# ContoursFromPolyData

VTKExamples/CSharp/Filtering/ContoursFromPolyData

### Description

This example uses vtkCutter to generate contours from a PolyData. A vtkPlane is set at the center of the PolyData and several contours are generated by specifying contour values that are distances to the center plane. The example works with a filename if provided. Otherwise is uses a vtkSphereSource.

A tutorial on how to setup a Windows Forms Application utilizing ActiViz.NET can be found here: Setup a Windows Forms Application to use ActiViz.NET
Note: As long as ActiViz.NET is not build with VTK version 6.0 or higher you must define the preprocessor directive VTK_MAJOR_VERSION_5.

### Code

ContoursFromPolyData.cs

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Windows.Forms;
    using System.Diagnostics;

    using Kitware.VTK;

    namespace ActiViz.Examples {
       public partial class Form1 : Form {
          public Form1() {
             InitializeComponent();
          }

          private void renderWindowControl1_Load(object sender, EventArgs e) {
             try {
                ContoursFromPolyData(null);
                //ContoursFromPolyData(@"c:\vtk\vtkdata-5.8.0\Data\bunny.vtp");
             }
             catch(Exception ex) {
                MessageBox.Show(ex.Message, "Exception", MessageBoxButtons.OK);
             }
          }

          private void ContoursFromPolyData(string filePath) {
             vtkPolyData inputPolyData;
             if(filePath != null) {
                vtkXMLPolyDataReader reader = vtkXMLPolyDataReader.New();
                reader.SetFileName(filePath);
                reader.Update();
                inputPolyData = reader.GetOutput();
             }
             else {
                vtkSphereSource sphereSource = vtkSphereSource.New();
                sphereSource.SetThetaResolution(30);
                sphereSource.SetPhiResolution(15);
                sphereSource.Update();
                inputPolyData = sphereSource.GetOutput();
             }

             vtkPolyDataMapper inputMapper = vtkPolyDataMapper.New();
    #if VTK_MAJOR_VERSION_5
             inputMapper.SetInput(inputPolyData);
    #else
             inputMapper.SetInputData(inputPolyData);
    #endif

             // Create a plane to cut
             vtkPlane plane = vtkPlane.New();
             double[] center = inputPolyData.GetCenter();
             double[] bounds = inputPolyData.GetBounds();
             plane.SetOrigin(center[0], center[1], center[2]);
             plane.SetNormal(1, 1, 1);

             float[] centerf = new float[] { (float)center[0], (float)center[1], (float)center[2] };
             float[] minBoundf = new float[] { (float)bounds[0], (float)bounds[2], (float)bounds[4] };
             float[] maxBoundf = new float[] { (float)bounds[1], (float)bounds[3], (float)bounds[5] };
             IntPtr pCenter = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(float)) * 3);
             IntPtr pMinBound = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(float)) * 3);
             IntPtr pMaxBound = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(float)) * 3);
             Marshal.Copy(centerf, 0, pCenter, 3);
             Marshal.Copy(minBoundf, 0, pMinBound, 3);
             Marshal.Copy(maxBoundf, 0, pMaxBound, 3);

             // vtkMath.Distance2BetweenPoints accepts floats only
             double distanceMin = Math.Sqrt(vtkMath.Distance2BetweenPoints(pMinBound, pCenter));
             double distanceMax = Math.Sqrt(vtkMath.Distance2BetweenPoints(pMaxBound, pCenter));

             Marshal.FreeHGlobal(pCenter);
             Marshal.FreeHGlobal(pMinBound);
             Marshal.FreeHGlobal(pMaxBound);
             // Create cutter
             vtkCutter cutter = vtkCutter.New();
             cutter.SetCutFunction(plane);
    #if VTK_MAJOR_VERSION_5
             cutter.SetInput(inputPolyData);
    #else
             cutter.SetInputData(inputPolyData);
    #endif
             cutter.GenerateValues(20, -distanceMin, distanceMax);
             vtkPolyDataMapper cutterMapper = vtkPolyDataMapper.New();
             cutterMapper.SetInputConnection(cutter.GetOutputPort());
             cutterMapper.ScalarVisibilityOff();

             // Create plane actor
             vtkActor planeActor = vtkActor.New();
             planeActor.GetProperty().SetColor(1.0, 0.0, 0.0);
             planeActor.GetProperty().SetLineWidth(3);
             planeActor.SetMapper(cutterMapper);

             // Create input actor
             vtkActor inputActor = vtkActor.New();
             inputActor.GetProperty().SetColor(1.0, 0.8941, 0.7686); // bisque
             inputActor.SetMapper(inputMapper);

             // get a reference to the renderwindow of our renderWindowControl1
             vtkRenderWindow renderWindow = renderWindowControl1.RenderWindow;
             // renderer
             vtkRenderer renderer = renderWindow.GetRenderers().GetFirstRenderer();
             // set background color
             renderer.SetBackground(.2, .3, .4);
             renderer.AddActor(inputActor);
             renderer.AddActor(planeActor); //display the contour lines
          }
       }
    }