I have on object with multiple UV sets and I'd like to use the second UV for the direction of an anisotropic specular. I can't seem to find a way to get the derivs / bump_x_list data for a specific UV set. Is it possible?
Cheers, Szabolcs
freds
[ Editor ]
Hi Szabolcs,
looks like you can do this,
In your mia_materials Anisotropy tab you should have a 'Channel' attribute. This lets you point to other UV sets than the default one.
0(zero) is the default UV set, 1 is the first UV set you added yourself etc.
If you hover your mouse pointer over the 'Channel' attribute in the Attibute Editor it says, "Anisotropic base angle comes from the U direction of the chosen texture space."
Other values you can use, anisotropy_channel can also have the following "special" values:
- -1: the base rotation follows the local object coordinate system.
- -2: the base rotation follows the bump basis vectors
- -3: the base rotation follows the surface derivatives
- -4: the base rotation follows a vector placed in state>tex prior to calling mia_material
(from http://toi.bk.tudelft.nl/maya/help/docs/Maya2008/en_US/ArchGuide/arch_mtl.html)
Also have a look at these two threads for more info about MR and UV sets, http://forum.mentalimages.com/showthread.php?t=3906 http://forum.mentalimages.com/showthread.php?t=5695
cheers fred
NN comments
Horvatth Szabolcs
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Hi Fred,
Thanks for your response! Its great that its handled automatically in miamaterial, but I’d like to get / the basis vectors in a custom shader. I could calculate them for myself using data provided by mitri_vectors but I would have preferred using a built-in solution.
Cheers, Szabolcs