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johnnyreno
03-27-2006, 06:14 PM
fom my post on the lamrug site:

Hello,

I'm trying to understand if I can apply a different texture to faces created with a displacement map. Consider this basic eaxmple:

In the scene there exists a square poly plane with 3x3 subdivisions for 9 total faces which has been textured with a numbered grid with a number that correspondes to each face 1-9.. If I displace the center face (# 5) 1 unit, is there a way to map different textures to the new tangent faces connected between (2,5), (4,5), (5,6), and (5,8).

Perhaps a brief explanation of what is actualy happening in terms of geometry paramaterization and uv mapping during displacemet, inside mr would shed some light...

Thank You.

Gal
03-28-2006, 09:04 PM
hmm if i understand what you mean, you cant.
because all it does is push existing geometry and tesselates it to whatever fine level you pick. it does not "extrude" new polys around the face u pushed in. if u want to texture that area u need to texture your predisplaced object with "distorted" texture placement in the area where it will be pushed down so when it does push down they will be in right ratio.
i'd say you could uv map your predispalced object then convert your object with displacement into polys under mental ray menu and then create your texture map based off that shape.. then apply this texture to the predisplaced original object. since they have the same exact uvs it should work BUT i dont know if mental ray will rebuild the object when you bake displacements into polys(if it doesnt rebuild but only splits it's fine for you, but if it does rebuild and renumber vertex order, which i think it will, then you can do what i just said since u will have to re-uv your displaced object). and sadly there are no functions that transfer texture maps btwn objects with different polycount/vertex order. you could try sampler in 7 for that but i am not sure it will work right.

johnnyreno
03-28-2006, 11:03 PM
Thanks for your input, you're pretty close....Initially, I pursued a similar technique to what you described, but ultimately, I'm driving the displacement with an animated texture sequence, so this is not something that I can do for every frame. I'm testing some other ideas and will post anything that looks promising, but other suggestions are eagerly welcome.

Thanks again.

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03-28-2006, 11:03 PM
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