[vtkusers] Computational Geometry - user equations?

[Gib Bogle]

Hi Piers, Andrew, Cory,

This does not build with VTK 5.10 (no vtkNamedColors.h).  Is there a version that works with 5.10?

Thanks
Gib
________________________________
From: vtkusers [vtkusers-bounces at vtk.org] on behalf of piers.barber at logicmonkey.co.uk [piers.barber at logicmonkey.co.uk]
Sent: Sunday, 4 October 2015 1:48 p.m.
To: andrew.amaclean at gmail.com
Cc: vtk
Subject: Re: [vtkusers] Computational Geometry - user equations?


Andrew, Cory,

Thanks for the attachment - as a non-coder it bridged the gap between the PDF that I've seen before and what actually needed to be done.

I've attached my trefoil knot code in a zip. The partial derivatives make a big difference to shadows.

I'm on Arch Linux with VTK 6.1.0, and the only change I needed to make to get the example to build was to the CMakeLists.txt - so it picks up OpenGL rather than OpenGL2.

I'm pleased that this works, but the output surface is rather jagged when compared to what I get with MathMod. Any ideas?

For the VTK user list, the zipped files I mention are here:

https://github.com/logicmonkey/curves/tree/master/vtk/TrefoilKnot

( unzip/git pull; cd TrefoilKnot; mkdir build; cd build; cmake ..; make; ./bin/TrefoilKnot )

Thanks again for your help.

--

Piers Barber (-=:LogicMonkey;=-)

On 2015-10-01 00:19, Andrew Maclean wrote:

If I understand you correctly, then the approach described in http://www.vtk.org/img/ParametricSurfaces.pdfin " How to create your own surface" should work for you. If you adopt this approach, you just build using the library and you do not need to modify the VTK library.

I attach  a VTK 6.3+ version of the example for you to try out.

I'll add this to the VTK examples sometime next week.

Once you get a surface you might like to look at:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Visualization/ElevationBandsWithGlyphs
and
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Visualization/CurvatureBandsWithGlyphs
for some visualisation ideas.


Regards
   Andrew



---------- Forwarded message ----------
From: Cory Quammen <cory.quammen at kitware.com<mailto:cory.quammen at kitware.com>>
To: piers.barber at logicmonkey.co.uk<mailto:piers.barber at logicmonkey.co.uk>
Cc: "vtkusers at vtk.org<mailto:vtkusers at vtk.org>" <vtkusers at vtk.org<mailto:vtkusers at vtk.org>>
Date: Wed, 30 Sep 2015 09:15:45 -0400
Subject: Re: [vtkusers] Computational Geometry - user equations?
On Tue, Sep 29, 2015 at 12:13 PM, <piers.barber at logicmonkey.co.uk<mailto:piers.barber at logicmonkey.co.uk>> wrote:
Hi All,

I'd like to specify a surface f(u,v) in 3D with my own parametric equation system {x(u,v), y(u,v), z(u,v)}. And then visualize it.

The only way I can see to do this is to add my function to the library source code, build the library and then call my function as described here:

http://www.vtk.org/Wiki/VTK/Examples/Cxx/GeometricObjects/ParametricObjectsDemo#CMakeLists.txt

Yep, that looks like a good way to go.

I'm using vtkParametricTorus[.h, .cxx] as a template, but is there an easier and more direct way to do this?

You can define your subclass of vtkParametricFunction in your local project - no need to add it to VTK, which is what I think you were saying above.

Were you looking for a vtkParametricFunction subclass that takes an expression for x(u,v), etc.? That doesn't exist as far as I know, but that would be cool to have.

Cory

Thanks!

-=:LM:=-
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--
Cory Quammen
R&D Engineer
Kitware, Inc.


--
___________________________________________
Andrew J. P. Maclean

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