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Enabling Texture Coordinate Transformations

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The D3DTSS_TEXTURETRANSFORMFLAGS texture stage state controls the application of texture coordinate transformations. Values for this texture stage state are defined by the D3DTEXTURETRANSFORMFLAGS enumerated type.

Texture coordinate transformations are disabled when D3DTSS_TEXTURETRANSFORMFLAGS is set to D3DTTFF_DISABLE (the default value). Assuming that texture coordinate transformations were enabled for stage 0, the following code example disables them.

// For this example, the d3dDevice variable contains a 
// valid pointer to an IDirect3DDevice8 interface.

D3dDevice->SetTextureStageState( 0, D3DTSS_TEXTURETRANSFORMFLAGS,
D3DTTFF_DISABLE );

The other values defined in D3DTEXTURETRANSFORMFLAGS are used to enable texture coordinate transformations, and to control how many resulting texture coordinate elements are passed to the rasterizer. For example, take the following code.

// For this example, the d3dDevice variable contains a 
// valid pointer to an IDirect3DDevice8 interface.

D3dDevice->SetTextureStageState( 0, D3DTSS_TEXTURETRANSFORMFLAGS,
D3DTTFF_COUNT2 );

The D3DTTFF_COUNT2 value instructs the system to apply the transformation matrix set for texture stage 0, and then pass the first two elements of the modified texture coordinates to the rasterizer.

The D3DTTFF_PROJECTED texture transformation flag indicates coordinates for a projected texture. When this flag is specified, the rasterizer divides the elements passed-in by the last element. Take the following code, for example.

// For this example, the d3dDevice variable contains a 
// valid pointer to an IDirect3DDevice8 interface.

d3dDevice->SetTextureStageState( 0, D3DTSS_TEXTURETRANSFORMFLAGS, 
                                   D3DTTFF_COUNT3 | D3DTTFF_PROJECTED );

This example informs the system to pass three texture coordinate elements to the rasterizer. The rasterizer divides the first two elements by the third, producing the 2-D texture coordinates needed to address the texture.

See Also

Texture Coordinate Transformations

 Last updated on Thursday, April 08, 2004

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