Dirt Maps

[Dylan]

I was just searching around for a few new textures and came across some dirt maps.
Now I gather theses are used on a normal texture to roughen it up and make it look dirty. Is this correct?

Can they be used in TR?
If so where do you add them. Do they replace a bump?

One last question.
What is a normal? I see they are a purple looking image of the texture. What is it's purpose?

[Pixero]

A normal map is a image that sets the normal direction of the face. (The direction pointing out from the face.) Its kind of like a bump map. This is good for adding detail without modelling it and is used frequently in games where you need to have rather light models geometry wise.
The different colors r, g, b are for the different directions x, y, z. So for example more red in the image will simulate that that part of the face is pointing more towards the x direction.
Bluish normal maps are in "object space" and green/yellowish are in "world space".

[Ecuadorian]

Hi, Dylan. If I understand correctly, Dirt Maps are masks for multi-layered materials. The concept is similar to using layer masks in Photoshop/GIMP. When I used them in other programs years ago they were a real headache and I wished I could simply add some imperfections that I could see directly in the viewport without having to render to see the result. And in SketchUp you can do this the easy way: Just "Make unique texture" from each wall you want do dirty up and edit it in Photoshop/GIMP.

Or if you want a more interactive way to add imperfections/grafitti/mold to your walls, just load them as transparent PNGs glued to your flat surfaces. For this, all you have to do is load it as image, not as texture, and Twilight will respect the soft transparency. Please note that this adds considerably to render time, however. (And yes, I used a mouse to create this grafitti, I don't use a tablet)

[Gaieus]

Cool Effects, Miguel, thanks. I've been wondering for a while why images (imported as such) do not cause Z-fighting with the texture on the face they are attached on but hey, who cares if this can be turned into a cool trick like this.

[Chris]

We take special care to try to prevent z-fighting of images with geometry. However, it is possible to have z-fighting between images if they overlap.