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Brilliant thanks that helps a great deal I have noticed not every RW material is on the list but doesn't matter these will do for what I need anyways . By the way as you can see by my model the logo is on the top part of the hotel, now in real life they are blended into the windows is there a way of doing that? If so how.

Hi everyone I'm trying to add a light effect onto my models and just wanted to know do windows need to be a separate texture file or can I use a new shader by creating a plane polygon for the window texture on a full texture file with the windows already on it?
Anyone who can answer this would be a great help cheers, Ian.

I may not understand the question but at any rate, the texture for additive light (AddTexAlphaDiff) contains the colour of the light that is added on top of the model colour and an alpha channel that defines, where the effect is used.

So you need one image that is the normal texture and another that is just yellow on the parts that are lit and black and/or transparent on the others.

That said, I believe it is ok to stick this second image in an otherwise unused spot on the normal texture.

I just don't know how much you gain doing so.

Hi AndiS thanks for the information I'll give this a try see how I get on. Basically what I am trying to say to say is I have windows on a large texture file with lots of other images like brick wall, rooves and other bits (2048x2048) on the texture file and was wondering if the windows in that image could be lit up or do they need to be a separate texture file itself. Hope this explains my original post cheers, Ian.

You can take the following steps:

1. Make a copy of the normal texture, paint yellow over it where you want the windows to shine. Make the rest transparent. Get that working. It is wasteful, but simple and a good first step.
2. Simply shrink the yellowish texture for the light. You will find that even at 512x512 or 256x256 it will be fine because the shine is just that, you don't want details in it like you want on a brick wall. This requires no changes to the UV map. The coordinates are stored as floats between 0 and 1 internally, so the texture size does not matter at all.
3. If the windows only use a small part of the normal texture, then solution 2 is still wasteful. You ought to read into "second UV map" in this case. In Blender, or whatever you use, you are not restricted to just one UV map per model. But it takes a bit of reading, experimenting, head scratching and I do not have a concise guide to it at hand.