TIPSY(1) Katz and Quinn Release 2.0 (22 MARCH 1994) 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
simulations. 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 simulation
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
particles. This usually involves just a sum over the particles.
The basic data structure is an array of particle structures.
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 simulations:
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''
displays all particles colored according to their type. A
``radial plot'' will color particles according to the
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TIPSY(1) Katz and Quinn Release 2.0 (22 MARCH 1994) TIPSY(1)
projection 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 functions 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
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