Step 2: Initializing Screen Geometry

Before rendering, the Texture sample project calls InitGeometry, an application-defined function that creates a texture and initializes the geometry for a cylinder.

Textures are created from file-based images. The following code fragment uses D3DXCreateTextureFromFile to create a texture from Banana.bmp that will be used to cover the surface of the cylinder.

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

The first parameter that D3DXCreateTextureFromFile accepts is a pointer to the Microsoft?Direct3D?device that will be used to render the texture. The second parameter is a pointer to an ANSI string that specifies the filename from which to create the texture. This sample specifies Banana.bmp to load the image from that file. The third parameter is the address of a pointer to a texture object.

When the banana texture is loaded and ready to use, the next step is to create the cylinder. The following code sample fills the vertex buffer with a cylinder. Note that each point has the texture coordinates (tu, tv).

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
}

Each vertex includes position, color, and texture coordinates. The code sample above sets the texture coordinates for each point so that the texture will wrap smoothly around the cylinder.

Now that the texture is loaded and the vertex buffer is ready for rendering, it is time to render the display, as described in Step 3: Rendering the Scene.