[vtkusers] help with contouring selected cells using vtkContourFilter
smahaade at essence.utsi.edu
Fri Apr 18 15:44:27 EDT 2003
I want to contour a huge structured grid. I wanted to speed up the
contouring in vtkContourFilter. I already know the cells that I want to
contour. They are sporadic and distributed all over the structured grid.
So I supplied an additional data member, a vtkIdList, to the vtkContourFilter
class that helps to check whether a cell in the grid needs to be contoured or
not. Each number contained in the vtkIdList is either a 1 or 0 depending on
whether the corresponding cell in the structured grid is a cell that needs to
be contoured or not. (if out of 10 cells cells 0,1,5,7 are the only cells
that need to be contoured then the vtkIdList will contain the numbers
class VTK_EXPORT vtkContourFilter : public vtkDataSetToPolyDataFilter
void vtkContourFilter::SetIdList(vtkIdList *celList)
this->cList = celList;
// for use in the Execute function later
for (int j=0; j < numCells && !abortExecute&& this->cList->GetId(j)
==1 ; j++)
/*** cell selection in the for loop condition *********/
for (i=0; i < numContours; i++)
cell->Contour(values[i], cellScalars, this->Locator,
newVerts, newLines, newPolys, inPd, outPd,
inCd, cellId, outCd);
} // for all contour values
} // for all cells
} //if using scalar tree
I thought that this would speed up the contouring process. Instead it
slows it down. The result is 2 TIMES slower than contouring all the cells in
the entire grid. (even though I am contouring only half the number of cells
in the entire grid).
I am unable to understand the cause for this.
Does anyone know what is going wrong here ?
Does anyone know a better way to contour selected cells using ContourFilter ?
I have been stuck at this for a long time.
Any help is greatly appreciated.
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