@@ -82,7 +83,7 @@ The diagram in Figure 1 shows the flow between program (ovals). The central program is rpict, which produces a picture from a scene description. -Rview is a variation of rpict that computes and displays images +Rvu is a variation of rpict that computes and displays images interactively, and rtrace computes single ray values. Other programs (not shown) connect many of these elements together, such as the executive programs @@ -147,6 +148,8 @@ It is stored as ASCII text, with the following bas ... +
+ A comment line begins with a pound sign, `#'.
@@ -393,6 +396,7 @@ The basic types are given below. 0 +
If the modifier is "void", then surfaces will use the modifiers given in the original description. Otherwise, the modifier specified is used in their place. @@ -437,6 +441,8 @@ The basic types are given below. 0 +
+ If the modifier is "void", then surfaces will use the modifiers given in the original mesh description. Otherwise, the modifier specified is used in their place. @@ -531,6 +537,7 @@ A material defines the way light interacts with a sur 4 red green blue maxrad +
If maxrad is zero, then the surface will never be tested for shadow, although it may participate in an interreflection calculation. If maxrad is negative, then the surface will never contribute to scene illumination. Glow sources will never illuminate objects on the other side of an illum surface. @@ -564,7 +571,7 @@ A material defines the way light interacts with a sur
+The mirror material type reflects light sources only from the front side +of a surface, regardless of any alternate material. +If virtual source generation is desired on both sides, two coincident +surfaces with opposite normal orientations may be employed to achieve +this effect. +The reflectance and alternate material type may be +different for the overlapped surfaces, +and the two sides will behave accordingly. + +
+
@@ -602,6 +629,8 @@ This is only appropriate if the surface hides other (m
n A1 A2 .. An
++ The new direction variables dx, dy and dz need not produce a normalized vector. For convenience, the variables DxA, DyA and DzA are defined as the normalized direction to the target light source. See section 2.2.1 on function files for further information. @@ -645,6 +674,7 @@ This is only appropriate if the surface hides other (m 3 source1 mirror1>source10 mirror2>mirror1>source3 +
Normally, only one source is given per mist material, and there is an upper limit of 32 to the total number of active scattering sources. The extinction coefficient, if given, is added the the global @@ -659,12 +689,14 @@ a perfectly scattering medium (no absorption). The scattering eccentricity parameter will likewise override the global setting if it is present. Scattering eccentricity indicates how much scattered light favors the -forward direction, as fit by the Heyney-Greenstein function: +forward direction, as fit by the Henyey-Greenstein function:
P(theta) = (1 - g*g) / (1 + g*g - 2*g*cos(theta))^1.5+
+ A perfectly isotropic scattering medium has a g parameter of 0, and a highly directional material has a g parameter close to 1. Fits to the g parameter may be found along with typical extinction @@ -679,6 +711,8 @@ cloud types in USGS meteorological tables. 0|3|6|7 [ rext gext bext [ ralb galb balb [ g ] ] ] +
+ There are two usual uses of the mist type. One is to surround a beam from a spotlight or laser so that it is visible during rendering. @@ -797,7 +831,8 @@ unless the line integrals consider enclosed geometry.
mod trans2 id
@@ -809,6 +844,87 @@ unless the line integrals consider enclosed geometry.
+ mod ashik2 id + 4+ ux uy uz funcfile transform + 0 + 8 dred dgrn dblu sred sgrn sblu u-power v-power ++ +
+ +
+ 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 .. ++ +
+ +The sum of specular reflectance (rs), specular transmittance (ts), +diffuse reflectance (rfdif gfdif bfdif for front and rbdif gbdif bbdif for back) +and diffuse transmittance (rtdif gtdif btdif) should be less than 1 for each +channel. + +
+ +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 rs_mod modifier is used for specular reflectance. +If "void" is given for 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 +ts_mod, which also has its own independent roughness expressions. +Finally, the diffuse transmittance modifier is given as +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). + +
+ +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. + +
+ +
+ Standard 88% transmittance glass has a transmissivity of 0.96. (A pattern modifying glass will affect the transmissivity.) If a fourth real argument is given, it is interpreted as the index of refraction to use instead of 1.52. @@ -900,6 +1018,8 @@ unless the line integrals consider enclosed geometry. 4+ red green blue spec A5 .. +
+ The function refl takes four arguments, the x, y and z direction towards the incident light, and the solid angle subtended by the source. @@ -941,6 +1061,8 @@ unless the line integrals consider enclosed geometry. 6+ red green blue rspec trans tspec A7 .. +
+ Where trans is the total light transmitted and tspec is the non-Lambertian fraction of transmitted light. The function brtd should integrate to 1 over each projected hemisphere. @@ -968,6 +1090,8 @@ unless the line integrals consider enclosed geometry. A10 .. +
+ The variables rrefl, grefl and brefl specify the color coefficients for the ideal specular (mirror) reflection of the surface. The variables rtrns, gtrns and btrns specify the color coefficients for the ideal specular transmission. The functions rbrtd, gbrtd and bbrtd take the direction to the incident light (and its solid angle) and @@ -1012,6 +1136,8 @@ unless the line integrals consider enclosed geometry. 4+ red green blue spec A5 .. +
+ The coordinate indices (x1, x2, etc.) are themselves functions of the x, y and z direction to the incident light, plus the solid angle subtended by the light source (usually ignored). The data function (func) takes five variables, the @@ -1053,6 +1179,116 @@ unless the line integrals consider enclosed geometry.
+ mod BSDF id + 6+ thick BSDFfile ux uy uz funcfile transform + 0 + 0|3|6|9 + rfdif gfdif bfdif + rbdif gbdif bbdif + rtdif gtdif btdif ++ +
+ The first string argument is a "thickness" parameter that may be used + to hide detail geometry being proxied by an aggregate BSDF material. + If a view or shadow ray hits a BSDF proxy with non-zero thickness, + it will pass directly through as if the surface were not there. + Similar to the illum type, this permits direct viewing and + shadow testing of complex geometry. + The BSDF is used when a scattered (indirect) ray hits the surface, + and any transmitted sample rays will be offset by the thickness amount + to avoid the hidden geometry and gather samples from the other side. + In this manner, BSDF surfaces can improve the results for indirect + scattering from complex systems without sacrificing appearance or + shadow accuracy. + If the BSDF has transmission and back-side reflection data, + 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 BSDF + surface (when thickness is positive) or in front (when + thickness is negative). +
+ The second string argument is the name of the BSDF file, + which is found in the usual auxiliary locations. The + following three string parameters name variables for an + "up" vector, which together with the surface + normal, define the local coordinate system that orients the + BSDF. These variables, along with the thickness, are defined + in a function file given as the next string argument. An + optional transform is used to scale the thickness and + reorient the up vector. +
+ If no real arguments are given, the BSDF is used by itself + to determine reflection and transmission. If there are at + least 3 real arguments, the first triplet is an additional + diffuse reflectance for the front side. At least 6 real + arguments adds diffuse reflectance to the rear side of the + surface. If there are 9 real arguments, the final triplet + will be taken as an additional diffuse transmittance. All + diffuse components as well as the non-diffuse transmission + are modified by patterns applied to this material. The + non-diffuse reflection from either side are unaffected. + Textures perturb the effective surface normal in the usual + way. +
+ The surface normal of this type is not altered to face the + incoming ray, so the front and back BSDF reflections may + differ. (Transmission is identical front-to-back by physical + law.) If back visibility is turned off during rendering and + there is no transmission or back-side reflection, only then + the surface will be invisible from behind. Unlike other + data-driven material types, the BSDF type is fully supported + and all parts of the distribution are properly sampled. +
+ +
+ mod aBSDF id + 5+ BSDFfile ux uy uz funcfile transform + 0 + 0|3|6|9 + rfdif gfdif bfdif + rbdif gbdif bbdif + rtdif gtdif btdif ++ +
+ If a material has no specular transmitted component, it is + much better to use the BSDF type with a zero thickness + than to use aBSDF. +
+ +
+ 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", @@ -1122,6 +1360,8 @@ A texture is a perturbation of the surface normal, an n A1 A2 .. An +
+
@@ -1261,6 +1501,8 @@ A colorfunc is a procedurally defined color pattern [spacing] +
+ or:
@@ -1298,6 +1540,8 @@ or:
[spacing]
++ or:
@@ -1326,6 +1570,153 @@ or: A section of text meant to depict a picture, perhaps using a special purpose font such as hexbit4x1.fnt, calls for uniform spacing. Reasonable magnitudes for proportional spacing are between 0.1 (for tightly spaced characters) and 0.3 (for wide spacing). ++ +
+ mod spectrum id + 0 + 0 + 5+ nmA nmB s1 s2 .. sN ++ +
+ The first two real arguments indicate the extrema of the + spectral range in nanometers. + 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. + A minimum of 3 values must be given, which would act + more or less the same as a constant RGB multiplier. + As with RGB values, spectral quantities normally range between 0 + and 1 at each wavelength, or average to 1.0 against a standard + sensitivity functions such as V(lambda). + The best results obtain when the spectral range and number + of samples match rendering options, though resampling will handle + any differences, zero-filling wavelenths outside the nmA to nmB + range. + A warning will be issued if the given wavelength range does not + adequately cover the visible spectrum. + +
+ +
+ mod specfile id + 1 datafile + 0 + 0 ++ +
+ As with the spectrum type, rendering wavelengths outside the defined + range will be zero-filled. + Unlike the spectrum type, the file may contain non-uniform samples. + +
+ +
+ mod specfunc id + 2+ sfunc funcfile transform + 0 + 2+ nmA nmB A3 .. ++ +
+ Like the spectrum primitive, the wavelength range is specified + in the first two real arguments, and additional real values are + 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. + +
+ mod specdata id + 3+n+ + func datafile + funcfile x1 x2 .. xn transform + 0 + m A1 A2 .. Am ++ +
+ 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. + +
+ mod specpict id + 5+ + func specfile + funcfile u v transform + 0 + m A1 A2 .. Am ++ +
+ 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". +
@@ -1336,6 +1727,7 @@ or: 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.
@@ -1357,6 +1749,8 @@ A mixfunc mixes two modifiers procedurally. It i n A1 A2 .. An +
+ Foreground and background are modifier names that must be defined earlier in the scene description. If one of these is a material, then @@ -1365,8 +1759,6 @@ A mixfunc mixes two modifiers procedurally. It i which serves as a form of opacity control when used with a material.) Vname is the coefficient defined in funcfile that determines the influence of foreground. The background coefficient is always (1-vname). - Since the references are not resolved until run-time, the last definitions of the modifier id's will be used. - This can result in modifier loops, which are detected by the renderer.
@@ -1387,6 +1779,8 @@ A mixfunc mixes two modifiers procedurally. It i m A1 A2 .. Am +
+
+ or:
@@ -1447,6 +1842,8 @@ or:
[spacing]
++
@@ -1491,6 +1888,8 @@ An example function file is given below: cfunc(x) : 10*x / sqrt(x) ; +
+ Many variables and functions are already defined by the program, and they are listed in the file rayinit.cal. The following variables are particularly important: @@ -1505,12 +1904,16 @@ The following variables are particularly important: arg(i) - i'th real argument +
+ For mesh objects, the local surface coordinates are available:
Lu, Lv - local (u,v) coordinates
++ For BRDF types, the following variables are defined as well:
@@ -1519,6 +1922,8 @@ For BRDF types, the following variables are defined as
CrP, CgP, CbP - perturbed material color
++ A unique context is set up for each file so that the same variable may appear in different function files without conflict. @@ -1528,10 +1933,8 @@ If no file is needed by a given primitive because all the required variables are global, a period (`.') can be given in place of the file name. It is also possible to give an expression instead -of a straight variable name in a scene file, -although such expressions should be kept -simple if possible. -Also, functions (requiring parameters) must be given +of a straight variable name in a scene file. +Functions (requiring parameters) must be given as names and not as expressions.
@@ -1575,6 +1978,8 @@ The basic data file format is as follows: DATA, later dimensions changing faster. +
+ N is the number of dimensions. For each dimension, the beginning and ending coordinate values and the dimension size is given. Alternatively, individual coordinate values can be given when the points are not evenly spaced. @@ -1603,6 +2008,8 @@ All numbers are decimal integers: ... +
+ The ASCII codes can appear in any order. N is the number of vertices, and the last is automatically connected to the first. Separate polygonal sections are joined by coincident sides. The character coordinate system is a square with lower left corner at (0,0), lower right at (255,0) and upper right at (255,255). @@ -1678,7 +2085,7 @@ The details of this process are not important, but directs the use of a scene description.
The Radiance Software License, Version 1.0
-Copyright (c) 1990 - 2002 The Regents of the University of California,
+Copyright (c) 1990 - 2021 The Regents of the University of California,
through Lawrence Berkeley National Laboratory. All rights reserved.
Redistribution and use in source and binary forms, with or without
@@ -1783,7 +2184,7 @@ are met:
nor may "Radiance" appear in their name, without prior written
permission of Lawrence Berkeley National Laboratory.
-THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+THIS SOFTWARE IS PROVIDED ``AS IS" AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
@@ -1797,6 +2198,8 @@ OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE PO
SUCH DAMAGE.
++