TIPSY(1)                  TIPSY COMMANDS                 TIPSY(1)

NAME

       tipsy - theoretical image processing system

SYNOPSIS

       tipsy [-nodisplay] [-address title] [X options]

DESCRIPTION

       The  developement  of  TIPSY  was motivated by the need to
       quickly display and analyze the results of N-body  simula-
       tions.   Most data visualization packages are designed for
       the display of gridded data, and hence are unsuitable  for
       use  with particle data.  Therefore, a special package was
       built that could easily perform the following functions:

       * Display particle positions (as points),  and  velocities
       (as line segments) from an arbitrary viewpoint.

       *  Zoom  in  to a chosen position.  Due to their extremely
       clustered nature, structure of interest in an N-body simu-
       lation  is  often  so  small  that it can not be seen when
       looking at the simulation as a whole.

       * Color particles to display scalar fields.   Examples  of
       such  fields  are  potential energy, or for SPH particles,
       density and temperature.

       * Selection of a subset of the particles for  display  and
       analysis.  Regions of interest are generally small subsets
       of the simulation.

       *  Following  selected  particles  from  one  timestep  to
       another.

       *  Finding cumulative properties of a collection of parti-
       cles.   This usually involves just a sum over  the  parti-
       cles.

       The  basic  data  structure is an array of particle struc-
       tures.  Since TIPSY was built for use with cosmological N-
       body simulations, there are actually three separate arrays
       for each of the types of particle  used  in  such  simula-
       tions:  collisionless  particles,  SPH particles, and star
       particles.  A single timestep is read  into  these  arrays
       from  a disk file.  Display is done by finding the x and y
       coordinates of the particles  in  the  rotated  coordinate
       system,  and  storing  them in arrays.  Screen coordinates
       are calculated from these arrays according to the  current
       zoom  factor.   Also, a software Z-buffer is maintained to
       save time if many particles project  to  the  same  screen
       pixel.

       There  are several types of display.  An ``all plot'' dis-
       plays all particles colored according to  their  type.   A
       ``radial plot'' will color particles according to the pro-
       jection of the velocity along the line-of-sight.  A  ``gas
       plot''  will color gas according to SPH quantities such as
       density, temperature, neutral hydrogen fraction, etc.

       Subsets of particles are maintained  using  ``boxes''.   A
       box  structure  contains  a  bounding box, and an array of
       pointers to particles within the  box.   All  display  and
       analysis  functions  are  performed on the ``active box''.
       By default all particles are  loaded  into  box  0,  which
       becomes the active box.

       If  a  new  timestep  is  read  from  disk,  all boxes are
       destroyed.  A  selection  of  particles  can  be  followed
       between  timesteps via a ``mark'' array.  Marked particles
       are displayed in a different color, and the analysis func-
       tions can be told to only operate on the marked particles.

       To quickly test out tipsy, try the commands:

       openascii run99.ascii

       readascii run99.bin

       loadb 14

       xall




Katz and Quinn Release 2.022 MARCH 1994                  TIPSY(1)