FIRPASS
1
BRL-CAD
BRL-CAD

# firpass

interrogates an mged file to obtain the facet records of a PRISM-ready input file, a generic thermal data file, or a geometric properties file

      firpass
        model.g
        objects

## DESCRIPTION

Firpass is an interactive program used to create a PRISM ready input file (when used in conjunction with secpass), a generic thermal data file, or a geometric properties file. The following information about each region of the mged description may be obtained from firpass when creating a PRISM ready file.

    	number (arbitrarily assigned by rt_shootray plus one)
    	name (25 right most characters of region name)
    	type (set to 1)
    	exterior surface area (m**2) (surface bounding exterior air)
    	mass (kg)
    	specific heat (J/kg degree C)
    	emissivity
    	surface normal unit vector (averaged over free surface of region)
    	convection coefficient (set to 1)
    	region number seen by back surface (set to 0)
    	region number seen by front surface (set to 0)
    	shape factor (set to 0)
    	hub radius (set to 0)
    	bearing friction constant (set to 0)

The variables set to 0 or 1 need to be changed by the user for special cases.

The following information about each region is obtained when creating a generic thermal data file.

    	number (arbitrarily assigned by rt_shootray plus one)
    	name (25 right most characters of region name)
    	volume (m**3)
    	density (kg/m3)
    	thermal conductivity
    	specific heat
    	material
    	number of external convection surfaces and areas (m**2)
    	number of internal convection surfaces and areas (m**2)
    	number of solar loaded surfaces and areas (m**2)
    	external surface area
    	surface normal unit vector (averaged over free surface of region)
    	absorptivity

The following information about each region is obtained when creating a geometric properties file.

    	number (arbitrarily assigned by rt_shootray plus one)
    	name (25 right most characters of region name)
    	centroid
    	volume (m**3)
    	mass (kg)
    	external surface area (m**2)
    	engine surface area (m**2)
    	crew surface area (m**2)
    	closed compartment surface area (m**2)
    	material code
    	density (kg/m3)
    	specific heat
    	absorptivity
    	emissivity
    	thermal conductivity (W/mK)
    	material
    	all adjacent regions (up to 20)

## EXAMPLE

The following is an example from an interactive session.

    $ firpass test.veh.g vehicle air
    Write output to standard out (0) or a file (1) or not at all (2)?  2
    Enter name of error file to be created (15 char max).  veh.f.err
    Enter name of second pass file to be created (15 char max).  veh.f.2nd
    Enter name of region # & name file to be created (15 char max).  veh.f.rnn
    Enter name of material id file to be read (15 char max).  prp
    Enter type of file to be written.
    	0 - PRISM file
    	1 - Generic file
    	2 - Geometric properties file
    0
    Enter name of facet file to be created. (15 char max)  veh.f.fac
    Which release of PRISM is being used, 2.0 (2) or 3.0 (3)?  3
    Should there be 3 sets of orthogonal rays fired (0) or 1 set
    of rays fired (1)?
    	0
    3 sets of orthogonal rays will be fired.
    File Used:  test.veh.g
    Material ID File:  prp
    Database Title:  test vehicle for use with irprep programs
    Mallocing arrays.
    Zeroing variables.
    Center of bounding rpp ( 356.500000, 0.000000, 1250.000000 )
    Length of diagonal of bounding rpp:  3829.051456
    Minimums & maximums
      x:  -3472.551456 - 4185.551456
      y:  -3829.051456 - 3829.051456
      z:  -2579.051456 - 5079.051456
    Model minimum & maximum.
    	X:  -3001.000000 to 3714.000000
    	Y:  -1350.000000 to 1350.000000
    	Z:  0.000000 to 2500.000000

    Enter grid spacing (mm) for fired rays.
    10

    SHOOTING DOWN THE 1st AXIS

    SHOOTING DOWN THE 2nd AXIS

    SHOOTING DOWN THE 3rd AXIS.
    There are no exterior surfaces on region 19.  Setting exterior surface area
    	to total surface area 31.014883
    There are no exterior surfaces on region 20.  Setting exterior surface area
    	to total surface area 12.235728
    There are no exterior surfaces on region 21.  Setting exterior surface area
    	to total surface area 10.856470

    SUMMARY OF FILES USED & CREATED
    	.g file used:  test.veh.g
    	regions used:
    		vehicle
    		air
    	material id file used:  prp
    	second pass file created:  veh.f.2nd
    	error file created:  veh.f.err
    	region # & name file created:  veh.f.rnn
    	facet file created:  veh.f.fac
    	  (format is PRISM 3.0)

    Freeing memory.

## CHANGES SINCE BRL-CAD RELEASE 4.0

1. Region number and name file is created for use with shapefact and showtherm.

2. The region number is the same across all irprep files, i.e. region numbers start at one not zero. This affects the diagnostic file, the second pass file, and the error file.

3. When there is engine air area it is printed in the radius field of the PRISM facet file.

4. The user is given a choice of a PRISM format of PRISM 2.0 or PRISM 3.0 for the facet file.

5. Addition air types have been added: closed compartment air, exhaust air, generic air 1, and generic air 2.

6. An additional line was added to the end of the PRISM facet file to indicate the end of the file. This line is required by PRISM.

7. If the exterior surface area is zero the total surface area is written out in the exterior surface area field in the PRISM facet file. PRISM will not accept zero in this field.

8. The user is given a choice of firing one set of rays or three sets of orthogonal rays.

## SEE ALSO

secpass 1, shapefact 1, all_sf 1, showtherm 1, ir-X(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)

## AUTHOR

Susan A. Coates

## COPYRIGHT

This software is Copyright (c) 1991-2013 by the United States Government as represented by U.S. Army Research Laboratory.

## BUG REPORTS

Reports of bugs or problems should be submitted via electronic mail to <devs@brlcad.org>.