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ANIM_FLY(nged)		     BRL-CAD User Commands		ANIM_FLY(nged)

       anim_fly	- make animation table to simulate flying motion

       anim_fly	[-f factor] [-r] [-p integer] [-b max_bank_angle] [-s step]
		in.table out.table

       This filter is designed to simulate the motion of an airplane. Given a
       four-column table specifying the	desired	3D position of the airplane at
       each relevant time step,	anim_fly produces a seven-column file which
       also includes the orientation of	the plane in terms of yaw, pitch, and
       roll. The yaw and pitch are manipulated so that the plane faces the
       direction of motion, while the roll is used to do banking.

	   This	option specifies a factor to control the severity of the
	   banking. The	best factor is a subjective decision; a	good starting
	   point can best be obtained by using the
	    -b option. Animations representing aircraft	of different scales
	   will	need different factors.	If the slightest curve throws the
	   plane into a	90-degree bank,	the factor is too large; if it doesn't
	   bank	enough,	the factor is too small. The size of the best factor
	   varies inversely with the size of the imagined aircraft plane. If a
	   factor of 0 is used,	there will be no banking. This would be
	   appropriate for animating a ground vehicle.

	   This	option is used to estimate a good value	for the	-f option. The
	   parameter is	the maximum desired banking angle.  Anim_fly then
	   computes the	factor necessary to keep the banking below the
	   specified angle. This value is returned instead of anim_fly's usual

	   Suppress vertical loop smoothing. A special case occurs if the
	   aircraft is to perform a vertical loop. Normally, the algorithm
	   likes to keep the aircraft right-side up. This would	cause the
	   airplane to do an instantaneous 180-degree roll as it hits the
	   vertical portion of the loop. To counter this, a capability was
	   built in which prevents this	sudden roll, allowing the aircraft to
	   go upside-down in a loop situation. This feature can	be suppressed
	   with	the -r flag.

	   Specify the ratio of	input rows to output rows, which must be an
	   integer. The	default, of course, is one. The	accuracy of the	output
	   depends on having a large number of input lines, which is not
	   usually a problem in	animations, which require a large number of
	   frames per second, anyway. If a test	animation with a small number
	   of frames per second	is being created, the user should still	use an
	   input table with a high number of input rows, reducing the
	   frequency of	the output with	the -p option. For example, if
	   in.table contains 30	rows for each second of	the animation, then
	   the command:

	   anim_fly -f0.001 -p10 < in.table > out.table

	   would produce an animation table containing 3 rows for each second
	   of the animation.

	   Specify the minimum step size for the discrete-time
	   differentiation. At any given point on the flight path, the yaw,
	   pitch, and roll are calculated based	on a past point, the current
	   point, and a	future point. Normally,	these are consecutive points
	   from	the input table. If the	time difference	between	the points
	   falls below a certain threshold, then non-consecutive points	are
	   used	to avoid numerical instability.	The default time threshold is
	   0.1 seconds;	this can be raised or lowered using the	-s option. Try
	   raising the threshold if the	output orientations experience random

       Carl J. Nuzman

       This software is	Copyright (c) 1993-2013	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			ANIM_FLY(nged)


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