| 1 |
|
.\" RCSid "$Id$" |
| 2 |
< |
.TH RPIECE 1 5/25/05 RADIANCE |
| 2 |
> |
.TH RTCONTRIB 1 5/25/05 RADIANCE |
| 3 |
|
.SH NAME |
| 4 |
|
rtcontrib - compute contributions in a RADIANCE scene |
| 5 |
|
.SH SYNOPSIS |
| 26 |
|
rtrace options |
| 27 |
|
] |
| 28 |
|
.B octree |
| 29 |
+ |
.br |
| 30 |
+ |
.B "rtcontrib [ options ] \-defaults" |
| 31 |
|
.SH DESCRIPTION |
| 32 |
|
.I Rtcontrib |
| 33 |
|
computes ray contributions (i.e., color coefficients) |
| 37 |
|
These modifiers are usually materials associated with |
| 38 |
|
light sources or sky domes, and must directly modify some geometric |
| 39 |
|
primitives to be considered in the output. |
| 40 |
< |
The computed contributions can then be used in linear combination to |
| 40 |
> |
The output of |
| 41 |
> |
.I rtcontrib |
| 42 |
> |
has many potential uses. |
| 43 |
> |
Source contributions can be used as components in linear combination to |
| 44 |
|
reproduce any desired variation, e.g., simulating lighting controls or |
| 45 |
|
changing sky conditions via daylight coefficients. |
| 46 |
|
More generally, |
| 47 |
|
.I rtcontrib |
| 48 |
< |
may be used to compute input-output relationships in optical |
| 49 |
< |
systems, such as light pipes and shading devices. |
| 48 |
> |
can be used to compute arbitrary input-output relationships in optical |
| 49 |
> |
systems, such as luminaires, light pipes, and shading devices. |
| 50 |
|
.PP |
| 51 |
|
.I Rtcontrib |
| 52 |
|
calls |
| 63 |
|
a "bin number" within each object if finer resolution is needed, and |
| 64 |
|
this will be applied to a "%d" format in the output file |
| 65 |
|
specification if present. |
| 66 |
< |
(The actual bin number is computed at run time based on ray direction |
| 67 |
< |
and surface intersection, as described below.)\0 |
| 66 |
> |
The actual bin number is computed at run time based on ray direction |
| 67 |
> |
and surface intersection, as described below. |
| 68 |
|
The most recent |
| 69 |
|
.I \-b |
| 70 |
|
and |
| 85 |
|
will be assigned to Dx, Dy, and Dz. |
| 86 |
|
These parameters may be combined with definitions given in |
| 87 |
|
.I \-e |
| 88 |
< |
options and files read in |
| 88 |
> |
arguments and files read using the |
| 89 |
|
.I \-f |
| 90 |
< |
options, to compute the bin, which will be |
| 90 |
> |
option. |
| 91 |
> |
The computed bin value will be |
| 92 |
|
rounded to the nearest whole number. |
| 93 |
|
This mechanism allows the user to define precise regions or directions |
| 94 |
|
they wish to accumulate, such as the Tregenza sky discretization, |
| 95 |
|
which would be otherwise impossible to specify |
| 96 |
|
as a set of RADIANCE primitives. |
| 97 |
+ |
The rules and predefined functions available for these expressions are |
| 98 |
+ |
described in the |
| 99 |
+ |
.I rcalc(1) |
| 100 |
+ |
man page. |
| 101 |
|
.PP |
| 102 |
|
If no |
| 103 |
|
.I \-o |
