Name
shapefact — obtain shape factors between named regions of mged database
DESCRIPTIONS
shapefact is an interactive program used to create a file containing shape factors between all regions of the named objects. The shape factor from region i to region j is the fraction of total energy radiated from region i that is intercepted by region j. This file can be used with the enhanced engine model developed by Jim Rapp at BRL for use in the PRISM thermal simulation.
Air must be explicitly modeled since shapefact will only calculate shape factors between regions separated by engine air (air code of 5). Shapefact uses a Monte Carlo simulation, so increasing the number of significant digits in the answer by one requires about one hundred fold increase in the number of rays fired.
EXAMPLE
The following is an example from an interactive session.
$ shapefact sph.dsk.g all.air
Enter type of file to be written (0=>regular or 1=>generic). 0
Enter name of output file (15 char max).
sd.sh.reg
Enter the name of the error file (15 char max).
sd.sh.err
Enter the region # & name file to be read (15 char max).
sd.f.rnn
Do you want to dump interm shape factors to screen (0-no, 1-yes)? 0
Enter number of rays to be fired. 5000000
Do you wish to enter your own seed (0) or use the default of 1 (1)? 1
seed initialized
Number of regions read from region # & name file: 4
Database Title: sphere & disk for use with shape
Number of regions: 4
1000000.000000 rays have been fired.
2000000.000000 rays have been fired.
3000000.000000 rays have been fired.
4000000.000000 rays have been fired.
5000000.000000 rays have been fired.
Finding correct region numbers.
Finished finding correct region numbers.
$
CHANGES SINCE BRL-CAD RELEASE 4.0
1. The region number and name file is read so that the numbering of regions is consistent across all irprep programs.
2. A generic output file may now be written.
3. An error file is written.
4. The format of the output file has been changed.
SEE ALSO
firpass(1), secpass(1), all_sf(1), showtherm(1), ir(1), ir-sgi(1), pictx(1), pictsgi(1), User's Manual for IRPREP (BRL-SP-96), Computer Programs for Generating an Input File for PRISM and Displaying PRISM Results (BRL report in progress)
