--- ray/doc/ray.1	2023/11/15 18:28:09	1.41
+++ ray/doc/ray.1	2024/12/09 19:21:38	1.47
@@ -1,8 +1,8 @@
-.\" RCSid "$Id: ray.1,v 1.41 2023/11/15 18:28:09 greg Exp $"
+.\" RCSid "$Id: ray.1,v 1.47 2024/12/09 19:21:38 greg Exp $"
 .\" Print using the -ms macro package
-.DA 11/13/2023
+.DA 12/09/2024
 .LP
-.tl """Copyright \(co 2023 Regents, University of California
+.tl """Copyright \(co 2024 Regents, University of California
 .sp 2
 .TL
 The
@@ -639,6 +639,64 @@ mod ashik2 id
 8 dred dgrn dblu sred sgrn sblu u-power v-power
 .DE
 .LP
+.UL WGMDfunc
+.PP
+WGMDfunc is a more programmable version of trans2,
+with separate modifier paths and variables to control each component.
+(WGMD stands for Ward-Geisler-Moroder-Duer, which is the basis for
+this empirical model, similar to the previous ones beside Ashik2.)\0
+The specification of this material is given below.
+.DS
+mod WGMDfunc id
+13+ rs_mod  rs  rs_urough rs_vrough
+    ts_mod  ts  ts_urough ts_vrough
+    td_mod
+    ux uy uz  funcfile  transform
+0
+9+  rfdif gfdif bfdif
+    rbdif gbdif bbdif
+    rtdif gtdif btdif
+    A10 ..
+.DE
+The sum of specular reflectance (
+.I rs
+), specular transmittance (
+.I ts
+), diffuse reflectance (
+.I "rfdif gfdif bfdif"
+for front and
+.I "rbdif gbdif bbdif"
+for back)
+and diffuse transmittance (
+.I "rtdif gtdif btdif"
+) should be less than 1 for each
+channel.
+.PP
+Unique to this material, separate modifier channels are
+provided for each component.
+The main modifier is used on the diffuse reflectance, both
+front and back.
+The
+.I rs_mod
+modifier is used for specular reflectance.
+If "void" is given for
+.I rs_mod,
+then the specular reflection color will be white.
+The special "inherit" keyword may also be given, in which case
+specular reflectance will share the main modifier.
+This behavior is replicated for the specular transmittance modifier
+.I ts_mod,
+which has its own independent roughness expressions.
+Finally, the diffuse transmittance modifier is given as
+.I td_mod,
+which may also be "void" or "inherit".
+Note that any spectra or color for specular components must be
+carried by the named modifier(s).
+.PP
+The main advantage to this material over BRTDfunc and
+other programmable types described below is that the specular sampling is
+well-defined, so that all components are fully computed.
+.LP
 .UL Dielectric
 .PP
 A dielectric material is transparent, and it refracts light
@@ -1207,14 +1265,12 @@ mod spectrum id
 0
 5+ nmA nmB s1 s2 .. sN
 .DE
-The first two real arguments indicate the limits of the covered
+The first two real arguments indicate the extrema of the
 spectral range in nanometers.
-Subsequent real values correspond to multipliers in each wavelength band,
-where the first band goes from nmA to nmA+(nmB-nmA)/N, and N is the
-number of bands (i.e., the number of real arguments minus 2).
-The nmA wavelength may be greater or less than the nmB wavelength,
-but they may not be equal, and their ordering must correspond to
-the ordering of the spectral values.
+Subsequent real values correspond to multipliers at each wavelength.
+The nmA wavelength may be greater or less than nmB,
+but they may not be equal, and their ordering matches
+the order of the spectral values.
 A minimum of 3 values must be given, which would act
 more or less the same as a constant RGB multiplier.
 As with RGB values, spectral quantities normally range between 0
@@ -1251,16 +1307,57 @@ The specfunc primitive offers dynamic control over a s
 pattern, similar to the colorfunc type.
 .DS
 mod specfunc id
-2+ sval funcfile transform
+2+ sfunc funcfile transform
 0
 2+ nmA nmB A3 ..
 .DE
 Like the spectrum primitive, the wavelength range is specified
 in the first two real arguments, and additional real values are
-accessible to the sval function.
+set in the evaluation context.
 This function is fed a wavelenth sample
 between nmA and nmB as its only argument,
 and it returns the corresponding spectral intensity.
+.LP
+.UL Specdata
+.PP
+Specdata is like brightdata and colordata, but with more
+than 3 specular samples.
+.DS
+mod specdata id
+3+n+
+	func datafile
+	funcfile x1 x2 .. xn transform
+0
+m A1 A2 .. Am
+.DE
+The data file must have one more dimension than the coordinate
+variable count, as this final dimension corresponds to the covered
+spectrum.
+The starting and ending wavelengths are specified in "datafile"
+as well as the number of spectral samples.
+The function "func" will be called with two parameters, the
+interpolated spectral value for the current coordinate and the
+associated wavelength.
+If the spectrum is broken into 12 components, then 12 calls
+will be made to "func" for the relevant ray evaluation.
+.LP
+.UL Specpict
+.PP
+Specpict is a special case of specdata, where the pattern is
+a hyperspectral image stored in the common-exponent file format.
+The dimensions of the image data are determined by the picture
+just as with the colorpict primitive.
+.DS
+mod specpict id
+5+
+	func specfile
+	funcfile u v transform
+0
+m A1 A2 .. Am
+.DE
+The function "func" is called with the interpolated pixel value
+and the wavelength sample in nanometers, the same as specdata,
+with as many calls made as there are components in "specfile".
 .NH 3
 Mixtures
 .PP