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。