[vtkusers] WG: Fwd: Re: Glyph coloring by vector magnitud

[Sebastian Gatzka]

Hello again.

I had a quick look into the example
There were different things "wrong"

    * There had to be some vector components you set to the points.
    * The code you commented with "//create anything you want here, we
      will use a cube for the demo" is crucial to the glyph.
      It desribes how the glyh will look like. If you set a cube the
      glyp tip will look like a cube.
      If you set a sphere the glyph tip will look like a sphere. So an
      arrow is the choice here.

So now there a three arrows displayed at the three points.
But they are not colored. *The transformation from color information 
(having three components) to scalar informations (having one component) 
the coloring can be done with is not known to me.*
Hope you have an answere to that. The current example code looks like 
this - I haven't updated the wiki page yet, because it's not coloring so 
far - only displaying the glyphs.

#include <vtkSmartPointer.h>
#include <vtkPointData.h>
// #include <vtkCubeSource.h>
#include <vtkPolyData.h>
#include <vtkPoints.h>
#include <vtkGlyph3D.h>
#include <vtkCellArray.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkUnsignedCharArray.h>
#include <vtkArrowSource.h>

int exampleColorGlyphs()
{
   //create points
   vtkSmartPointer<vtkPoints> points =
       vtkSmartPointer<vtkPoints>::New();
   points->InsertNextPoint(0,0,0);
   points->InsertNextPoint(1,0,0);
   points->InsertNextPoint(2,0,0);

   //create vector components
   vtkSmartPointer<vtkUnsignedCharArray> vectors =
       vtkSmartPointer<vtkUnsignedCharArray>::New();
   vectors->SetName("Vectors");
   vectors->SetNumberOfComponents(3);
   vectors->InsertNextTuple3(1,1,0);
   vectors->InsertNextTuple3(0,1,0);
   vectors->InsertNextTuple3(0,0,1);

   //setup scales
   vtkSmartPointer<vtkUnsignedCharArray> colors =
       vtkSmartPointer<vtkUnsignedCharArray>::New();
   colors->SetName("colors");
   colors->SetNumberOfComponents(3);
   unsigned char r[3] = {255,0,0};
   unsigned char g[3] = {0,255,0};
   unsigned char b[3] = {0,0,255};
   colors->InsertNextTupleValue(r);
   colors->InsertNextTupleValue(g);
   colors->InsertNextTupleValue(b);

   //combine into a polydata
   vtkSmartPointer<vtkPolyData> polydata =
       vtkSmartPointer<vtkPolyData>::New();
   polydata->SetPoints(points);
   //polydata->GetPointData()->SetScalars(colors);
   polydata->GetPointData()->SetVectors(vectors);

   vtkSmartPointer<vtkArrowSource> arrow =
       vtkSmartPointer<vtkArrowSource>::New();

   vtkSmartPointer<vtkGlyph3D> glyph3D =
       vtkSmartPointer<vtkGlyph3D>::New();
   glyph3D->SetColorModeToColorByScalar();
   glyph3D->SetSourceConnection(arrow->GetOutputPort());
   glyph3D->SetInput(polydata);
   glyph3D->Update();

   //Create a mapper and actor
   vtkSmartPointer<vtkPolyDataMapper> mapper =
       vtkSmartPointer<vtkPolyDataMapper>::New();
   mapper->SetInputConnection(glyph3D->GetOutputPort());
   vtkSmartPointer<vtkActor> actor =
       vtkSmartPointer<vtkActor>::New();
   actor->SetMapper(mapper);

   //Create a renderer, render window, and interactor
   vtkSmartPointer<vtkRenderer> renderer =
       vtkSmartPointer<vtkRenderer>::New();
   vtkSmartPointer<vtkRenderWindow> renderWindow =
       vtkSmartPointer<vtkRenderWindow>::New();
   renderWindow->AddRenderer(renderer);
   vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
       vtkSmartPointer<vtkRenderWindowInteractor>::New();
   renderWindowInteractor->SetRenderWindow(renderWindow);

   //Add the actor to the scene
   renderer->AddActor(actor);
   renderer->SetBackground(1,1,1); // Background color white

   //Render and interact
   renderWindow->Render();
   renderWindowInteractor->Start();

   return 0;
}

Am 05.03.2010 21:55, schrieb David Doria:
> On Fri, Mar 5, 2010 at 3:35 PM, Sebastian Gatzka 
> <sebastian.gatzka at stud.tu-darmstadt.de 
> <mailto:sebastian.gatzka at stud.tu-darmstadt.de>> wrote:
>
>     Obviously there was nothing wrong.
>
>     When we moved on from this “constructed” example to the real
>     application we are working with everything went fine.
>
>     All Vectors are scales and colored now!
>
>
> Do you think you could fix this example?
>
> http://www.vtk.org/Wiki/VTK/Examples/Visualization/ColorGlyphs
>
> Thanks,
>
> David
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