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.\" RCSid "$Id$" |
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.\" Print using the -ms macro package |
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.DA 11/13/2023 |
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.DA 12/09/2024 |
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.LP |
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.tl """Copyright \(co 2023 Regents, University of California |
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.tl """Copyright \(co 2024 Regents, University of California |
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.sp 2 |
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.TL |
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The |
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0 |
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8 dred dgrn dblu sred sgrn sblu u-power v-power |
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.DE |
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.LP |
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.UL WGMDfunc |
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.PP |
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WGMDfunc is a more programmable version of trans2, |
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with separate modifier paths and variables to control each component. |
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(WGMD stands for Ward-Geisler-Moroder-Duer, which is the basis for |
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this empirical model, similar to the previous ones beside Ashik2.)\0 |
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The specification of this material is given below. |
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.DS |
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mod WGMDfunc id |
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13+ rs_mod rs rs_urough rs_vrough |
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ts_mod ts ts_urough ts_vrough |
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td_mod |
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ux uy uz funcfile transform |
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0 |
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9+ rfdif gfdif bfdif |
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rbdif gbdif bbdif |
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rtdif gtdif btdif |
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A10 .. |
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.DE |
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The sum of specular reflectance ( |
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.I rs |
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), specular transmittance ( |
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.I ts |
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), diffuse reflectance ( |
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.I "rfdif gfdif bfdif" |
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for front and |
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.I "rbdif gbdif bbdif" |
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for back) |
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and diffuse transmittance ( |
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.I "rtdif gtdif btdif" |
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) should be less than 1 for each |
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channel. |
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.PP |
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Unique to this material, separate modifier channels are |
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provided for each component. |
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The main modifier is used on the diffuse reflectance, both |
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front and back. |
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The |
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.I rs_mod |
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modifier is used for specular reflectance. |
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If "void" is given for |
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.I rs_mod, |
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then the specular reflection color will be white. |
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The special "inherit" keyword may also be given, in which case |
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specular reflectance will share the main modifier. |
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This behavior is replicated for the specular transmittance modifier |
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.I ts_mod, |
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which has its own independent roughness expressions. |
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Finally, the diffuse transmittance modifier is given as |
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.I td_mod, |
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which may also be "void" or "inherit". |
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Note that any spectra or color for specular components must be |
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carried by the named modifier(s). |
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.PP |
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The main advantage to this material over BRTDfunc and |
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other programmable types described below is that the specular sampling is |
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well-defined, so that all components are fully computed. |
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.LP |
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.UL Dielectric |
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.PP |
