DirectX9 SDK Samples(5) Tutorial 5: Using Texture Maps

Step 1 - Defining a Custom Vertex Format

// A structure for our custom vertex type. Texture coordinates were added.struct CUSTOMVERTEX{    D3DXVECTOR3 position; // The position    D3DCOLOR    color;    // The color#ifndef SHOW_HOW_TO_USE_TCI    FLOAT       tu, tv;   // The texture coordinates#endif};// Custom flexible vertex format (FVF), which describes custom vertex structure#ifdef SHOW_HOW_TO_USE_TCI#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_DIFFUSE)#else#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_DIFFUSE|D3DFVF_TEX1)#endif

设定FVF。

Step 2 - Initializing Screen Geometry

if( FAILED( D3DXCreateTextureFromFile( g_pd3dDevice, "Banana.bmp",&g_pTexture ) ) )return E_FAIL;

首先需要载入纹理。

for( DWORD i=0; i<50; i++ ){    FLOAT theta = (2*D3DX_PI*i)/(50-1);        pVertices[2*i+0].position = D3DXVECTOR3( sinf(theta),-1.0f, cosf(theta) );        pVertices[2*i+0].color    = 0xffffffff;#ifndef SHOW_HOW_TO_USE_TCI        pVertices[2*i+0].tu       = ((FLOAT)i)/(50-1);        pVertices[2*i+0].tv       = 1.0f;#endif        pVertices[2*i+1].position = D3DXVECTOR3( sinf(theta), 1.0f, cosf(theta) );        pVertices[2*i+1].color    = 0xff808080;#ifndef SHOW_HOW_TO_USE_TCI        pVertices[2*i+1].tu       = ((FLOAT)i)/(50-1);        pVertices[2*i+1].tv       = 0.0f;#endif}

然后在创建圆柱的代码中加入纹理坐标。

Step 3 - Rendering the Scene

g_pd3dDevice->SetTexture( 0, g_pTexture );

先设定纹理为第0层，固定管线中最多可以8层，也就是说序号为0到7。

接下来的一大段代码是关于设定纹理和纹理状态。

    // Setup texture. Using textures introduces the texture stage states, which    //   govern how textures get blended together (in the case of multiple    //   textures) and lighting information. In this case, you are modulating    //   (blending) your texture with the diffuse color of the vertices.    g_pd3dDevice->SetTexture( 0, g_pTexture );    g_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLOROP,   D3DTOP_MODULATE );    g_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );    g_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );    g_pd3dDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP,   D3DTOP_DISABLE );#ifdef SHOW_HOW_TO_USE_TCI    // Note: To use Direct3D texture coordinate generation, use the stage state    // D3DTSS_TEXCOORDINDEX, as shown below. In this example, you are using    // the position of the vertex in camera space to generate texture    // coordinates. The tex coord index (TCI) parameters are passed into a    // texture transform, which is a 4x4 matrix that transforms the x,y,z    // TCI coordinates into tu, tv texture coordinates.    // In this example, the texture matrix is set up to     // transform the texture from (-1,+1) position coordinates to (0,1)     // texture coordinate space:    //    tu =  0.5*x + 0.5    //    tv = -0.5*y + 0.5    D3DXMATRIXA16 mat;    mat._11 = 0.25f; mat._12 = 0.00f; mat._13 = 0.00f; mat._14 = 0.00f;    mat._21 = 0.00f; mat._22 =-0.25f; mat._23 = 0.00f; mat._24 = 0.00f;    mat._31 = 0.00f; mat._32 = 0.00f; mat._33 = 1.00f; mat._34 = 0.00f;    mat._41 = 0.50f; mat._42 = 0.50f; mat._43 = 0.00f; mat._44 = 1.00f;    g_pd3dDevice->SetTransform( D3DTS_TEXTURE0, &mat );    g_pd3dDevice->SetTextureStageState( 0, D3DTSS_TEXTURETRANSFORMFLAGS,     D3DTTFF_COUNT2 );    g_pd3dDevice->SetTextureStageState( 0, D3DTSS_TEXCOORDINDEX,     D3DTSS_TCI_CAMERASPACEPOSITION );#endif

老实说，我很奇怪为什么设置这么多参数，因为龙书中很多都用了默认参数。这里居然没有设定MIN、MAX和MIP，这我也感到相当奇怪。
宏定义中的代码是用到了TCI，我觉得平常是用不到了呃。