The A6 engine defaults to A5 mode on slower video cards. This mode displays objects with some of the new material effects and shaders as transparent (Enviroment Reflection or Normal Mapping for example). I believe this is because these shaders are incorporating a .tga with alpha channel, and when the shader doesn't work correctly, the model just picks up the transparency from the alpha.

What's the best way to create a fallback such that the model simply reverts to opaque in A5 mode?