[vtkusers] Re: vtk and python for large amout of data

[Marcus Stojek]

Hi,
thanks a lot for the answers. Understanding this SetVoidArray function
helps. Now I am pretty close to what I need, but still there is a small
problem with vtkPoints.SetData()

Although I think I did everything correct, there seems to be a problem
with NumberOfPoints(). With GetPoint(id) I get the right coordinates for
all Points, but still NumberOfPoints is 1. Below you will find my small
example code. Any idea?

Thanks,
marcus


Python 2.2.1
Numeric 21.0b1
Windows NT

#----snip-------------------------------------------------------------------
import Numeric

        narray   = Numeric.array((0,0,0, 4,0,0, 0,4,0, 0,0,4
,3,8,0),Numeric.Float32)
        nnum     = 5
        earray   = Numeric.array((4,0,1,2,3, 4,4,2,3,1),Numeric.Int32)
        ctarray  = Numeric.array((10,10),'char')
        locarray = Numeric.array((0,5),Numeric.Int32)
        enumber  = 2

#idtypes
        IdTArray=vtkIdTypeArray()
        IdTArray.SetVoidArray(earray,enumber,1)

#celltypes
        cidTArray=vtkUnsignedCharArray()
        cidTArray.SetVoidArray(ctarray,enumber,1)
#cell array
        vtkCArray=vtkCellArray()
        vtkCArray.SetCells(enumber,IdTArray)
#cell location
        vtkLocArray=vtkIntArray()
        vtkLocArray.SetVoidArray(locarray,enumber,1)
#grid
        grid=vtkUnstructuredGrid()
        grid.SetCells(cidTArray,vtkLocArray,vtkCArray)
#points
        vpoints=vtkFloatArray()
        vpoints.SetNumberOfComponents(3)
        vpoints.SetVoidArray(narray,nnum,1)

##########################
 #  #  ####  #    ####
 #  #  #     #    #  #
 ####  ####  #    ####
 #  #  #     #    #
 #  #  ####  #### #
        pointe = vtkPoints()
#This does not work because NumberOfPoints is wrong
        pointe.SetData(vpoints)
#This does work:
        #pointe.SetNumberOfPoints(5)
        #pointe.SetPoint(0, 0,0,0)
        #pointe.SetPoint(1, 4,0,0)
        #pointe.SetPoint(2, 0,4,0)
        #pointe.SetPoint(3, 0,0,4)
        #pointe.SetPoint(4, 3,8,0)
        print 'Number of points',pointe.GetNumberOfPoints()
        print 'Probe point',pointe.GetPoint(2)
###########################
        grid.SetPoints(pointe)

        win = wxMDIChildFrame(self.parent, -1, 'test')
        widget = wxVTKRenderWindow.wxVTKRenderWindow(win, -1)

        MapperSurf=vtkDataSetMapper()
        MapperSurf.SetInput(grid)
        MapperSurf.ScalarVisibilityOff()
        ActorSurf=vtkActor()
        ActorSurf.SetMapper(MapperSurf)
        PropSurf=vtkProperty()
        PropSurf.SetDiffuseColor(0.7,0.7,0.7)
        PropSurf.SetRepresentationToSurface()
        PropSurf.BackfaceCullingOff()
        PropSurf.FrontfaceCullingOff()
        ActorSurf.SetProperty(PropSurf)

        ren = vtkRenderer()
        widget.GetRenderWindow().AddRenderer(ren)
        ren.AddActor(ActorSurf)

        widget.Render()
        widget.Show(true)
#--snip---------------------------------------------------------------------


>Unfortunately, to create an unstructured grid, you have to use the
>following method:
>
>void vtkUnstructuredGrid::SetCells(vtkUnsignedCharArray *cellTypes,
>                                   vtkIntArray *cellLocations,
>                                   vtkCellArray *cells);
>
>This means that you have to compute cellTypes, cellLocations and cells.
>This is because the following is not wrapped:
>
>void  vtkUnstructuredGrid::SetCells(int *types, vtkCellArray *cells);
>
>(since it takes a pointer to a variable length in array).
>
>-Berk