[vtkusers] [Edit]: UGrid volume ray cast Bug?

[Randall Hand]

If you look at the documentation for vtkVolumeProperty around the
SetIndependantComponents stuff :
http://www.vtk.org/doc/release/5.0/html/a02182.html#z4350_1

I'll play around with it tomorrow morning.. if I can get a working version
of your test driver, I'll send it to you for you to check out :)

On 4/5/06, Juan José Aja Fernández <juan.aja at gmail.com> wrote:
>
> Hi, Randall:
>
> Thanks again for the swift response.
>
> I haven't tried using point data, first thing tomorrow I will rewrite the
> code.
>
> Your second suggestion was exactly what I was looking for, until now I
> didn't know if there was a way to color whithout using a transfer function
> (that explains my horrible hack of using the voxel index as a "scalar"). I
> skimmed through the docs trying to find something related, and I looked at
> vtkScalarsToColors as a possible candidate, but I have my doubts: ¿How can I
> create a RGBA scalar field and how can this be used as the color function in
> the mapper?
>
>
> Thanks a lot,
>
> Juan.
>
>
>
> On 4/5/06, Randall Hand <randall.hand at gmail.com> wrote:
> >
> > I'll try this out on my end tomorrow, since I'm already neck-deep in the
> > Volume Rendering code anyway :)
> >
> > Just a thought tho, I believe most of the Volume Renderers expect Point
> > Data, not Cell Data.. Have you tried using Per-point data?
> >
> > Also, if you really want to define colors per-point and not via a
> > colormap, then if you use a 4-component scalar field you can have it
> > directly contain R/G/B/A for volume rendering.
> >
> >  On 4/5/06, Juan José Aja Fernández <juan.aja at gmail.com> wrote:
> >
> > > (Sorry for the double post, The first url was broken)
> >
> > Hi, Everyone:
> >
> > This is the third time I'm posting about this issue, of the previous two
> > one remained unanswered and the last one I've got a kind response by Randall
> > Hand: http://public.kitware.com/pipermail/vtkusers/2006-February/083786.html
> >
> >
> >  who pointed me in the direction of this fixed bug:
> >
> > http://www.vtk.org/Bug/bug.php?op=show&bugid=2546&pos=3 but the problem
> > persists.
> >
> > I think the vtkUnstructuredGridVolumeRayCastMapper has some serious bug
> > (look at the screenshots posted in the thread that Randall answered), and to
> > prove It I think I need to post my entire example code:
> >
> > (Really, I think I'm on to something, specially If you consider that the
> > mapper for unstructured grids is fairly new, but I didn't want to litter the
> > bug report with false positives).
> >
> >
> > #include "vtkVoxel.h"
> > #include "vtkCellData.h"
> > #include "vtkRenderer.h"
> > #include "vtkPoints.h"
> > #include "vtkUnstructuredGrid.h"
> > #include "vtkRenderWindow.h"
> > #include "vtkRenderWindowInteractor.h"
> > #include "vtkColorTransferFunction.h"
> > #include "vtkPiecewiseFunction.h"
> > #include "vtkVolume.h"
> > #include "vtkVolumeProperty.h"
> > #include "vtkUnstructuredGridWriter.h"
> > #include "vtkDoubleArray.h"
> > #include "vtkDataSetTriangleFilter.h"
> > #include "vtkUnstructuredGridVolumeRayCastMapper.h"
> > #include "vtkUnstructuredGridVolumeRayCastFunction.h"
> > #include "vtkImageData.h"
> > #include "vtkDataSetToImageFilter.h"
> > #include "stdio.h"
> > #include "iostream.h"
> > #include "fstream.h"
> > #include "string.h"
> > #include "vtkOpenGLRenderer.h"
> > #include "vtkXOpenGLRenderWindow.h"
> > #include "vtkXRenderWindowInteractor.h"
> >
> >
> > int main(int argc, char *dim[])
> > {
> >
> >   int dim_x =  atoi(dim[1]);
> >   int dim_y =  atoi(dim[1]);
> >   int dim_z =  atoi(dim[1]);
> >   int i, j, k;
> >   int no_points = dim_x * dim_x * dim_x;
> >   int no_voxels = (dim_x-1) * (dim_x-1) * (dim_x-1);
> >
> >   vtkPoints *points = vtkPoints::New();
> >   points->SetNumberOfPoints(no_points);
> >   points->SetDataTypeToDouble();
> >
> >   for(k=0; k< dim_z; k++)
> >     for(j=0; j< dim_y; j++)
> >       for(i=0; i< dim_x; i++)
> >         points->InsertNextPoint(i, j, k);
> >
> >   vtkDoubleArray *pts = vtkDoubleArray::New();
> >   pts->SetName("pts");
> >
> >   for(i=0; i < no_voxels; i++)
> >     pts->InsertNextValue(i);
> >
> >   vtkUnstructuredGrid *grid = vtkUnstructuredGrid::New();
> >
> >   vtkColorTransferFunction *funtrans = vtkColorTransferFunction::New();
> >
> >   //To create the grid we need to know if we are in any of the
> >   //cube limits (height, width, depth), to prevent from adding
> >   //inexistant cells
> >   j=0;
> >   k=0;
> >   int w = 0;
> >   int count = 0;
> >   vtkVoxel *v = vtkVoxel::New();
> >
> >   for(i=0; i< (no_points - ((dim_x * dim_x) + (dim_x + 1))); i++) {
> >     if(j != dim_x - 1 && k!= dim_x - 1) {
> >       (v->GetPointIds())->SetId(0, i);
> >       (v->GetPointIds())->SetId(1, i+1);
> >       (v->GetPointIds())->SetId(2, i+dim_x);
> >       (v->GetPointIds())->SetId(3, i+dim_x+1);
> >       (v->GetPointIds())->SetId(4, i + (dim_x * dim_y));
> >       (v->GetPointIds())->SetId(5, i + (dim_x * dim_y) + 1);
> >       (v->GetPointIds())->SetId(6, i + (dim_x * dim_y) + dim_x);
> >       (v->GetPointIds())->SetId(7, i + (dim_x * dim_y) + dim_x + 1);
> >       grid->InsertNextCell(v->GetCellType(), v->GetPointIds());
> >
> >       j++;
> >       count++;
> >     }
> >     else {
> >       if(j == dim_x-1) {
> >         j=0;
> >         k++;
> >         if(k == dim_x-1) {
> >           j=0;
> >           k=0;
> >           i = i+dim_x;
> >           w++;
> >         }
> >       }
> >     }
> >   }
> >   grid->SetPoints(points);
> >
> >   vtkCellData *cd = grid->GetCellData();
> >   cd->SetNumberOfTuples(no_voxels);
> >   cd->SetScalars(pts);
> >
> >   int idx = 0;
> >   while (idx < no_voxels) {
> >     if (idx%2 == 0 )
> >
> >       funtrans->AddRGBPoint(pts->GetValue(idx), 1, 0, 0);
> >     else funtrans->AddRGBPoint(pts->GetValue(idx), 0, 1,0);
> >
> >     idx++;
> >   }
> >   vtkOpenGLRenderer *renderer = vtkOpenGLRenderer::New();
> >   vtkXOpenGLRenderWindow *renwin =  vtkXOpenGLRenderWindow::New();
> >   vtkXRenderWindowInteractor *iren = vtkXRenderWindowInteractor::New();
> >
> >   renwin->AddRenderer(renderer);
> >   iren->SetRenderWindow(renwin);
> >
> >   vtkPiecewiseFunction *funop = vtkPiecewiseFunction::New();
> >   funop->AddPoint(0, 1);
> >   funop->AddPoint(no_voxels, 1);
> >
> >   vtkVolumeProperty *vp = vtkVolumeProperty::New();
> >   vp->SetColor(funtrans);
> >   vp->SetScalarOpacity(funop);
> >
> >   vtkUnstructuredGridVolumeRayCastMapper *vrcm =
> > vtkUnstructuredGridVolumeRayCastMapper::New();
> >
> >   vtkDataSetTriangleFilter *filter = vtkDataSetTriangleFilter::New();
> >   filter->SetInput(grid);
> >
> >   vrcm->SetInput(filter->GetOutput());
> >
> >   vtkVolume *volume = vtkVolume::New();
> >   volume->SetMapper(vrcm);
> >   volume->SetProperty(vp);
> >
> >   renderer->AddActor(volume);
> >
> >   renwin->Render();
> >   iren->Start();
> > }
> >
> >
> > This will attempt to create a cube with dimensions arg[1] coloring odd
> > and even cells with green and red.
> > Try it with argv[1] = 6, then argv[1] = 20, see the results.
> >
> > Is this a bug, or I'm doing things the wrong way?
> >
> >
> > Thanks in advance,
> >
> > Juan.
> >
> >
> > _______________________________________________
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> >
> >
> >
> >
> >
> > --
> > Randall Hand
> > Visualization Scientist,
> > ERDC-MSRC Vicksburg, MS
> > Homepage: http://www.yeraze.com
> >
>
>


--
Randall Hand
Visualization Scientist,
ERDC-MSRC Vicksburg, MS
Homepage: http://www.yeraze.com
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