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RT_BOT_FACES(1)			    BRL-CAD		       RT_BOT_FACES(1)

       rt_bot_faces - raytrace a model,	and write a file listing all the BOT
       facets hit first	on any shotline.

       rt_bot_faces [options...] model.g objects...

       Rt_Bot_Faces operates on	the indicated objects in the input model.g and
       fires rays (the same as RT) keeping a list of all the first-hit BOT

       The orientation of the rays to be fired may be specified	by the -a and
       -e options, in which case the model will	be autosized, and the grid
       will be centered	on the centroid	of the model, with ray spacing chosen
       to span the entire set of objects.  Alternatively, with the -M option,
       a transformation	matrix may be provided on standard input which maps
       model-space to view-space. In this case,	the grid ranges	from -1.0 <=
       X,Y <= +1.0 in view space, with the size	of the grid (number of rays
       fired) specified	with -s. This option is	most useful when rt_bot_faces
       is being	invoked	from a shell script created by an mged(1) saveview
       command.	Note that it conflicts with -G#	and -g#; negative hit
       distances have been seen	when this conflict was not avoided.

       The following options are recognized.

	   Number of rays to fire in X and Y directions	(square	grid). Default
	   is 512 (512x512).

	   Select azimuth in degrees. Used with	-e and conflicts with -M.

	   Select elevation in degrees.	Used with -a and conflicts with	-M.

	   Read	model2view matrix from standard	input. Conflicts with -a and

	   Select grid cell width. Do not use with the -s# option.

	   Select grid cell height. If not specified, cell height equals cell
	   width. Do not use with the -s# option.

       -U #
	   sets	the Boolean variable use_air to	the given value. The default
	   for rt_bot_faces(1) is on, i.e.  -U1, but the effect	of air regions
	   may be disabled with	-U0.

       -o output_bot_faces
	   specifies a named file to receive the list of BOT facets that
	   appear as first surface hit on any ray. By default, the data	are
	   written to stdout. The format of the	output is a header line	for
	   each	BOT primitive that appeared as the first object	on any ray of
	   the form:

		    BOT: bot_primitive_name

	   This	is followed by a list of facet numbers for that	BOT primitive
	   (one	per line). The facet numbers are indices into the list of
	   faces (starting from	zero) for that BOT primitive. If the output
	   file	is not empty, it is expected to	contain	data from a previous
	   execution of	rt_bot_faces, and the data in the file is read,	and
	   stored, new data is added to	it during the execution, and the
	   output file is overwritten with the accumulated data.

	   Set librt debug flags to (hexadecimal) number.

       -c set rt_cline_radius=#
	   Tells rt_bot_faces(1) to use	the provided number (in	millimeters)
	   as the additional radius to add to CLINE solids.

       -c set save_overlaps=1
	   Tells rt_bot_faces(1) to act	like the FASTGEN4 raytracer.
	   Specifically, overlap handling is changed to	agree with that	of

       The rt_bot_faces	program	is a simple front-end to librt(3).

       This section will acquaint the user with	the ordinary usage of
       rt_bot_faces. the typical use is:

	   rt_bot_faces	-s32 model.g all.g > file

       This will fire a	square grid of 32 by 32	rays at	the named model	and
       the resulting list of BOT facets	will be	placed in "file".

       RT_BOT_FACES shares overlap handling and	reporting with the rest	of the
       RT family of applications. A brief description of the overlap reporting

       The first one hundred (100) overlaps are	individually reported.
       Thereafter, only	one out	of each	additional one hundred overlaps	are
       reported, and the user is notified that overlap printouts are being
       omitted.	This alerts the	user that more overlaps	exist, but that	they
       are too numerous	to list	individually. The general overlap message
       takes the following form:

	       OVERLAP1: reg=region_name isol=solid_name
	       OVERLAP2: reg=region_name isol=solid_name
	       OVERLAP depth #mm at (x,	y, z) sx# sy# lvl#

       This means that OVERLAP1	and OVERLAP2 share a common space (depth) of
       #millimeters starting at	the point x, y,	z in model coordinates,	and at
       the ray coordinates (screen coordinates)	sx and sy. Level refers	to the
       level of	recursion, and will typically be zero unless glass or mirror
       objects are present.

       mged(1),	rt(1), rtray(1), librt(3), plot3(5), ray(5V).

       Numerous	error conditions are possible, usually due to errors in	the
       geometry	database. Descriptive messages are printed on standard error
       (file descriptor	2).

       BRL-CAD Team

       This software is	Copyright (c) 2003-2013	by the United States
       Government as represented by U.S. Army Research Laboratory.

       Reports of bugs or problems should be submitted via electronic mail to

BRL-CAD				  07/08/2017		       RT_BOT_FACES(1)


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