[vtkusers] Are there limitations in vtkDelaunay2D?

[Tanweer Rashid]

Hi,

I am trying to generate triangles from sets of points. I am using
vtkDelaunay2D for this. For some pointsets, vtkDelaunay2D is not generating
any triangles. Following is the code I am using. I am basically creating a
vtkPolyData using the points, and then applying vtkDelaunay2D on that
polydata. Lastly, I am visualizing the output.




        #include <stdio.h>
        #include <iostream>
        #include <fstream>

        #include <vtkSmartPointer.h>
        #include <vtkIdList.h>
        #include <vtkCellArray.h>
        #include <vtkPoints.h>
        #include <vtkPolyData.h>
        #include <vtkActor.h>
        #include <vtkPolyDataMapper.h>
        #include <vtkRenderer.h>
        #include <vtkRenderWindow.h>
        #include <vtkRenderWindowInteractor.h>
        #include <vtkDelaunay2D.h>
        #include <vtkPolyDataWriter.h>

        using namespace std;

        int main() {
            int pointIndex[] = {0, 1, 2, 3};

            // Points
            double **pts = new double*[3];
            pts[0] = new double[3] {8.53125, 7.53125, 1.53125};
            pts[1] = new double[3] {8.53125, 7.53125, 2.53125};
            pts[2] = new double[3] {8.26562, 8.26562, 2.53125};
            pts[3] = new double[3] {8.26562, 8.26562, 1.53125};

            vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
            vtkSmartPointer<vtkIdList> pointList =
vtkSmartPointer<vtkIdList>::New();

            for (int i = 0; i < 4; i++) {
                points->InsertPoint(i, pts[i][0], pts[i][1], pts[i][2]);
                pointList->InsertNextId(i);
            }

            vtkSmartPointer<vtkCellArray> vertexArray =
vtkSmartPointer<vtkCellArray>::New();
            vertexArray->InsertNextCell(pointList);

            vtkSmartPointer<vtkPolyData> pdata =
vtkSmartPointer<vtkPolyData>::New();
            pdata->SetPoints(points);
            pdata->SetVerts(vertexArray);

            vtkSmartPointer<vtkDelaunay2D> del =
vtkSmartPointer<vtkDelaunay2D>::New();
            del->SetProjectionPlaneMode(VTK_BEST_FITTING_PLANE);
            del->SetInput(pdata);
            del->Update();

            vtkSmartPointer<vtkPolyData> output = del->GetOutput();
            cout << "Number of cells: " << output->GetNumberOfCells() <<
endl;
            cout << "Number of points: " << output->GetNumberOfPoints() <<
endl;

            vtkSmartPointer<vtkPolyDataMapper> mapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
            mapper->SetInput(output);

            vtkSmartPointer<vtkActor> actor =
vtkSmartPointer<vtkActor>::New();
            actor->SetMapper(mapper);

            vtkSmartPointer<vtkRenderer> ren =
vtkSmartPointer<vtkRenderer>::New();
            vtkSmartPointer<vtkRenderWindow> renwin =
vtkSmartPointer<vtkRenderWindow>::New();
            vtkSmartPointer<vtkRenderWindowInteractor> iren =
vtkSmartPointer<vtkRenderWindowInteractor>::New();

            renwin->AddRenderer(ren);
            iren->SetRenderWindow(renwin);
            ren->AddActor(actor);

            renwin->Render();
            iren->Start();

            return 0;
        }



For the 4 points in the code, I am not getting any triangulations. Can
someone tell me why? I was wondering if this is because of some kind of
limitation with vtkDelaunay2D or perhaps because my code is incorrect. Any
help is appreciated.

-- 
Tanweer Rashid
MSVE Dept.
Old Dominion University
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