[vtkusers] locate a vtkActor2D ???

[Cyril Giraudon]

Hello vtk-users,

I suppose it's a largely known problem but i haven't found the solution
anywhere.


/////////////////////
// Suppose you have :
/////////////////////

X[1:m], Y[1:n] two vectors.
X takes values from XMIN to XMAX with the step XSTEP.
Y takes values from YMIN to YMAX with the step YSTEP.
Z[1:m;1:n] a matrix defined by Z=f(X,Y).
ZMAX is the maximum value of Z.
ZMIN is the minimum value of Z.

I 'd like to draw a surface which represent Z.
The problem is the following :
if X and Y are contained in [0,1] all is OK,
otherwise I can see only Z where X and Z are
contained in [0,1].


Have I to normalize and translate X and Y ?
Or Is there a classical solution I haven't try (customize Coordinate
System for example ...) ?

Thanks a lot.

Cyril.


------------------------------------------------------------------
Here is the java code.

Java (1.4.2).
VTK 4.2.
------------------------------------------------------------------

public class Surface extends JComponent implements VtkPanelContainer 
{

  private vtkPanel renWin;

  public Surface(float[] X, float[]Y, float[][]Z) 
  {
    // Computation of :
    // XMIN, XMAX, XSTEP
    // YMIN, YMAX, YSTEP
    // ZMIN, ZMAX

    /////////////////////////////
    // You create a vtkPolydata :
    /////////////////////////////
    vtkFloatArray XYpoints = new vtkFloatArray();
    vtkFloatArray Zvalues = new vtkFloatArray();

    XYpoints.SetNumberOfComponents(3);
    XYpoints.SetNumberOfTuples(m*n);
    
    int n = 0;
    float x, y, z;
    for(int i=0;i<m;i++)
    {
      x = X[i]
      for(int j=0;j<n;j++)
      {
        y = Y[j];
        XYpoints.SetTuple3(n, x, y, 0);
        Zvalues.InsertValue(n, z);
        n++; 
      }
    }

    vtkCellArray mesh = new vtkCellArray();
    for(int i=0;i<m-1;i++)
    {
      for(int j=0;j<Datasize-1;j++)
      {
        mesh.InsertNextCell(4);
        mesh.InsertCellPoint((0+j)+m*i);
        mesh.InsertCellPoint((n+j)+m*i);
        mesh.InsertCellPoint((n+1+j)+m*i);
        mesh.InsertCellPoint((1+j)+m*i);
      }
    }
///////////////////////////////////////////////////
// I think I should use vtkStructuredGrid but it's
// for a course needs.
///////////////////////////////////////////////////

    vtkPoints points = new vtkPoints();
    points.SetData(XYpoints);

    vtkPolyData polydata = new vtkPolyData();
    polydata.SetPoints(points);
    polydata.SetPolys(mesh);
    polydata.GetPointData().SetScalars(Zvalues);

///////////////////////////////////////
// Now we build the data representation
///////////////////////////////////////

    vtkCoordinate coo = new vtkCoordinate();
    coo.SetCoordinateSystemToNormalizedViewport();

    vtkPolyDataMapper2D contMapper = new vtkPolyDataMapper2D();
    contMapper.SetTransformCoordinate(coo);
    contMapper.SetInput(polydata);
    contMapper.ScalarVisibilityOn();
    contMapper.SetScalarRange(ZMIN, ZMAX);

    vtkLookupTable mycolors  = new vtkLookupTable();
    mycolors.SetTableRange(ZMIN, ZMAX);
    contMapper.SetLookupTable(mycolors);
    

    vtkActor2D contActor = new vtkActor2D();
    contActor.SetMapper(contMapper);

    renWin.GetRenderer().SetBackground(1., 1., 1.);
    renWin.GetRenderer().AddActor(contActor);

    setLayout(new BorderLayout());
    add(renWin, BorderLayout.CENTER);

  public vtkPanel getRenWin() 
  {
    return renWin;
  }

  public static void main(String s[]) 
  {
    Surface panel = new Surface();
    JFrame frame = new JFrame("Contours2D");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add("Center", panel);
    frame.pack();
    frame.setVisible(true);
  }
}


-- 
Cyril Giraudon <giraudon at ifrance.com>