[DX9] Turning on/off vertex information

If you want to change the behavior of your shader, then you should change your shader. Your vertex declaration should always accurately reflect the contents of your vertex buffer...using an inaccurate declaration is not a reliable way to control the behavior of your shaders.

Quote:

to show the material of the object instead of its texture

In that particular case, set the texture to white or neutral gray instead of the normal texture.

You can safely ignore a input semantic ("vertex information") in your shaders. So switching to another shader could be considered "disabling a semantic".

If you are concerned about "I don't want to send more to the GPU than I need to", DX 9 provides the concept of streams. Basically you split (de-interleave) your vertices by semantics and provide separate vertex buffers. Note: Using streams does not necessarily improve performance, if that's what you are looking for. But they could provide a flexibility you are currently missing: You can disable a semantic by disabling a stream, if the stream/vertex buffer covers that specific semantic only. Just keep in mind that not sending a semantic that a shader expects will fail. So you will have to switch shaders anyway.

This flexibility comes with the price of considerable greater complexity on the administration/setup side, so if you want to keep your life simple, just switch shaders or use dummy textures, as suggested.

Thanks for your valuable suggestions!

For now I've used the "dummy texture" method. It's working fine.

If I understand it correctly an alternative would be to create two techniques with different pixel shaders: one employing textures and another one that ignores texture data. This way I could switch from one technique to another in my code hence enabling and disabling textures.

Using multiple streams is the most efficient method as it would allow me to send texture data only when it is needed. As this technique seems to be quite complicated I'll try it later.