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# ctrl.studio, Jan 24 2006
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# ctrl_xshading
# shader plugin for softimage|xsi
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# revisions (last mod, April 25 2006)::
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# (v1.0) xsi pubblic release
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a simple shader that can include/exclude lights. all xsi features still supported
like light inclusive/exclusive and diffuse/specular toggle, pass.channels, ambience 
from interface.

lambert and orenayar support for diffuse; phong, torrance-sparrow, trowbridge-reitz
and fresnel for speculars. when in lambert mode the roughness acts like a simple 
gamma factor.. set to 1.0 to have the usual lambert behaviour. it can also be tweaked
indipendetly when in photon mode. irradiance can be disabled to work perfectly together
with ctrl.irradiance for advanced irradiance computation. the diffuse parameter acts
like a multiplier for the diffuse layer.