--- ray/doc/ray.1	2023/11/17 20:02:07	1.43
+++ ray/doc/ray.1	2024/12/09 19:21:38	1.47
@@ -1,8 +1,8 @@
-.\" RCSid "$Id: ray.1,v 1.43 2023/11/17 20:02:07 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
@@ -1209,7 +1267,7 @@ mod spectrum id
 .DE
 The first two real arguments indicate the extrema of the
 spectral range in nanometers.
-Subsequent real values correspond to multipliers in at each wavelength.
+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.
@@ -1249,16 +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