[vtkusers] Feedback about switching from Java3D to VTK for a Java CAE application

[Jerome Robert]

Hi all,

jCAE is an LGPL Java based application to display and mesh IGES and STEP
geometries. We have just released jCAE 0.16 which is the first version using the
Java wrapper of VTK. Previous versions were based on Java3D; we decided to
switch to VTK because some key features are missing in Java3D, mainly for
picking. We are very pleased by the end result, many thanks to all VTK
developers for providing this amazing product. We needed to somehow patch VTK to
successfully integrate it with jCAE, and submitted all of our patches to VTK bug
tracker:

   * 6723 [Java wrapper] Symbols containing '_' character are unavailable
Name-mangling scheme is described in JNI specification, underscores in symbol
names are special characters and must be escaped as '_1'. Current code throws an
exception when such a symbol is used.

   * 7111 [Performance] Picking large polydatas with vtkVisibleCellSelector is
slow
We use vtkVisibleCellSelector to select triangles from a triangular mesh.
Display list is always recompiled after a selection, which takes a lot of time
with our meshes (more than 1 million triangles).

   * 7236 vtkOpenGLRenderWindow::SetRGBACharPixelData overwrites z-buffer Bug
fixed in 5.2 and HEAD, thanks!

   * 7294 Make offset parameters of vtkMapper non static
Allows having different GL_OFFSET for each actors.

   * 7295 Allow picking translucent actors

   * 7296 [Performance] Not erasing Z-buffer on selection rendering
Reuse normal rendering Z-buffer to speed up rendering picking.

   * 7521 [Performance] Allow disabling lighting for an actor
This is useful for us for performance reason.

We are maintaining these patches against 5.2 and HEAD branches, and will try to
update patches in VTK bug tracker from time to time, but we will be very glad if
they could be committed and are willing to help if needed.

  Home site:
  * http://jcae.sourceforge.net

  Related VTK bugs and feature enhancements requests:
  * http://www.vtk.org/Bug/view.php?id=6723
  * http://www.vtk.org/Bug/view.php?id=7111
  * http://www.vtk.org/Bug/view.php?id=7236
  * http://www.vtk.org/Bug/view.php?id=7294
  * http://www.vtk.org/Bug/view.php?id=7295
  * http://www.vtk.org/Bug/view.php?id=7296
  * http://www.vtk.org/Bug/view.php?id=7521

  Patches:
  * http://jcae.svn.sourceforge.net/viewvc/jcae/trunk/vtk-util/patch/

Thanks again for providing VTK to the community.

Regards,

Jerome