Terrain

#21 Just another thought about normal maps: Maybe it would serve as a way to help automatically generate that mask. And then comparing the normals per pixel, you could choose which material makes it into the pixel.

I'm probably not saying anything new, but artists would still have control over it, and the ever problematic alpha channel editing could be kept out of the loop.

(I'm thinking about the way diffuse textures have specular maps in the alpha channel for tgea - but not many people used it, simply because most better known tools don't have direct control over editing the alpha channel)

#22 Blending normal maps is a bit trickier... you can't just blend the normals like you would a color (it produces incorrect results). Take a look at this paper from GDC08, which talks about how to do it properly. The only issue is that you'd need to also have a heightmap per layer.

Edit: Although you could do the masking sort of thing which Tom mentions, I suppose.

#23 @Ross: A simple approach would be to compare the two normal pixels, and take whichever is more dominant - instead of a lerp. But I'm sure there are better solutions. I'll check that paper out, thanks!

#24 Blending normal maps rarely works as well as you would expect, its works for for constructive/destructive interference (ala water) and adding detail normals but for combining two surfaces, not so well.
It because the parameter space of correct normal is much less than the parameter space of correct colours. When combining colours, the combination can be anywhere in the colour cube, however for normal its can only be on the unit sphere iso-surface within that cube (after normalisation) which means there is less variance available and so normals tend to become 'muddy'.
Not that its a good technique to have in the tool kit, just never looks as good as I'd hoped whenever i've tried it. :-/

#25 @Dean: While you are right about parameter spaces, the method I mean works really well with my cliffs - material accumulation is partially based on this. Here's a video of what I mean.

#26 @Konrad: Look cool, yeah when I started writing that post was before you mentioned the selection method so was just refering to lerp blends. The selection system appears to work really well in that video :)

#27 @Konrad - Off topic I know but was looking at the video you mentioned on material accumulation and wondered what software your using for Video Capture in the editors? I usually use FRAPS but it really doesn't appear to work once you open up the World Editor in TGEA.

#28 @Andy - I use fraps too, but I start it after I enter the World Editor - that way it will work as long as you stay in the editor.