Using Texture Coordinate Processing

[C++]

The following are some ways you might use texture coordinate processing to achieve special texturing effects, expressed with psuedo-code.

Animating textures (by translation or rotation) on a model:

Define 2-D texture coordinates in your vertex format:

// Use a single texture, with 2-D texture coordinates. This
// bit-pattern should be expanded to include position, normal, 
// and color information as needed.
DWORD dwFVFTex = D3FVF_TEX1 | D3DFVF_TEXCOORDSIZE2(0);

Configure the rasterizer to use 2-D texture coordinates:

SetTextureStageState(0, D3DTSS_TEXTURETRANSFORMFLAGS, D3DTTFF_COUNT2)

Define and set an appropriate texture coordinate transformation matrix:

// M is a D3DMATRIX being set to translate texture
// coordinates in the U and V directions.
//      1   0  0  0
//      0   1  0  0
//      du dv  1  0 (du and dv change each frame)
//      0   0  0  1

D3DMATRIX M = D3DUtil_SetIdentityMatrix(); // declared in d3dutil.h
M._31 = du; 
M._32 = dv;

Creating texture coordinates as a linear function of a model's camera-space position:

Use the D3DTSS_TCI_CAMERASPACEPOSITION flag to instruct the system to pass the vertex position, in camera space, as input to a texture transformation:

// The input vertices have NO texture coordinates (saving bandwidth!!!)
// 3 texture coordinates are generated by using vertex position in 
// camera space (x, y, z)
SetTextureStageState(0, D3DTSS_TEXCOORDINDEX, D3DTSS_TCI_CAMERASPACEPOSITION)

Instruct the rasterizer to expect 2-D texture coordinates:

// Two output coordinates will be used.
SetTextureStageState(0, D3DTSS_TEXTURETRANSFORMFLAGS, D3DTTFF_COUNT2)

Define and set a matrix that applies a linear function:

// Generate texture coordinates as linear functions 
// such that:
//      u = Ux*x + Uy*x + Uz*x + Uw 
//      v = Vx*x + Vy*x + Vz*x + Vw
// The matrix M for this case is:
//      Ux  Vx  0  0 
//      Uy  Vy  0  0 
//      Uz  Vz  0  0 
//      Uw  Vw  0  0 

SetTransform(D3DTRANSFORMSTATE_TEXTURE0, &M)

Performing environment mapping with a cubic environment map:

Use the D3DTSS_TCI_CAMERASPACEREFLECTIONVECTOR flag to instruct the system to automatically generate texture coordinates (as reflection vectors) for cubic mapping.
```
SetTextureStageState(0, D3DTSS_TEXCOORDINDEX, D3DTSS_TCI_CAMERASPACEREFLECTIONVECTOR)
```
Instruct the rasterizer to expect texture coordinates with 3 elements:
```
SetTextureStageState(0, D3DTSS_TEXTURETRANSFORMFLAGS, D3DTTFF_COUNT3)
```

Performing projective texturing:

Use the D3DTSS_TCI_CAMERASPACEPOSITION flag to instruct the system to pass the vertex position as input to a texture transformation matrix:
```
SetTextureStageState(0, D3DTSS_TEXCOORDINDEX, D3DTSS_TCI_CAMERASPACEPOSITION)
```
Create and apply the texture projection matrix. (This is beyond the scope of this documentation, and is the topic of several industry articles).

Instruct the rasterizer to expect 3-element projected texture coordinates.

// Two output coordinates will be used.
SetTextureStageState(0, D3DTSS_TEXTURETRANSFORMFLAGS, D3DTTF_PROJECTED | D3DTTFF_COUNT3)

[Visual Basic]