIL;

WideCharToMultiByte(CP_ACP, 0, strType, -1, strTypeAnsi, MAX_PATH, NULL, NULL);
strTypeAnsi[MAX_PATH - 1] = 0;

WideCharToMultiByte(CP_ACP, 0, strResource, -1, strResourceAnsi, MAX_PATH, NULL, NULL);
strResourceAnsi[MAX_PATH - 1] = 0;

D3DXF_FILELOADRESOURCE dxlr;

    dxlr.hModule = NULL;
    dxlr.lpName = strResourceAnsi;
    dxlr.lpType = strTypeAnsi;

// Create enum object
hr = pDXFile->CreateEnumObject((void*) &dxlr, D3DXF_FILELOAD_FROMRESOURCE, &pEnumObj);

    if( FAILED(hr) )
    {
        SAFE_RELEASE( pDXFile );
        return hr;
    }

// Enumerate top level objects (which are always frames)

pEnumObj->GetChildren(&cChildren);

    for (UINT iChild = 0; iChild < cChildren; iChild++)
    {
        hr = pEnumObj->GetChild(iChild, &pFileData);
        if (FAILED(hr))
            return hr;

hr = LoadFrame(pd3dDevice, pFileData, this);
SAFE_RELEASE( pFileData );

        if( FAILED(hr) )
        {
            SAFE_RELEASE(pEnumObj);
            SAFE_RELEASE(pDXFile);
            return E_FAIL;
        }
    }

    SAFE_RELEASE(pFileData);
    SAFE_RELEASE(pEnumObj);
    SAFE_RELEASE(pDXFile);

return S_OK;
}

唯一需要解释的代码是：

    D3DXF_FILELOADRESOURCE dxlr;
    dxlr.hModule = NULL;    dxlr.lpName = strResourceAnsi;    dxlr.lpType = strTypeAnsi;
    // Create enum object    hr = pDXFile->CreateEnumObject((void*) &dxlr, D3DXF_FILELOAD_FROMRESOURCE, &pEnumObj);