You create a cubic environment map texture by calling the D3DX8.CreateCubeTexture method. Cubic environment map textures must be square, with dimensions that are a power of two.

The following code shows how your Microsoft® Visual Basic® application might create a simple cubic environment map.

'
' For this example, d3dDevice is a valid Direct3DDevice8 
' object and g_D3DX is a valid Direct3DX object.
'
Dim CubeMap As Direct3DCubeTexture8 CubeTexture

Set CubeMap = g_D3DX.CreateCubeTexture( d3dDevice, 256, 1, D3DUSAGE_RENDERTARGET, _
                                        D3DFMT_R8G8B8, D3DPOOL_MANAGED )

You can navigate between faces of a cubic environment map by using the Direct3DCubeTexture8.GetCubeMapSurface method.

The following code example uses GetCubeMapSurface to retrieve the cube-map surface used for the positive-y face (face 2).

'
' For this example, CubeMap is a valid 
' Direct3DCubeTexture8 object.
'
Dim Face2 As Direct3DSurface8

Set Face2 = CubeMap.GetCubeMapSurface( D3DCUBEMAP_FACE_POSITIVE_Y, 0 )

The first parameter that GetAttachedSurface accepts is a CONST_D3DCUBEMAP_FACES enumerated value that describes the attached surface that the method should retrieve. The second parameter tells Microsoft® Direct3D® which level of a mipmapped cube texture to retrieve. Because this cube-map is not mipmapped, 0 is used here.

The following Microsoft® Visual Basic® code example prepares and sets a view matrix according to the face being rendered.

'
' For this example, CubeMap is a valid Direct3DCubeTexture8 object
' and m_D3DDevice is a valid Direct3DDevice8 object.
'
Sub RenderFaces

    ' Save transformation matrices of the device.
    Dim matProjSave As D3DMATRIX, _
        matViewSave As D3DMATRIX
    m_D3DDevice.GetTransform D3DTS_VIEW, matViewSave
    m_D3DDevice.GetTransform D3DTS_PROJECTION, matProjSave

    ' Store the current back buffer and z-buffer.
    Dim BackBuffer As Direct3DSurface8, _
        Zbuffer As Direct3DSurface8
    Set BackBuffer = m_D3DDevice.GetRenderTarget()
    Set Zbuffer = m_D3DDevice.GetDepthStencilSurface()

Remember, each face of a cubic environment map represents a 90-degree field of view. Unless your application requires a different field of view angle—for special effects, for example—take care to set the projection matrix accordingly.

This code example creates and sets a projection matrix for the most common case.

    ' Use 90-degree field of view in the projection.
    Dim matProj As D3DMATRIX
    D3DXMatrixPerspectiveFovLH matProj, g_pi/4, 1, 1/2, 1000
    m_D3DDevice.SetTransform D3DTS_PROJECTION, matProj

    ' Loop through the six faces of the cube map.
    Dim i As Integer
    For i = 0 To 6

        'Standard view that will be overridden below.
        Dim vEnvEyePt As D3DVECTOR, _
            vLookatPt As D3DVECTOR, _
            vUpVec As D3DVECTOR

        Select Case i

            case D3DCUBEMAP_FACE_POSITIVE_X:
                vLookatPt.x = 1#: vUpVec.y = 1#

            case D3DCUBEMAP_FACE_NEGATIVE_X:
                vLookatPt.x = -1#: vUpVec.y = 1#

            case D3DCUBEMAP_FACE_POSITIVE_Y:
                vLookatPt.y = 1#: vUpVec.z = -1#

            case D3DCUBEMAP_FACE_NEGATIVE_Y:
                vLookatPt.y = -1#: vUpVec.z = 1#

            case D3DCUBEMAP_FACE_POSITIVE_Z:
                vLookatPt.z = 1#: vUpVec.y = 1#

            case D3DCUBEMAP_FACE_NEGATIVE_Z:
                vLookatPt.z = -1#: vUpVec.y = 1#

        End Select

        Dim matView As D3DMATRIX
        D3DXMatrixLookAtLH matView, vEnvEyePt, vLookatPt, vUpVec
        m_D3DDevice.SetTransform D3DTS_VIEW, matView

Once the camera is in position and the projection matrix set, you can render the scene. Each object in the scene should be positioned as you would normally position them. The following code example, provided for completeness, outlines this task.

        ' Get cube surface in order to render to it.
        Dim Face As Direct3DSurface8
        Set Face = CubeMap.GetCubeMapSurface i, 0
        m_D3DDevice.SetRenderTarget Face, Zbuffer
        Set Face = Nothing

        m_D3DDevice.BeginScene
        ' Render scene here.
        m_D3DDevice.EndScene

    Next

    ' Change the render target back to the main back buffer.
    m_D3DDevice.SetRenderTarget BackBuffer, pZBuffer
    Set BackBuffer = Nothing
    Set Zbuffer = Nothing

    // Restore the original transformation matrices.
    m_D3DDevice.SetTransform D3DTS_VIEW, matViewSave
    m_D3DDevice.SetTransform D3DTS_PROJECTION, matProjSave

End Sub

Note the call to the Direct3DDevice8.SetRenderTarget method. When rendering to the cube map faces, you must assign the face as the current render-target surface. Applications that use depth buffers can explicitly create a depth-buffer for the render-target, or reassign an existing depth-buffer to the render-target surface. The code sample above uses the latter method.