partiview.sgml

<tag>
detach [full|hide]  [<it/+XPOS+YPOS/]
</tag>
Detach graphics window from GUI control strip and optionally
specify position of control strip.  With <tt/full/ or <tt/hide/,
makes graphics window full-screen with GUI visible or hidden, respectively.
With neither <tt/full/ nor <tt/hide/, the graphics window
is detached but left at its current size.

The <it/+XPOS+YPOS/ is a window position in X window geometry style,
so e.g. <tt/detach full -10+5/ places the GUI near the
upper right corner of the screen, 10 pixels in from the right
and 5 pixels down from the top edge.

If you don't mind typing blindly, it's still possible to enter
text-box commands even with the controls hidden;
press the <it>Tab</it> key before each command to ensure that
input focus is in the text box.
Use <it>Tab</it><tt/detach full/<it>Enter</it>
to un-hide a hidden control strip.

<tag>
bgcolor <it/R G B/
</tag>
Set window background color (three R G B numbers or one grayscale value).


<tag>
focallen <it/distance/
</tag>
Focal length: distance from viewer to a typical object of interest.
This affects stereo display (see below) and navigation: the speed of
motion in <tt/[t]ranslate/ and <tt/[f]ly/ modes is proportional to this
distance.

<tag>
stereo [on|off|redcyan|glasses|cross|left|right] [<it/separation/]
</tag>
Stereo display.  Also toggled on/off by typing <tt/'s'/ key in graphics window.
Where hardware allows it, <tt/stereo glasses/ selects
CrystalEyes-style quad-buffered stereo.  All systems should be capable of
<tt/stereo redcyan/, which requires wearing red/green or red/blue glasses,
and of <tt/cross/ (crosseyed), which splits the window horizontally.
<tt/left/ and <tt/right/ show just that eye's view,
and may be handy for taking stereo snapshots.

Useful <it/separation/ values might be 0.02 to 0.1, or -0.02 to -0.1 to swap
eyes.  See also <tt/focallen/ command, which gives the distance to
a typical object of interest: left- and right-eye images of an object
at that distance will coincide on the screen.

Virtual-world eyes will be separated by distance
2 * <it/focallen * separation/, with convergence angle
2 * <tt/arctan(/<it/separation/<tt/)/.

See also the <tt/winsize/ and <tt/detach/ commands
for control over graphics window size and placement.

Beware: some systems which support hardware ("glasses")
stereo also require that the display be set to a
stereo-capable video mode.  Partiview does not do this
automatically.  For example, on stereo-capable SGI Irix systems,
you may need to type (to a unix shell)
<tt>/usr/gfx/setmon -n 1024x768_96s</tt> to allow
stereo viewing and something like <tt>/usr/gfx/setmon -n 72</tt>
to revert.  Otherwise, turning partiview's stereo on
will just show the left eye's view -- displacing the viewpoint
but nothing else.

<tag>
snapset [<tt/-n/ <it/FRAMENO/] <it/FILESTEM/ [<it/FRAMENO/]
</tag>
Set parameters for future <tt/snapshot/ commands.
<it/FILESTEM/ may be a printf format string with frame number as
argument, e.g. <tt>snapset pix/%04d.ppm</tt>, generating image names
of <tt>pix/0000.ppm</tt>, <tt>pix/0001.ppm</tt>, etc.
If <it/FILESTEM/ contains no % sign, then <tt/.%03d.ppm.gz/ is
appended to it, so <tt>snapset ./pix/fred</tt>
yields snapshot images named <tt>./pix/fred.000.ppm.gz</tt> etc.
<p>
Frame number <it/FRAMENO/ (default 0) increments with each snapshot taken.
<p>

<tag>
snapshot [<it/FRAMENO/ | <it/FILENAME/]
</tag>
Capture a snapshot image of the current view.

Either give <tt/snapshot/ an explicit filename,
or else specify a file format string with <tt/snapset/
and then let <tt/snapshot/ fill in the frame number.
With neither <it/FRAMENO/ nor <it/FILENAME/,
<tt/snapset/ adds one to the previous frame number.

<tt/Partiview/ generally invokes the ImageMagick program <tt/convert(1)/,
which must be installed and be on the user's $PATH.  <tt/Convert/ determines
the type of image (jpeg, sgi, bmp, etc.) based on the file suffix.

<tt/Convert/ is not needed if the <tt/snapset/ <it/FILESTEM/ ends in
<tt/.ppm.gz/ (invokes gzip rather than convert) or <tt/.ppm/
(no external program required).

</descrip>


<sect1>Particle Display Control Commands
<p>
These commands affect how particles (in the current group) are
displayed.

<descrip>
<tag>
psize <it/scalefactor/
</tag>
All particle luminosities (as specified by <tt/lum/ command)
are scaled by the product of two factors:
a <it/lumvar/-specific factor given by <tt/slum/,
and a global factor given by <tt/psize/.
So the intrinsic brightness of a particle is
<it/value-specified-by-/<tt/lum/
* <it/slum-for-current-lumvar/
* <it/psize-scalefactor/.

<tag>
slum <it/slumfactor/
</tag>
Data-field specific luminosity scale factor, for current choice of
<it/lumvar/ as given by the <tt/lum/ command.
A <it/slumfactor/ is recorded independently for each data field, so
if data fields <tt/mass/ and <tt/energy/ were defined, one might say
<tscreen><verb>
lum mass
slum 1000
lum energy
slum 0.25
</verb></tscreen>
having chosen each variable's <it/slumfactor/ for useful display,
and then freely switch between <tt/lum mass/ and <tt/lum energy/
without having to readjust particle brightness each time.

<!--  Just describe "slum"
<tag>
scale-lum
</tag>
 -->

<tag>
ptsize <it/minpixels/ <it/maxpixels/
</tag>
Specifies the range of <it/apparent/ sizes of points,
in pixels.  Typical values might be <tt/ptsize 0.1 5/.
The graphics system may silently impose an upper limit
of about 10 pixels.

<!-- DEPRECATED COMMAND
<tag>
pointsize 
</tag>
-->

<tag>
poly [on|off]
</tag>
Display polygons, or don't.


<tag>
polysize [<it/scalefactor/]
</tag>
Multiplier for polygon size.  Default is zero (!), so you must
set polysize to something else before polygons will show up.

<tag>
polylumvar [<it/attrname/ | <tt/point-size/] [<tt/area/ | <tt/radius/]
</tag>
Choose which attribute determines the radius of a particle's polygon.
By default, it is <tt/point-size/, a pseudo-attribute which varies with
the brightness of points (so adjusting the slum slider scales polygons too).

Each polygon's 3-D radius is the <tt/polysize/ <it/scalefactor/ times its particle's
given attribute (whether an actual particle attribute or <tt/point-size/).  Or,  
if the <tt/area/ keyword is specified, then the radius is the square root
of attribute * scalefactor.   <tt/area/ is useful if the attribute represents
a luminosity; in that case, the polygon total brightness (which is proportional
to its screen area) becomes proportional to the attribute / distance^2.

<tag>
polymin <it/minradius/ [<it/maxradius/]
</tag>
Specify a minimum screen radius for polygons, in pixels.
If smaller than this, they are not drawn.

<tag>
color
</tag>
   Specify how particles are colored.
   Generally, a linear function of some data field of each particle
   becomes an index into a colormap (see <tt/cmap/, <tt/cment/).
    <descrip>
    <tag> color  <it/colorvar/  [<it/minval maxval/] </tag>
	Use data field <it/colorvar/ (either a name as set by <tt/datavar/
	or a 0-based integer column number) to determine color.
	Map <it/minval/ to color index 1, and <it/maxval/ to
	the next-to-last entry in the colormap (<it/Ncmap-2/).
	The 0th and last (<it/Ncmap-1/) colormap entry are used for
	out-of-range data values.

	If <it/minval/ and <it/maxval/ are omitted, the actual range of
	values is used.
	
    <tag> color  <it/colorvar/  exact  [<it/baseval/] </tag>
	Don't consider field <it/colorvar/ as a continuous variable;
	instead, it's integer-valued, and mapped one-to-one with
	color table slots.  Data value <it/N/ is mapped to
	color index <it/N+baseval/.

    <tag> color  <it/colorvar/  -exact </tag>
	Once the <tt/exact/ tag is set (for a particular data-field),
	it's sticky.  To interpret that data field as a continuous, scalable
	variable again, use <tt/-exact/.
	
    <tag> color  const  <it/R G B/ </tag>
	Show all particles as color <it/R G B/, each value in range 0 to 1,
	independent of any data fields.
    </descrip>

<tag>
lum
</tag>
   Specify how particles' intrinsic luminosity is computed:
   a linear function of some data field of each particle.
   <descrip>
   <tag> lum <it/lumvar/  [<it/minval maxval/] </tag>
	Map values of data field <it/lumvar/ (<tt/datavar/ name or
	field number) to luminosity.
	The (linear) mapping takes field value <it/minval/ to
	luminosity 0 and <it/maxval/ to luminosity 1.0.
	<p>
	If <it/minval/ and <it/maxval/ are omitted,
	the actual range of values is mapped to the luminosity range
	0 to 1.
	<p>
	Note that the resulting luminosities are then scaled by
	the <tt/psize/ and <tt/slum/ scale factors, and further
	scaled according to distance as specified by <tt/fade/, to compute
	apparent brightness of points.

   <tag> lum const <it/L/ </tag>
	Specify constant particle luminosity <it/L/ independent of
	any data field values.
   </descrip>

<tag>
fade [planar|spherical|linear <it/refdist/|const <it/refdist/]
</tag>
Determines how distance affects particles' apparent brightness (or "size").
The default <tt/fade planar/ gives 1/r^2 light falloff, with r measured
as distance from the view plane.  <tt/fade spherical/ is also 1/r^2,
but with r measured as true distance from the viewpoint.
<tt/fade linear/ <it/refdist/ gives 1/r light falloff -- not physically
accurate, but useful to get a limited sense of depth.
<tt/fade const/ <it/refdist/ gives constant apparent brightness
independent of distance, and may be appropriate for orthographic views.

The <it/refdist/ for linear and const modes is that distance <it/r/
at which apparent brightness should match that in the 1/r^2 modes --
a distance to a "typical" particle.

<tag>
labelmin  <it/minpixels/
</tag>
Labels computed to be smaller than this screen size (pixels) are suppressed.

<tag>
labelsize <it/scalefactor/
</tag>

<tag>
lsize <it/scalefactor/
</tag>
lsize (alias labelsize) sets the 3-D height of labels.  If the text was created with a
<tt/text -size /<it/textsize/ option, the scalefactor is multiplied by that to determine
the 3-D size.

<tag>
point[s]   [on|off]
</tag>
Turn display of points on or off.  With no argument, toggles display.

<tag>
poly[gons]  [on|off]
</tag>
Turn display of points on or off.  With no argument, toggles display.

<tag>
texture [on|off]
</tag>
Turn display of textures on or off.  With no argument, toggles.

<tag>
label[s] [on|off]
</tag>
Turn display of label text on or off.  With no argument, toggles.


<tag>
txscale	 <it/scalefactor/
</tag>
Scale size of all textures relative to their polygons.
A scale factor of 0.5 (default) make the texture square
just fill its polygon, if <tt/polysides/ is 4.

<tag>
polyorivar
</tag>
Report setting of <tt/polyorivar/ data-command, which see.

<tag>
texturevar
</tag>
Report setting of <tt/texturevar/ data-command, which see.

<tag>
laxes  [on|off]
</tag>
Toggle label axes.  When on, and when labels are displayed,
shows a set of red/green/blue (X/Y/Z) axes to indicate orientation.

<tag>
polyside(s)
</tag>
Number of sides a polygon should have.  Default 11, for fairly round
polygons.  For textured polygons, <tt/polysides 4/ might do as well,
and be slightly speedier.

<tag>
fast [on|off]
</tag>
see also <tt/ptsize/

<tag>
ptsize  <it/minpixels/ [<it/maxpixels/]
</tag>
Specifies range of apparent (pixel) size of points.
Those with computed sizes (based on luminosity
and distance) smaller than <it/minpixels/ are
randomly (but repeatably) subsampled -- i.e. some
fraction of them are not drawn.  Those computed to be
larger than <it/maxpixels/ are drawn at size
<it/maxpixels/.

<tag>
gamma <it/displaygamma/
</tag>
Tells the particle renderer how the display + OpenGL
relates image values to visible lightness.
You don't need to change this, but may adjust it
to minimize the brightness glitches when particles change size.
Typical values are <tt/gamma 1/ through <tt/gamma 2.5/ or so.
Larger values raise the apparent brightness of dim things.

<tag>
alpha <it/alpha/
</tag>
Get or set the alpha value, in the range 0 to 1; it determines
the opacity of polygons.

<tag>
speed
</tag>
For time-dependent data, advance datatime by this many time units
per wall-clock second.

<tag>
step [<it/timestep/]
</tag>
For time-varying data, sets current timestep number.
Real-valued times are meaningful for some kinds of data including those
from Starlab/kira; for others, times are rounded to nearest integer.
If running, <tt/step/ also stops datatime animation.  (See <tt/run/.)

<tag>
step [+|-]<it/deltatimestep/
</tag>
If preceded with a plus or minus sign, adds that amount to current time.


(note that <tt/fspeed/ has been deprecated)

<tag>
run
</tag>
Continue a stopped animation (see also <tt/step/).

<tag>
tfm [-v] [<it/numbers.../]
</tag>
Object-to-world transformation. 
May take 1, 6, 7, 9 or 16 parameters: either 
<it/scalefactor/,
or <it/tx ty tz rx ry rz /<it/scalefactor/>],
or 16 numbers for 4x4 matrix,
or 9 numbers for 3x3 matrix.
See <it/Coordinates and Coordinate Transformations/.

With no numeric parameters, reports the current object-to-world transform.
Use <tt/tfm -v/ to see the transform and its inverse in several forms.

<tag>
move [g<it/N/] {on|off}
</tag>
Normally, navigation modes <tt/[r]otate/ and <tt/[t]ranslate/
just adjust the viewpoint (camera).  However,
if you turn <tt/move on/, then <tt/[r]otate/ and <tt/[t]ranslate/
move the currently-selected object group instead,
e.g. to adjust its alignment relative to other groups.
(<tt/[o]rbit/ and <tt/[f]ly/ modes always move the camera.)

To indicate that <tt/move/ mode is enabled,
the control strip shows the selected group's name in
bold italics, as <bf><it>[g3]</it></bf>.
Use <tt/move off/ to revert to normal.
The <tt/tfm/ command reports the current object-group-to-global-world
transformation.

<tag>
fwd
</tag>

<tag>
datawait   on|off
</tag>
For asynchronously-loaded data (currently only <tt/ieee/ data command),
say whether wait for current data step to be loaded.
(If not, then keep displaying previous data while loading new.)

<tag>
cmap    <it/filename/
</tag>
Load (ascii) filename with RGB values, for coloring particles.
The <tt/color/ command selects which data field is mapped to color index
and how.

Colormaps are text files, beginning with a number-of-entries
line and followed by R G B or R G B A entries one per line;
see the <it/Colormaps/ section.

<tag>
vcmap -v <it/fieldname/  <it/filename/
</tag>
Load colormap as with <tt/cmap/ command.  But use this colormap
only when the given data field is selected for coloring.
Thus the <tt/cmap/ color map applies to all data fields for which
no <tt/vcmap/ has ever been specified.

<tag>
cment  <it/colorindex/  [<it/R G B/]
</tag>
Report or set that colormap entry.

<tag>
rawdump <it/dump-filename/
</tag>
All particle attributes (not positions though) 
are written to a <it/dump-filename/.  Useful for debugging.
Warning: it will happily overwrite an existing file with that name.

<tag>
warp [on|off]
</tag>
Enable, disable, or report the status of any <tt/warp/ data-command set up for the current group.
If it exists, particles's positions can change with time, in a handful of canned ways
built into the <tt/warp/ command.  See the <tt/warp/ entry under Data Commands.

</descrip>

<sect1>Particle subsetting & statistics
<p>

<descrip>

<tag>
clipbox ...
</tag>
see <tt/cb/ below.

<tag>
cb ....
</tag>
Display only a 3D subregion of the data -- the part lying within the clipbox.
    <descrip>
    <tag>cb <it/xmin ymin zmin  xmax ymax zmax/ </tag> <p>
	Specified by coordinate ranges.
        Note only spaces are used to separate the 6 numbers.
    <tag>cb <it/xcen,ycen,zcen xrad,yrad,zrad/  </tag>
	Specified by center and "radius" of the box.
	Note no spaces after the commas!
    <tag>cb <it/xmin,xmax ymin,ymax zmin,zmax/  </tag>
        Specified by coordinate ranges.
    <tag>cb <tt/off/ </tag><p>
	Disable clipping.  The entire dataset is again visible.
    <tag>cb <tt/on/  </tag><p>
	Re-enable a previously defined clipbox setting. It will also
        display the clipbox again
    <tag>cb <tt/hide/  </tag><p>
        Hide the clipbox, but still discard objects whose centers
	lie outside it.
    </descrip>
Note this command does not toggle clipping
if no arguments given (that would be handy
and more in line with similar commands). 
If no arguments given, it reports the current clipbox.

<tag>
thresh
</tag>
   Display a subset of particles, chosen by the value of
   some data field.  Each <tt/thresh/ command overrides
   settings from previous commands, so it cannot be used to
   show unions or intersections of multiple criteria.
   For that, see the <tt/only/ command.  However, unlike <tt/only/,
   the <tt/thresh/ criterion applies to time-varying data.
   <descrip>
   <tag>thresh <it/field/ <it/minval/ <it/maxval/ </tag>
	Display only those particles where
	<it/minval/ &lt;= field <it/field/ &lt;= <it/maxval/.
	The <it/field/ may be given by name (as from <tt/datavar/)
	or by field number.
   <tag>thresh <it/field/ <tt/&lt;/<it/maxval/ </tag> <p>
   <tag>thresh <it/field/ <tt/&gt;/<it/minval/ </tag>
	Show only particles where <it/field/ is &lt;=
	or &gt;= the given threshold.
   <tag>thresh [off|on]</tag>
	Disable or re-enable a previously specified threshold.
   </descrip>

<tag>
only=  <it/datafield/  <it/value/  <it/minvalue-maxvalue/  &lt;<it/value/ &gt;<it/value/ ...
</tag>
<tag>
only+  <it/datafield/  <it/value/  <it/minvalue-maxvalue/  &lt;<it/value/ &gt;<it/value/ ...
</tag>
<tag>
only-  <it/datafield/  <it/value/  <it/minvalue-maxvalue/  &lt;<it/value/ &gt;<it/value/ ...
</tag>
Scans particles (in the current timestep only!), finding those where
<it/datafield/ has value <it/value/, or has a value in range
<it/minvalue/ &lt;= value &lt;= <it/maxvalue/, or whatever.
Multiple value-ranges may be specified to select the union of several sets.
The resulting set of particles is assigned to (<tt/only=/), added to
(<tt/only+/) or subtracted from (<tt/only-/) the <tt/thresh/ selection-set.
Also display just particles in that selection-set, as if <tt/see thresh/
had been typed.

The net effect is illustrated by these examples:
<descrip>
  <tag>only= type 1-3 5</tag>
	Show only particles of type 1, 2, 3 or 5.
  <tag>only- mass &lt;2.3  &gt;3.5</tag>
	After the above command, shows only the subset
	of type 1/2/3/5 particles AND have mass between 2.3 and 3.5.
	(Note that to take the intersection of two conditions,
	you must subtract the complement of the latter one.
	Maybe some day there'll be an <tt/only&amp;/.
</descrip>

<tag>
see  <tt/selexpr/
</tag>
Show just those particles in the selection-set <tt/selexpr/.
Predefined set names are <tt/all/, <tt/none/, <tt/thresh/ and <tt/pick/,
and other names may be defined by the <tt/sel/ command.
The default is <tt/see all/.  Using the <tt/thresh/ or <tt/only/
commands automatically switch to displaying <tt/see thresh/.

Note that you can see the complement of a named set,
e.g. all except the <tt/thresh/-selected objects, with
<tt/see -thresh/.

<tag>
sel <tt/selname = selexpr/
</tag>
Compute a logical combination of selection-sets and assign them
to another such set.  The set membership is originally assigned by
<tt/thresh/ or <tt/only/ commands.  Yeah, I know this doesn't make sense.
Need a separate section to document selection-sets.

<tag>
sel <tt/selexpr/
</tag>
Count the number of particles in the selection-set <tt/selexpr/.

<tag>
clearobj
</tag>
Erase all particles in this group.  Useful for reloading on the fly.

<tag>
every   <it/N/
</tag>
Display a random subset (every <it/N/-th) of all particles.
E.g. <tt/every 1/ shows all particles, <tt/every 2/ shows about half of them.
Reports current subsampling factor, and the current total number of particles.

<tag>
hist <it/datafield/ [-n <it/nbuckets/] [-l] [-c] [-t] [<it/minval/] [<it/maxval/]
</tag>
Generates a (numerical) histogram of values of <it/datafield/,
which may be a named field (as from <tt/datavar/) or a field index.
Divides the value range (either <it/minval/..<it/maxval/
or the actual range of values for that field) into <it/nbuckets/ 
equal buckets (11 by default).  Uses logarithmically-spaced
intervals if <tt/-l/ (so long as the data range doesn't include zero).
If a clipbox is defined, use <tt/-c/ to count only
particles within it.  If a <tt/thresh/ or <tt/only/
subset is defined, use <tt/-t/ to count only the chosen subset.

<tag>
bound  [w]
</tag>
Reports 3D extent of the data.  With <tt/w/, reports it in
world coordinates, otherwise in object coordinates.

<tag>
datavar
</tag>

<tag>
dv
</tag>
Report names and value ranges (over all particles in current group)
of all named data fields.


</descrip>

<sect1>Boxes
<p>
<descrip>
<tag>
showbox  <it/list of integer box level numbers.../
</tag>

<tag>
hidebox  <it/list of integer box level numbers.../
</tag>

<tag>
box[es] [off|on|only]
</tag>
Turn box display off or on; or display boxes but hide all particles.

<tag>
boxcmap <it/filename/
</tag>
Color boxes using that colormap.
Each box's level number (set by <tt/-l/ option of <tt/box/ data-command,
default 0) is the color index.

<tag>
boxcment  <it/colorindex/  [<it/R G B/]
</tag>
Get or set the given box-colormap index.  E.g. <tt/boxcment 0/
reports the color of boxes created with no <tt/-l/ specified.

<tag>
boxlabel [on|off]
</tag>
Label boxes by id number
(set by <tt/-n/ option of <tt/box/ data-command).

<tag>
boxaxes [on|off]
</tag>
Toggle or set box axes display mode.

<tag>
boxscale [float] [on|off] 
</tag>

<tag>
gobox <it/boxnumber/
</tag>

<tag>
goboxscale
</tag>

<tag>
menu fmenu
</tag>

<p>
<tscreen><verb>

			BEGIN CAVEMENU
	pos P1 P2
	wall P1
	hid [P1]
	show [P1]
	h  [P1]
	demandfps [P1]
	font
	help
	?
			END CAVEMENU	
</verb></tscreen>
<p>

<tag>
datascale
</tag>

</descrip>

<!--------------------------------------------------------------------------- -->
<sect1> <!-- label id="datacommands" --> Data commands </>
<p>

(see also partibrains.c::specks_read)
<p>
Data Commands can be placed in a data file.
Lines starting with <tt/#/ will be skipped. 
<p>
Control Commands can also be given, if prefixed with the <tt/eval/ command.

<descrip>

<tag>
read <it/file/ 
</tag> 
read a <tt/speck/ formatted file. Recursive, commands can nest. (strtok ok??)
Note that <tt/read/ is also a Control Command, doing exactly the same thing.

<tag>
include  <it/file/
</tag>
read a <tt/speck/ formatted file.

<tag>
ieee [-t time] <it/file/
</tag>
Read a IEEEIO formatted file, with optional timestep number (0 based).
Support for this type of data must be explicitly compiled into the program.

<tag>
kira <it/file/ 
</tag> 
read a <tt/kira/ formatted file. See the <tt/kiractl/ Control
Command to modify the looks of the objects.  Only present if Starlab is compiled
into partiview.

<tag>
setenv name value
</tag>
Add (or change) a named variable of the environment variables space of
partiview. Enviroment variables, like in the normal unix shell, can be
referred to by prepending their name with a $. 
<it/Note there probably is not an unsetenv command/.

<tag>
object <it/gN=ALIAS/
</tag>
Defines/Selects a particular group number (N=1,2,3....) to an ALIAS. In
command mode you can use <tt/gN=ALIAS/. Any data following this command
will now belong to this group.

<tag>
object <it/ObjectName/
</tag>
Select an existing group. Following data will now belong to this group.

<tag>
sdbvars <it/var/
</tag>
Choose which data fields to
extract from binary sdb files (any of: <tt/mMcrogtxyzSn/) for subsequent
<tt/sdb/ commands.

<tag>
sdb [-t time] <it/file/
</tag>
Read an SDB (binary) formatted file, with optional timestep number.
(Default time is latest <tt/datatime/, or 0.)

<tag>
pb [-t time] <it/file/
</tag>
Read a <tt/.pb/ (binary) particle file, with optional timestep number.
(Default time is latest <tt/datatime/, or 0.)
A <tt/.pb/ file contains (all values 32-bit integer or 32-bit IEEE float):
<enum>
  <item>magic number, 0xFFFFFF98  (int32)
  <item>byte offset of first particle (int32)
  <item>number of attributes (int32)
  <item>sequence of null-terminated attribute name strings,
	attributename0 \0 attributename1 \0 ...
  <item>possibly some pad bytes, enough to reach the specified
	first-particle file offset
  <item>sequence of particle records,
	each (number-of-attributes + 4)*4 bytes long:
	<enum>
	  <item>particle-id (int32)
	  <item>particle X, Y, Z (3 float32's) 
	  <item>particle attributes (number-of-attributes float32's)
	</enum>
	ending at the end of the file (i.e. there's no particle-count field).
</enum>
Either big- or little-endian formats are accepted; the value of the
magic number determines endianness of all values in that file.

<tag>
box[es] <it/..../
</tag>
Draw a box, using any of the following formats:
<p>
    <descrip>
    <tag> <tt/xmin ymin zmin  xmax ymax zmax/ </tag> <p>
    <tag> <tt/xmin,xmax ymin,ymax zmin,zmax/   </tag><p>
    <tag> <tt/xcen,ycen,zcen xrad,yrad,zrad/  </tag><p>
    <tag> <tt/[-t time] [-n boxno] [-l level] xcen,ycen,zcen  xrad,yrad,zrad /  </tag><p>
    </descrip>
<tt/level/ determines color.

<tag>
<tt/mesh/ [<tt/-t/ <it/txno/] [<tt/-c/ <it/colorindex/] [<tt/-s/ <it/style/]
</tag>
Draw a quadrilateral mesh, optionally colored or textured.
Following the <bf/mesh/ line, provide a line with the mesh dimensions:
<screen>
         nu nv
</screen>

Following this comes the list of <it/nu/*<it/nv/ mesh vertices,
one vertex (specified by several blank-separated numbers) per line.
(Blank lines and comments may be interspersed among them.)
Note that the mesh connections are implicit:
vertex number i*nu+j is adjacent to (i-1)*nu+j, (i+1)*nu+j, i*nu+(j-1),
and i*nu+(j+1).  Each vertex line has three or five numbers:
the first three give its 3-D position, and if a <tt/-t/ texture was
specified, then two more fields give its u and v texture coordinates.
<p>

Options:
  <descrip>
    <tag> <tt/-t/ <it/txno/ </tag> Apply texture number <it/txno/ to surface.
	In this case, each mesh vertex should also include
	u and v texture coordinates.
    <tag> <tt/-c/ <it/colorindex/ </tag> Color surface with color from
	integer cmap entry <it/colorindex/.
    <tag> <tt/-s/ <it/style/ </tag>
	Drawing style: <descrip>
	  <tag> <it/solid/ </tag> filled polygonal surface (default)
	  <tag> <it/wire/ </tag>  just edges
	  <tag> <it/point/ </tag> just points (one per mesh vertex)
	</descrip>
   </descrip>

<tag>
<it/Xcen Ycen Zcen/ ellipsoid <it/[options]... [transformation]/
</tag>
Draw an ellipsoid, specified by:
  <descrip>
  <tag> <tt/Xcen Ycen Zcen/ </tag>  Center position in world coordinates
  <tag> <tt/-c/ <it/colorindex/ </tag> Integer color index (default -1 => white)
  <tag> <tt/-s/ <it/style/ </tag>
	Drawing style: <descrip>
	  <tag> <it/solid/ </tag> filled polygonal surface (default)
	  <tag> <it/plane/ </tag> 3 ellipses: XY, XZ, YZ planes
	  <tag> <it/wire/ </tag> latitude/longitude ellipses
	  <tag> <it/point/ </tag> point cloud: one per lat/lon intersection
	</descrip>
  <tag> <tt/-r/ <it/Xradius/[,<it/Yradius/,<it/Zradius/] </tag>
	Radius (for sphere) or semimajor axes (for ellipsoid)
  <tag> <tt/-n/ <it/nlat[,nlon]/ </tag>
	Number of latitude and longitude divisions.
	Relevant even for <it/plane/ style, where they determine
	how finely the polygonal curves approximate circles.
	Default <it/nlon/ = <it/nlat//2 + 1.
  <tag> <it/transformation/ </tag>
	Sets the spatial orientation of the ellipsoid.
	May take any of three forms:
	<descrip>
	  <tag> (nothing) </tag> If absent, the ellipsoid's
		coordinate axes are the same as the world axes
		for the group it belongs to.
	  <tag> 9 blank-separated numbers </tag>
		A 3x3 transformation matrix T from ellipsoid coordinates
		to world coordinates, in the sense
		Pworld = Pellipsoid * T  +  [Xcen, Ycen, Zcen].
	  <tag> 16 blank-separated numbers </tag>
		A 4x4 transformation matrix, as above but for the
		obvious changes.
	</descrip>
  </descrip>

<tag>
waveobj [-time <it/timestep/] [-static] [-texture <it/number/] [-c <it/colorindex/] [-s <it/style/]  <it/file.obj/
</tag>
Load a Wavefront-style .obj model.  Material properties are
ignored; the surface is drawn in white unless <tt/-c/ <it/colorindex/
in which case it's drawn using that color-table color.
Also if <tt/-texture/ (alias <tt/-tx/) is supplied,
the surface is textured using whatever texture coordinates are
supplied in the .obj file.  The model is displayed at all times
only if marked <tt/-static/; otherwise it's displayed only
at the time given by <tt/-time/ <it/timestep/ or by the most recent <it/datatime/.

A subset of the .obj format is accepted:
<descrip>
  <tag>v <it/X Y Z/</tag> -- vertex position
  <tag>vt <it/U V/</tag> -- vertex texture coordinates
  <tag>vn <it/NX NY NZ/</tag> -- vertex normal
  <tag>f <it/V1 V2 V3 .../</tag> -- face, listing just position indices for each vertex.
	The first <tt/v/ line in the .obj file has index 1, etc.
  <tag>f <it>V1/T1 V2/T2 V3/T3 ...</it></tag> -- face,
	listing position and texture coordinates for each vertex of the face.
  <tag>f <it>V1/T1/N1 V2/T2/N2 V3/T3/N3 ...</it></tag> -- face,
	listing position, texture-coordinate, and normal indices for each vertex.
</descrip>
Note that material properties (mtl) are ignored.  Waveobj models are colored
according to the <tt/-c/ <it/colorindex/ option (integer index
into the current <tt/cmap/ colormap), or white if no <tt/-c/ is used. 
If texturing is enabled -- if the .obj model contains <tt/vt/ entries,
and the <tt/-texture/ option appears, and that numbered texture exists --
then the given texture color multiplies or replaces the <tt/-c/ color,
according to the texture options.


<tag>
tfm [camera] <it/numbers.../
</tag>
Object-to-world transformation.
May take 1, 6, 7, 9 or 16 numbers: either 
<it/scalefactor/ or 
<it/tx ty tz rx ry rz /[it/scalefactor/]
or 16 numbers for 4x4 matrix,
or 9 numbers for 3x3 matrix.
See <it/Coordinates and Coordinate Transformations/.

Normally the transform is to world coordinates;
but with optional <tt/camera/ prefix, the object's position
is specified relative to the camera, useful to place
legends in a fixed position on the screen.
In camera coordinates, (0,0,0) is the viewpoint,
x=y=0 at screen center, and negative z extends forward.
Try for example
<verb>
    tfm camera -3 -3 -20  0 0 0
    0 0 0 text -size 20  Legend
</verb>

<tag>
eval <it/command/
</tag>
execute a Control Command.

<tag>
feed  <it/command/
</tag>
Synonym for <tt/eval/.

<tag>
VIRDIR  <it/command/
</tag>
Synonym for <tt/eval/.

<!-- DEPRECATED COMMAND
<tag>
ignorefirst, ignorepgc
</tag>
-->

<tag>
filepath <it/path/
</tag>
A colon-separated list of directories in which datafiles, color maps, etc.
will be searched for. If preceded with the <tt/+/ symbol,
this list will be appended to the current <it/filepath/.

<tag>
polyorivar <it/indexno/
</tag>
By default, when polygons are drawn, they're parallel to the screen plane --
simple markers for the points.  It's sometimes useful to give each 
polygon a fixed 3-D orientation (as for disk galaxies).  To do this,
provide 6 consecutive data fields, representing two 3-D orthogonal unit
vectors which span the plane of the disk.  Then use
<tt/polyorivar /<it/indexno/
giving the data field number of the first of the 6 fields.
The vectors define the X and Y directions on the disk, respectively --
relevant if texturing is enabled.
<p>
Actually, unit vectors aren't essential; making them different lengths
yields non-circular polygonal disks. 
<p>
If <tt/polyorivar/ is specified for the group, but some polygons should
still lie in the screen plane, use values <tt/9 9 9 9 9 9/ for those polygons.

<tag>