--- ray/doc/ray.1	2016/05/25 18:52:45	1.29
+++ ray/doc/ray.1	2017/04/08 00:09:35	1.31
@@ -1,8 +1,8 @@
-.\" RCSid "$Id: ray.1,v 1.29 2016/05/25 18:52:45 greg Exp $"
+.\" RCSid "$Id: ray.1,v 1.31 2017/04/08 00:09:35 greg Exp $"
 .\" Print using the -ms macro package
-.DA 09/18/2015
+.DA 07/10/2016
 .LP
-.tl """Copyright \(co 2015 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
@@ -946,8 +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