[vtkusers] Help

[David Doria]

>
>  1.where is (0,0,0) or where is the origin?
>

You can add a sphere source at (0,0,0) to see where it is:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/GeometricObjects/Sphere
<http://www.vtk.org/Wiki/VTK/Examples/Cxx/GeometricObjects/Sphere>

>  2.Can you help me do some improvement?This example uses a picture drawed
> by the code itself.How to improve the code to load a file of .ply and then
> get coordinate value?
>

Here is an example of how to load a ply file:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/IO/ReadPLY
<http://www.vtk.org/Wiki/VTK/Examples/Cxx/IO/ReadPLY>

>  3.This program only demonstrates the coordinate value when I click at
> somewhere.How to improve the code to get normal vector of every triangle
> which is made up by three points?
>

You can use:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataExtractNormals
<http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataExtractNormals>along
with
http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataCellNormals

<http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataCellNormals>to
get the triangle normals.

Good luck,

David
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