DirectX9 SDK Samples(14) EffectParam Sample(1)_effectparam示例解释-优快云博客

这个例子是关于着色器参数的，涉及两方面。首先是ParameterBlock，通过参数块将几个参数绑定在一起，用一个句柄设定一组参数，简化参数设定。第二个是ParameterSharing，在创建效果框架时传递EffectPool参数，拥有同一个Pool的效果框架会共享Pool的参数，同时会同步进行更新。具体可以参考SDK Documentation。

下面开始阅读代码。

1全局变量和定义数据

struct MESHLISTDATA
{
    WCHAR   wszName[MAX_PATH];
    WCHAR   wszFile[MAX_PATH];
    DWORD dwNumMat;  // Number of materials.  To be filled in when loading this mesh.
} g_MeshListData[] =
{
    { L"Car", L"car2.x", 0 },
    { L"Banded Earth", L"sphereband.x", 0 },
    { L"Dwarf", L"dwarf\\DwarfWithEffectInstance.x", 0 },
    { L"Virus", L"cytovirus.x", 0 },
    { L"Car", L"car2.x", 0 },
    { L"Banded Earth", L"sphereband.x", 0 },
    { L"Dwarf", L"dwarf\\DwarfWithEffectInstance.x", 0 },
};

首先看到的是一个将要载入的网格的列表，第三个参数载入时设定。

//--------------------------------------------------------------------------------------
struct CMeshMaterial
{
    ID3DXEffect* m_pEffect;
    D3DXHANDLE m_hParam;
    IDirect3DTexture9* m_pTexture;

public:
//省略部分代码
};

接下来是一个材质类，便于管理材质。

//--------------------------------------------------------------------------------------
class CEffectMesh
{
    WCHAR   m_wszMeshFile[MAX_PATH];
    ID3DXMesh* m_pMesh;
    CMeshMaterial* m_pMaterials;
    DWORD m_dwNumMaterials;

public:
//省略部分代码
    void    Render( IDirect3DDevice9* pd3dDevice )
    {
        HRESULT hr;

        for( UINT i = 0; i < m_dwNumMaterials; ++i )
        {
            CMeshMaterial* pMat = &m_pMaterials[i];
            V( pMat->m_pEffect->ApplyParameterBlock( pMat->m_hParam ) );

            UINT cPasses;
            V( pMat->m_pEffect->Begin( &cPasses, 0 ) );
            for( UINT p = 0; p < cPasses; ++p )
            {
                V( pMat->m_pEffect->BeginPass( p ) );
                V( m_pMesh->DrawSubset( i ) );
                V( pMat->m_pEffect->EndPass() );
            }
            V( pMat->m_pEffect->End() );
        }
    }
};

接下来是一个网格类，可以看到该类带有一个材质数组，渲染函数中依次调用材质效果框架渲染材质，当然，用到了ParameterBlock。

ID3DXEffectPool*                g_pEffectPool = NULL;   // Effect pool for sharing parameters
CGrowableArray <CEffectMesh>    g_Meshes;           // List of meshes being rendered
CGrowableArray <D3DXMATRIXA16>  g_amWorld;        // World transform for the meshes

这是三个值得注意的全局变量，一个是效果框架池，另外两个用来渲染网格。

HRESULT CEffectMesh::Create( LPCWSTR wszFileName, IDirect3DDevice9* pd3dDevice )
{
    HRESULT hr;

    WCHAR str[MAX_PATH];
    WCHAR wszMeshPath[MAX_PATH];
    ID3DXBuffer* pAdjacency;
    ID3DXBuffer* pMaterials;
    ID3DXBuffer* pEffectInstance;
    DWORD dwNumMaterials;

    // Save the mesh filename
    wcscpy_s( m_wszMeshFile, MAX_PATH, wszFileName );
//省略，载入网格
    bool bHasNormals = ( m_pMesh->GetFVF() & D3DFVF_NORMAL ) != 0;
    ID3DXMesh* pCloneMesh;
    V_RETURN( m_pMesh->CloneMesh( m_pMesh->GetOptions(), MESHVERTEX::Decl, pd3dDevice, &pCloneMesh ) );
    m_pMesh->Release();
    m_pMesh = pCloneMesh;//这里将载入的网格顶点格式改为需要的格式

//省略

    // Ensure the mesh has correct normals.
    if( !bHasNormals )
        D3DXComputeNormals( m_pMesh, ( DWORD* )pAdjacency->GetBufferPointer() );

    // Allocate material array
    m_pMaterials = new CMeshMaterial[dwNumMaterials];
    if( !m_pMaterials )
        return E_OUTOFMEMORY;

    D3DXMATERIAL* pXMats = ( D3DXMATERIAL* )pMaterials->GetBufferPointer();
    D3DXEFFECTINSTANCE* pEI = ( D3DXEFFECTINSTANCE* )pEffectInstance->GetBufferPointer();
    for( UINT i = 0; i < dwNumMaterials; ++i )
    {
        // Obtain the effect

        hr = S_OK;
        // Try the mesh's directory
        wcscpy_s( str, MAX_PATH, wszMeshPath );
        MultiByteToWideChar( CP_ACP, 0, pEI[i].pEffectFilename, -1, str + lstrlenW( str ), MAX_PATH );

        if( pEI[i].pEffectFilename == NULL )
            hr = E_FAIL;

        WCHAR wszFxName[MAX_PATH];
        MultiByteToWideChar( CP_ACP, 0, pEI[i].pEffectFilename, -1, wszFxName, MAX_PATH );

        if( SUCCEEDED( hr ) )
        {
            WCHAR szTmp[MAX_PATH];
            wcscpy_s( szTmp, MAX_PATH, L"SharedFx\\" );
            wcscat_s( szTmp, MAX_PATH, wszFxName );
            hr = DXUTFindDXSDKMediaFileCch( str, MAX_PATH, szTmp );
            if( FAILED( hr ) )
            {
                // Search the SDK paths
                hr = DXUTFindDXSDKMediaFileCch( str, MAX_PATH, wszFxName );
            }
        }

        if( SUCCEEDED( hr ) )
            DXUTGetGlobalResourceCache().CreateEffectFromFile( pd3dDevice, str, NULL, NULL, g_dwShaderFlags,
                                                               g_pEffectPool,
                                                               &m_pMaterials[i].m_pEffect, NULL );
        if( !m_pMaterials[i].m_pEffect )
        {
            // No valid effect for this material.  Use the default.
            m_pMaterials[i].m_pEffect = g_pEffect;
            m_pMaterials[i].m_pEffect->AddRef();
        }

        // Set the technique this material should use
        D3DXHANDLE hTech;
        m_pMaterials[i].m_pEffect->FindNextValidTechnique( NULL, &hTech );
        m_pMaterials[i].m_pEffect->SetTechnique( hTech );

        // Create a parameter block to include all parameters for the effect.
        m_pMaterials[i].m_pEffect->BeginParameterBlock();
        for( UINT param = 0; param < pEI[i].NumDefaults; ++param )
        {
            D3DXHANDLE hHandle = m_pMaterials[i].m_pEffect->GetParameterByName( NULL,
                                                                                pEI[i].pDefaults[param].pParamName );
            D3DXPARAMETER_DESC desc;
            if( hHandle != NULL )
            {
                m_pMaterials[i].m_pEffect->GetParameterDesc( hHandle, &desc );
                if( desc.Type == D3DXPT_BOOL ||
                    desc.Type == D3DXPT_INT ||
                    desc.Type == D3DXPT_FLOAT ||
                    desc.Type == D3DXPT_STRING )
                {
                    m_pMaterials[i].m_pEffect->SetValue( pEI[i].pDefaults[param].pParamName,
                                                         pEI[i].pDefaults[param].pValue,
                                                         pEI[i].pDefaults[param].NumBytes );
                }
            }
        }

        // Obtain the texture
        hr = S_OK;

        if( pXMats[i].pTextureFilename )
        {
            // Try the mesh's directory first.
            wcscpy_s( str, MAX_PATH, wszMeshPath );
            MultiByteToWideChar( CP_ACP, 0, pXMats[i].pTextureFilename, -1, str + lstrlenW( str ), MAX_PATH );
            // If the texture file is not in the same directory as the mesh, search the SDK paths.
            if( INVALID_FILE_ATTRIBUTES == ::GetFileAttributesW( str ) )
            {
                WCHAR wszTexName[MAX_PATH];
                // Search the SDK paths
                MultiByteToWideChar( CP_ACP, 0, pXMats[i].pTextureFilename, -1, wszTexName, MAX_PATH );
                hr = DXUTFindDXSDKMediaFileCch( str, MAX_PATH, wszTexName );
            }

            if( SUCCEEDED( hr ) )
                DXUTGetGlobalResourceCache().CreateTextureFromFile( pd3dDevice, str, &m_pMaterials[i].m_pTexture );
        }

        if( !m_pMaterials[i].m_pTexture )
        {
            // No texture or texture fails to load. Use the default texture.
            m_pMaterials[i].m_pTexture = g_pDefaultTex;
            m_pMaterials[i].m_pTexture->AddRef();
        }

        // Include the texture in the parameter block if the effect requires one.
        D3DXHANDLE hTexture = m_pMaterials[i].m_pEffect->GetParameterByName( NULL, "g_txScene" );
        if( hTexture )
            m_pMaterials[i].m_pEffect->SetTexture( hTexture, m_pMaterials[i].m_pTexture );

        // Include the environment map texture in the parameter block if the effect requires one.
        hTexture = m_pMaterials[i].m_pEffect->GetParameterByName( NULL, "g_txEnvMap" );
        if( hTexture )
            m_pMaterials[i].m_pEffect->SetTexture( hTexture, g_pEnvMapTex );

        // Save the parameter block
        m_pMaterials[i].m_hParam = m_pMaterials[i].m_pEffect->EndParameterBlock();
    }

    SAFE_RELEASE( pAdjacency );
    SAFE_RELEASE( pMaterials );
    SAFE_RELEASE( pEffectInstance );
    m_dwNumMaterials = dwNumMaterials;
    return S_OK;
}

最后看看CEffectMesh的Create函数。可以看到在载入纹理时同时创建ParameterBlock。下一节将阅读剩下的代码。