[Python-apps-team] Bug#488496: mayavi2: streamlines don't cross boundaries

[Francesco Poli]

Package: mayavi2
Version: 2.1.1-5
Severity: wishlist

Hi!

Streamlines don't seem to be able to cross interblock boundaries.
This is a really annoying limitation: I would like to see streamlines
starting from a seed in one PLOT3D data block and extending into
other loaded PLOT3D data blocks, if the vector field is such that
the streamline should do so...

I'll try and explain a little better.

Let's consider the attached gzipped tar archive (which includes a
test PLOT3D geometry+solution pair of files, along with a Fortran77
program that generates it):

  $ tar xvzf fh_3d_testcase.tar.gz 
  fakehurr_3D.q
  fakehurr_3D.xyz
  gen_fakehurr.f
  $ mayavi2

The main window shows up.

 * from menus, select File -> Load data -> PLOT3D file
 * as XYZ Co-ordinate file, select `fakehurr_3D.xyz'
 * as Q Solution file, select `fakehurr_3D.q'
 * in the Edit PLOT3DReader properties dialog window, check "Binary
file", "Do not reduce number of outputs", "Has byte count", and "Multi
grid"; *un*check "Force read", "I blanking", and "Two dimensional
geometry"; select "little_endian" Byte order; click on the OK button
 * from menus, select Visualize -> Filters -> Select Output
 * from menus, select Visualize -> Modules -> GridPlane
 * in the MayaVi pane, left-click on the GridPlane and select "z" Axis
in the MayaVi object editor pane: a semicircular mesh appears
 * in the MayaVi pane, left-click on SelectOutput and then right-click;
from the popup menu, select Copy
 * in the MayaVi pane, left-click on
PLOT3D:fakehurr_3D.xyz, fakehurr_3D.q and then right-click; from
the popup menu, select Paste
 * in the MayaVi pane, left-click on the newly created SelectOutput and
drag the slider in the MayaVi object editor pane (so that output #1 is
selected, rather than #0)
 * in the TVTK Scene 1 pane, click on "Obtain an isometric view" button

Now I would like to display streamlines that (given the vector field
of this test case) should assume a helical-like shape.

 * from menus, select Visualize -> Modules -> Streamline

Now, no matter how I move the seeds or change integration parameters,
streamlines never exceed a half turn in longitudinal angle range.
That is to say: they do not cross the data block boundaries and so
they fail to extend to the other block...

I think there should (at least) be an option to enable this boundary
crossing behavior: if a single integration step takes the streamline
from a block to another one, then the integration should go on
in the other block.
I also think this option should be enabled by default...

I am not sure this can be implemented at the MayaVi2 level, or should
be implemented at the VTK level.

Please forward to MayaVi2 upstream or reassign to package vtk,
as appropriate.
Thanks in advance.


-- System Information:
Debian Release: lenny/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.24-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages mayavi2 depends on:
ii  libc6                        2.7-10      GNU C Library: Shared libraries
ii  python                       2.5.2-1     An interactive high-level object-o
ii  python-central               0.6.7       register and build utility for Pyt
ii  python-enthought-traits      2.0.4-2     Manifest typing and reactive progr
ii  python-enthought-traits-ui   2.0.4-3     User interface related modules for
ii  python-numpy                 1:1.1.0-1   Numerical Python adds a fast array
ii  python-pkg-resources         0.6c8-3     Package Discovery and Resource Acc
ii  python-vtk                   5.0.4-1+b1  Python bindings for VTK
ii  python-wxgtk2.6              2.6.3.2.2-2 wxWidgets Cross-platform C++ GUI t
ii  python2.5                    2.5.2-6     An interactive high-level object-o

mayavi2 recommends no packages.

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