# XNA HLSL Exclude texture?

I'm going through HLSL tutorials and I have lighting and texturing setup. Right now in my shader I take a texture, but if I leave that variable blank it gives me an error. Half of my models have textures and the other half don't, is there a way to "skip" the texturing part for the models that don't have them and set it for the models that do without having to make a completely seperate shader that only deals with lighting?

Also, whilst I'm asking this, is saturate and normalize the same thing?

Thanks

#if USE_TEXTURES