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Comparing ray/doc/ray.1 (file contents):
Revision 1.10 by greg, Tue Oct 17 21:52:43 2006 UTC vs.
Revision 1.18 by greg, Fri Feb 18 00:40:25 2011 UTC

# Line 1 | Line 1
1   .\" RCSid "$Id"
2   .\" Print using the -ms macro package
3 < .DA 1/20/99
3 > .DA 2/17/2011
4   .LP
5 < .tl """Copyright \(co 2006 Regents, University of California
5 > .tl """Copyright \(co 2011 Regents, University of California
6   .sp 2
7   .TL
8   The
# Line 491 | Line 491 | a perfectly scattering medium (no absorption).
491   The scattering eccentricity parameter will likewise override the global
492   setting if it is present.
493   Scattering eccentricity indicates how much scattered light favors the
494 < forward direction, as fit by the Heyney-Greenstein function:
494 > forward direction, as fit by the Henyey-Greenstein function:
495   .DS
496   P(theta) = (1 - g*g) / (1 + g*g - 2*g*cos(theta))^1.5
497   .DE
# Line 865 | Line 865 | mod transdata id
865   6+ red green blue rspec trans tspec A7 ..
866   .DE
867   .LP
868 + .UL BSDF
869 + .PP
870 + The BSDF material type loads an XML (eXtensible Markup Language)
871 + file describing a bidirectional scattering distribution function.
872 +
873 + Real arguments to this material may define additional
874 + diffuse components that augment the BSDF data.
875 + String arguments are used to define thickness for hidden
876 + objects and the "up" orientation for the material.
877 + .DS
878 + mod BSDF id
879 + 6+ thick BSDFfile ux uy uz funcfile transform
880 + 0
881 + 0|3|6|9
882 +     rfdif gfdif bfdif
883 +     rbdif gbdif bbdif
884 +     rtdif gtdif btdif
885 + .DE
886 + The first string argument is a "thickness" parameter that is useful
887 + for hiding detail geometry for transmitting systems, e.g.,
888 + complex fenestration.
889 + If a view or shadow ray hits a BSDF surface with non-zero specular transmission
890 + and positive thickness, the ray will pass directly through with no
891 + reflection or transmission due to the BSDF.
892 + Similar to the illum type, this permits direct viewing and
893 + shadow testing of complex geometry.
894 + In contrast, a scattered ray will use the BSDF transmission,
895 + offsetting transmitted sample rays by the thickness amount
896 + to avoid any intervening geometry.
897 + In this manner, BSDF surfaces may act as simplified stand-ins for detailed
898 + system geometry, which may still be present and visible in the simulation.
899 + If the BSDF has back-side reflection data, a parallel surface should be
900 + specified slightly less than the given thickness away from the front surface
901 + to enclose the system geometry on both sides.
902 + A zero thickness implies that the BSDF geomtery is all there is, and
903 + thickness is ignored if there is no transmitted component, or transmission is
904 + purely diffuse.
905 + .LP
906 + The second string argument is the name of the BSDF file, which is
907 + found in the usual auxiliary locations.
908 + The following three string parameters name variables for an "up" vector,
909 + which together with the surface normal, define the
910 + local coordinate system that orients the BSDF.
911 + These variables, along with the thickness, are defined in a function
912 + file given as the next string argument.
913 + An optional transform is used to scale the thickness and reorient the up vector.
914 + .LP
915 + If no real arguments are given, the BSDF is used by itself to determine
916 + reflection and transmission.
917 + If there are at least 3 real arguments, the first triplet is an
918 + additional diffuse reflectance for the front side.
919 + At least 6 real arguments adds diffuse reflectance to the rear side of the surface.
920 + If there are 9 real arguments, the final triplet will be taken as an additional
921 + diffuse transmittance.
922 + All diffuse components as well as the non-diffuse transmission are
923 + modified by patterns applied to this material.
924 + The non-diffuse reflection from either side are unaffected.
925 + Textures perturb the effective surface normal in the usual way.
926 + .LP
927 + The surface normal of this type is not altered to face the incoming ray,
928 + so the front and back BSDF reflections may differ.
929 + (Transmission is identical front-to-back by physical law.)\0
930 + If back visibility is turned off during rendering and there is no
931 + transmission or back-side reflection, only then the surface will be
932 + invisible from behind.
933 + Unlike other data-driven material types, the BSDF type is fully
934 + supported and all parts of the distribution are properly sampled.
935 + .LP
936   .UL Antimatter
937   .PP
938   Antimatter is a material that can "subtract" volumes from other volumes.
# Line 1109 | Line 1177 | which serves as a form of opacity control when used wi
1177   Vname is the coefficient defined in funcfile that determines the influence
1178   of foreground.
1179   The background coefficient is always (1-vname).
1112 – Since the references are not resolved until runtime, the last
1113 – definitions of the modifier id's will be used.
1114 – This can result in modifier loops, which are detected by the
1115 – renderer.
1180   .LP
1181   .UL Mixdata
1182   .PP
# Line 1239 | Line 1303 | If no file is needed by a given primitive because all
1303   variables are global, a period (`.') can be given in
1304   place of the file name.
1305   It is also possible to give an expression instead of a straight
1306 < variable name in a scene file, although such expressions should
1307 < be kept simple if possible.
1244 < Also, functions (requiring parameters)
1306 > variable name in a scene file.
1307 > Functions (requiring parameters)
1308   must be given as names and not as expressions.
1309   .PP
1310   Constant expressions are used as an optimization in function
# Line 1405 | Line 1468 | converts a picture to and from simpler formats.
1468   Pictures may be displayed directly under X11 using the program
1469   .I ximage,
1470   or converted a standard image format.
1471 < .I Ra_avs
1472 < converts to and from AVS image format.
1410 < .I Ra_pict
1411 < converts to Macintosh 32-bit PICT2 format.
1471 > .I Ra_bmp
1472 > converts to and from Microsoft Bitmap images.
1473   .I Ra_ppm
1474   converts to and from Poskanzer Portable Pixmap formats.
1414 – .I Ra_pr
1415 – converts to and from Sun 8-bit rasterfile format.
1416 – .I Ra_pr24
1417 – converts to and from Sun 24-bit rasterfile format.
1475   .I Ra_ps
1476   converts to PostScript color and greyscale formats.
1477   .I Ra_rgbe
# Line 1433 | Line 1490 | License
1490   .DS
1491   The Radiance Software License, Version 1.0
1492  
1493 < Copyright (c) 1990 - 2002 The Regents of the University of California,
1493 > Copyright (c) 1990 - 2008 The Regents of the University of California,
1494   through Lawrence Berkeley National Laboratory.   All rights reserved.
1495  
1496   Redistribution and use in source and binary forms, with or without

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