[vtkusers] Texture mapping

[David Gobbi]

Hi Remo,

Just set up your points & your polygons so that the triangles don't share
any points.  Waste a bit of memory, in other words.

 - David

On Fri, 29 Jun 2001, Remo Ziegler wrote:

> Hi David,
>
> thanks a lot for your help. Do you know how I can map one 3D-point on several texture-points? The
> problem is, that every triangle is stored independently from the other in the texture file, so
> that a 3Dpoint can be mapped on several different positions in the texture file.
>
> Thanks a lot for your help again!!
>
> Greets .... Remo
>
> David Gobbi wrote:
>
> > Hi Remo,
> >
> > It's about the same in VTK.  In a situation where you already have
> > the vertices & texture coords, you can build a vtkPolyData like this:
> >
> > points = vtkPoints::New();
> > points->InsertNextPoint(x,y,z)  // repeat for all points
> > ...
> >
> > polys = vtkCellArray::New();
> > polys->InsertNextCell(n);       // n is number of points in polygon
> > polys->InsertCellPoint(i);      // i is index into above 'points' list
> > polys->InsertCellPoint(j);      // etc. for each point in polygon
> > ...
> > polys->InsertNextCell(m);       // next polygon
> > ...
> >
> > tcoords = vtkTCoords::New();
> > tcoords.InsertNextTCoord(tx,ty,0.0); // one tcoord per point
> > ...
> >
> > data = vtkPolyData::New();
> > data->SetPoints(points);
> > data->SetPolys(polys);
> > data->GetPointData()->SetTCoords(tcoords);
> >
> > Done!  If you want to set normals for the points, you do it
> > the same way as for the TCoords.
> >
> >  - David
> >
> > --
> >   David Gobbi, MSc                       dgobbi at irus.rri.ca
> >   Advanced Imaging Research Group
> >   Robarts Research Institute, University of Western Ontario
> >
> > On Fri, 29 Jun 2001, Remo Ziegler wrote:
> >
> > > Hi,
> > >
> > > I have a vtkPolyData object describing the polygonal  model and a
> > > bmp-File to describe the texture for it. Since the texture file has a
> > > certain structure, I want to map every triangle of vtkPolyData to a
> > > triangle in the bmp-file describing the texture.
> > > In OpenGL I would use the glTextCoord2f(..., ....); glVertex3f(...,
> > > ...., ....); construction ... is there any similar stuff in vtk?
> > >
> > > Thanks for your help! Have a nice weekend !!
> > >
> > > Greets .... Remo
> > >
> > >
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