--- ray/doc/ray.html 2023/12/12 20:25:22 1.37
+++ ray/doc/ray.html 2024/12/09 19:21:38 1.39
@@ -1,5 +1,5 @@
-
+
The RADIANCE 6.0 Synthetic Imaging System
@@ -834,6 +834,62 @@ unless the line integrals consider enclosed geometry.
<p>
<dt>
+ <a NAME="WGMDfunc">
+ <b>WGMDfunc</b>
+ </a>
+
+<dd>
+ WGMDfunc is a more programmable version of <a HREF="#Trans2">trans2</a>,
+ 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 previous ones beside Ashik2.)
+ The specification of this material is given below.
+<pre>
+ 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 ..
+</pre>
+
+The sum of specular reflectance (<I>rs</I>), specular transmittance (<I>ts</I>),
+diffuse reflectance (<I>rfdif gfdif bfdif</I> for front and <I>rbdif gbdif bbdif</I> for back)
+and diffuse transmittance (<I>rtdif gtdif btdif</I>) should be less than 1 for each
+channel.
+
+<p>
+
+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</I> modifier is used for specular reflectance.
+If "void" is given for <I>rs_mod</I>,
+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</I>, which also has its own independent roughness expressions.
+Finally, the diffuse transmittance modifier is given as
+<I>td_mod</I>, which may also be "void" or "inherit".
+Note that any spectra or color for specular components must be
+carried by the named modifier(s).
+
+<p>
+
+The main advantage to this material over
+<a HREF="#BRTDfunc">BRTDfunc</a> and
+other programmable types described below is that the specular sampling is
+well-defined, so that all components are fully computed.
+
+<p>
+
+<dt>
<a NAME="Dielectric">
<b>Dielectric</b>
</a>
@@ -1552,6 +1608,61 @@ or:
This function is fed a wavelenth sample
between nmA and nmB as its only argument,
and it returns the corresponding spectral intensity.
+
+<dt>
+ <a NAME="Specdata">
+ <b>Specdata</b>
+ </a>
+
+<dd>
+ Specdata is like brightdata and colordata, but with more
+ than 3 specular samples.
+
+<pre>
+ mod specdata id
+ 3+n+
+ func datafile
+ funcfile x1 x2 .. xn transform
+ 0
+ m A1 A2 .. Am
+</pre>
+
+<p>
+ 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.
+
+<dt>
+ <a NAME="Specpict">
+ <b>Specpict</b>
+ </a>
+
+<dd>
+ 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.
+
+<pre>
+ mod specpict id
+ 5+
+ func specfile
+ funcfile u v transform
+ 0
+ m A1 A2 .. Am
+</pre>
+
+<p>
+ 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".
</dl>