--- ray/doc/ray.1	2011/06/21 23:58:00	1.20
+++ ray/doc/ray.1	2017/04/08 00:09:35	1.31
@@ -1,8 +1,8 @@
-.\" RCSid "$Id"
+.\" RCSid "$Id: ray.1,v 1.31 2017/04/08 00:09:35 greg Exp $"
 .\" Print using the -ms macro package
-.DA 2/17/2011
+.DA 07/10/2016
 .LP
-.tl """Copyright \(co 2011 Regents, University of California
+.tl """Copyright \(co 2016 Regents, University of California
 .sp 2
 .TL
 The
@@ -622,6 +622,21 @@ mod trans2 id
 8 red green blue spec urough vrough trans tspec
 .DE
 .LP
+.UL Ashik2
+.PP
+Ashik2 is the anisotropic reflectance model by Ashikhmin & Shirley.
+The string arguments are the same as for plastic2, but the real
+arguments have additional flexibility to specify the specular color.
+Also, rather than roughness, specular power is used, which has no
+physical meaning other than larger numbers are equivalent to a smoother
+surface.
+.DS
+mod ashik2 id
+4+ ux uy uz funcfile transform
+0
+8 dred dgrn dblu sred sgrn sblu u-power v-power
+.DE
+.LP
 .UL Dielectric
 .PP
 A dielectric material is transparent, and it refracts light
@@ -899,9 +914,7 @@ a parallel BSDF surface may be
 placed slightly less than the given thickness away from the front surface
 to enclose the complex geometry on both sides.
 The sign of the thickness is important, as it indicates whether the
-proxied geometry is behind the.
-.I BSDF
-surface (when thickness is positive)
+proxied geometry is behind the BSDF surface (when thickness is positive)
 or in front (when thickness is negative).
 .LP
 The second string argument is the name of the BSDF file, which is
@@ -948,8 +961,10 @@ N mod1 mod2 .. modN
 The first modifier will also be used to shade the area leaving the
 antimatter volume and entering the regular volume.
 If mod1 is void, the antimatter volume is completely invisible.
-Antimatter does not work properly with the material type "trans",
-and multiple antimatter surfaces should be disjoint.
+If shading is desired at antimatter surfaces, it is important
+that the related volumes are closed with outward-facing normals.
+Antimatter surfaces should not intersect with other antimatter boundaries,
+and it is unwise to use the same modifier in nested antimatter volumes.
 The viewpoint must be outside all volumes concerned for a correct
 rendering.
 .NH 3
@@ -1157,6 +1172,7 @@ between 0.1 (for tightly spaced characters) and 0.3 (f
 Mixtures
 .PP
 A mixture is a blend of one or more materials or textures and patterns.
+Blended materials should not be light source types or virtual source types.
 The basic types are given below.
 .LP
 .UL Mixfunc
@@ -1553,6 +1569,25 @@ the Ecole Polytechnique Federale de Lausanne (EPFL Uni
 in Lausanne, Switzerland.
 .NH 1
 References
+.LP
+Ward, G., M. Kurt & N. Bonneel,
+``Reducing Anisotropic BSDF Measurement to Common Practice,''
+.I Workshop on Material Appearance Modeling,
+2014.
+.LP
+McNeil, A., C.J. Jonsson, D. Appelfeld, G. Ward, E.S. Lee,
+``A validation of a ray-tracing tool used to generate
+bi-directional scattering distribution functions for
+complex fenestration systems,''
+.I "Solar Energy",
+98, 404-14, November 2013.
+.LP
+Ward, G., R. Mistrick, E.S. Lee, A. McNeil, J. Jonsson,
+``Simulating the Daylight Performance of Complex Fenestration Systems
+Using Bidirectional Scattering Distribution Functions within Radiance,''
+.I "Leukos",
+7(4),
+April 2011.
 .LP
 Cater, K., A. Chalmers, G. Ward,
 ``Detail to Attention: Exploiting Visual Tasks for Selective Rendering,''