Hi Jerry,<br />
<p>do you want something like this?</p>
<div style="margin-left: 50px;"><img src="http://vtk.1045678.n5.nabble.com/file/n5714177/VTK_Examples_CSharp_vtkImageActor_With_Overlayed_Renderer.png" border="0"/77></div>
<p>I have written an example in C#. The basic idea is to overlay an additional renderer where the cross is displayed. Both renderers are synchronized.<br />
Whenever you click the image the cross will follow the new position.</p>
<pre><span style=' color: Blue;'>using</span> System;
<span style=' color: Blue;'>using</span> System.ComponentModel;
<span style=' color: Blue;'>using</span> System.Drawing;
<span style=' color: Blue;'>using</span> System.Windows.Forms;
<span style=' color: Blue;'>using</span> System.Diagnostics;
<span style=' color: Blue;'>using</span> Kitware.VTK;
<span style=' color: Blue;'>namespace</span> TestActiViz {
<span style=' color: Blue;'>public</span> <span style=' color: Blue;'>partial</span> <span style=' color: Blue;'>class</span> Form1 : Form {
vtkCamera _CameraOverlay;
vtkActor _Cross;
vtkPropPicker _PropPicker;
vtkRenderWindow _RenderWindow;
<span style=' color: Blue;'>public</span> Form1() {
InitializeComponent();
}
<span style=' color: Blue;'>protected</span> <span style=' color: Blue;'>override</span> <span style=' color: Blue;'>void</span> OnLoad(EventArgs e) {
<span style=' color: Blue;'>base</span>.OnLoad(e);
<span style=' color: Blue;'>try</span> {
TestImageActorOverlay();
}
<span style=' color: Blue;'>catch</span>(Exception ex) {
MessageBox.Show(<span style=' color: Maroon;'>"Exception: "</span> + ex.Message);
}
}
<span style=' color: Blue;'>private</span> <span style=' color: Blue;'>void</span> TestImageActorOverlay() {
<span style=' color: Green;'>// Path to vtk data must be set as an environment variable</span>
<span style=' color: Green;'>// VTK_DATA_ROOT = "C:\VTK\vtkdata-5.8.0"</span>
vtkTesting test = vtkTesting.New();
<span style=' color: Blue;'>string</span> root = test.GetDataRoot();
<span style=' color: Blue;'>string</span> filePath = System.IO.Path.Combine(root, <span style=' color: Maroon;'>@"Data\clouds.jpeg"</span>);
vtkJPEGReader reader = vtkJPEGReader.New();
<span style=' color: Blue;'>if</span>(reader.CanReadFile(filePath) == <span style=' color: Maroon;'>0</span>) {
MessageBox.Show(<span style=' color: Maroon;'>"Cannot read file \""</span> +
filePath +
<span style=' color: Maroon;'>"\""</span>, <span style=' color: Maroon;'>"Error"</span>, MessageBoxButtons.OK);
<span style=' color: Blue;'>return</span>;
}
reader.SetFileName(filePath);
reader.Update();
<span style=' color: Green;'>// we need the imagedata to get the world coordinates of the center,</span>
<span style=' color: Green;'>// get the bounds and get the scalar range</span>
vtkImageData imageData = reader.GetOutput();
<span style=' color: Green;'>// Create an imageActor</span>
vtkImageActor imageActor = vtkImageActor.New();
imageActor.SetInput(imageData);
<span style=' color: Green;'>// get bounds and center of the imagedata to size and position the _Cross</span>
<span style=' color: Blue;'>double</span>[] bounds = imageData.GetBounds();
SizeF imageSize = <span style=' color: Blue;'>new</span> SizeF(
(<span style=' color: Blue;'>float</span>)( bounds[<span style=' color: Maroon;'>1</span>] - bounds[<span style=' color: Maroon;'>0</span>] ),
(<span style=' color: Blue;'>float</span>)( bounds[<span style=' color: Maroon;'>3</span>] - bounds[<span style=' color: Maroon;'>2</span>] ));
<span style=' color: Blue;'>double</span>[] imageCenter = imageData.GetCenter();
<span style=' color: Blue;'>float</span> max = Math.Max(imageSize.Width, imageSize.Height);
vtkPolyDataMapper mapper = vtkPolyDataMapper.New();
mapper.SetInput(CreateCross(max / <span style=' color: Maroon;'>10</span>));
_Cross = vtkActor.New();
_Cross.GetProperty().SetLineWidth(<span style=' color: Maroon;'>5</span>);
_Cross.SetPosition(
imageCenter[<span style=' color: Maroon;'>0</span>],
imageCenter[<span style=' color: Maroon;'>1</span>],
imageCenter[<span style=' color: Maroon;'>2</span>]);
_Cross.SetMapper(mapper);
<span style=' color: Green;'>// get a reference to the renderwindow of our renderWindowControl1</span>
_RenderWindow = renderWindowControl1.RenderWindow;
<span style=' color: Green;'>// renderer</span>
vtkRenderer renderer = _RenderWindow.GetRenderers().GetFirstRenderer();
<span style=' color: Green;'>// set background color</span>
renderer.SetBackground(<span style=' color: Maroon;'>0</span><span style=' color: Maroon;'>.2</span>, <span style=' color: Maroon;'>0</span><span style=' color: Maroon;'>.3</span>, <span style=' color: Maroon;'>0</span><span style=' color: Maroon;'>.4</span>);
<span style=' color: Green;'>// add our imageActor to the renderer</span>
renderer.AddActor(imageActor);
<span style=' color: Green;'>// important call to make entire image visible</span>
renderer.ResetCamera();
<span style=' color: Green;'>// create an interactorstyle and event handler for pressing left mouse button</span>
vtkInteractorStyleImage interactorStyleImage = vtkInteractorStyleImage.New();
_RenderWindow.GetInteractor().SetInteractorStyle(interactorStyleImage);
interactorStyleImage.LeftButtonPressEvt +=
<span style=' color: Blue;'>new</span> vtkObject.vtkObjectEventHandler(InteractorStyleImage_LeftButtonPressEvt);
<span style=' color: Green;'>// create a transparent overlay renderer</span>
_RenderWindow.SetNumberOfLayers(<span style=' color: Maroon;'>2</span>);
vtkRenderer rendererOverlay = vtkRenderer.New();
rendererOverlay.SetLayer(<span style=' color: Maroon;'>1</span>);
<span style=' color: Green;'>// important, cause we want the renderer which contains </span>
<span style=' color: Green;'>// the imageActor to be interactive and not the overlay</span>
rendererOverlay.SetInteractive(<span style=' color: Maroon;'>0</span>);
_RenderWindow.AddRenderer(rendererOverlay);
rendererOverlay.AddActor(_Cross);
_CameraOverlay = rendererOverlay.GetActiveCamera();
<span style=' color: Green;'>// synchronize cameras</span>
_CameraOverlay.ShallowCopy(renderer.GetActiveCamera());
<span style=' color: Green;'>// event handler to synchronize cameras</span>
renderer.GetActiveCamera().ModifiedEvt +=
<span style=' color: Blue;'>new</span> vtkObject.vtkObjectEventHandler(Camera_ModifiedEvt);
_PropPicker = vtkPropPicker.New();
}
<span style=' color: Blue;'>void</span> InteractorStyleImage_LeftButtonPressEvt(vtkObject sender, vtkObjectEventArgs e) {
vtkInteractorStyleImage caller = e.Caller <span style=' color: Blue;'>as</span> vtkInteractorStyleImage;
<span style=' color: Blue;'>if</span>(caller != <span style=' color: Blue;'>null</span>) {
<span style=' color: Blue;'>int</span>[] mousePosition = caller.GetInteractor().GetLastEventPosition();
<span style=' color: Green;'>//Debug.WriteLine("left mouse button pressed -> mouse position: " </span>
<span style=' color: Green;'>// + mousePosition[0] </span>
<span style=' color: Green;'>// + " " </span>
<span style=' color: Green;'>// + mousePosition[1]);</span>
<span style=' color: Blue;'>int</span> ret = _PropPicker.Pick(
mousePosition[<span style=' color: Maroon;'>0</span>],
mousePosition[<span style=' color: Maroon;'>1</span>],
<span style=' color: Maroon;'>0</span>,
_RenderWindow.GetRenderers().GetFirstRenderer());
<span style=' color: Blue;'>if</span>(ret == <span style=' color: Maroon;'>1</span>) {
<span style=' color: Blue;'>double</span>[] pos = _Cross.GetPosition();
<span style=' color: Blue;'>double</span>[] pickPosition = _PropPicker.GetPickPosition();
<span style=' color: Green;'>//Debug.WriteLine("Pick Position: " </span>
<span style=' color: Green;'>// + pickPosition[0] + " " </span>
<span style=' color: Green;'>// + pickPosition[1] + " " </span>
<span style=' color: Green;'>// + pickPosition[2]);</span>
_Cross.SetPosition(
pickPosition[<span style=' color: Maroon;'>0</span>],
pickPosition[<span style=' color: Maroon;'>1</span>],
pickPosition[<span style=' color: Maroon;'>2</span>]);
_RenderWindow.Render();
}
}
}
<span style=' color: Blue;'>void</span> Camera_ModifiedEvt(vtkObject sender, vtkObjectEventArgs e) {
_CameraOverlay.ShallowCopy((vtkCamera)sender);
}
<span style=' color: Green;'>// create a cross</span>
vtkPolyData CreateCross(<span style=' color: Blue;'>float</span> size) {
<span style=' color: Green;'>// Create a vtkPoints object and store the points in it</span>
vtkPoints pts = vtkPoints.New();
pts.InsertNextPoint(-size / <span style=' color: Maroon;'>2</span>, <span style=' color: Maroon;'>0</span>, <span style=' color: Maroon;'>0</span>);
pts.InsertNextPoint(size / <span style=' color: Maroon;'>2</span>, <span style=' color: Maroon;'>0</span>, <span style=' color: Maroon;'>0</span>);
pts.InsertNextPoint(<span style=' color: Maroon;'>0</span>, -size / <span style=' color: Maroon;'>2</span>, <span style=' color: Maroon;'>0</span>);
pts.InsertNextPoint(<span style=' color: Maroon;'>0</span>, size / <span style=' color: Maroon;'>2</span>, <span style=' color: Maroon;'>0</span>);
<span style=' color: Green;'>// Setup the colors array</span>
<span style=' color: Blue;'>byte</span>[] color = <span style=' color: Blue;'>new</span> <span style=' color: Blue;'>byte</span>[] { <span style=' color: Maroon;'>255</span>, <span style=' color: Maroon;'>128</span>, <span style=' color: Maroon;'>0</span> };
vtkUnsignedCharArray colors = vtkUnsignedCharArray.New();
colors.SetNumberOfComponents(<span style=' color: Maroon;'>3</span>);
colors.SetName(<span style=' color: Maroon;'>"Colors"</span>);
<span style=' color: Green;'>// Add the colors we created to the colors array</span>
colors.InsertNextValue(color[<span style=' color: Maroon;'>0</span>]);
colors.InsertNextValue(color[<span style=' color: Maroon;'>1</span>]);
colors.InsertNextValue(color[<span style=' color: Maroon;'>2</span>]);
colors.InsertNextValue(color[<span style=' color: Maroon;'>0</span>]);
colors.InsertNextValue(color[<span style=' color: Maroon;'>1</span>]);
colors.InsertNextValue(color[<span style=' color: Maroon;'>2</span>]);
<span style=' color: Green;'>// Create the first line</span>
vtkLine line0 = vtkLine.New();
line0.GetPointIds().SetId(<span style=' color: Maroon;'>0</span>, <span style=' color: Maroon;'>0</span>);
line0.GetPointIds().SetId(<span style=' color: Maroon;'>1</span>, <span style=' color: Maroon;'>1</span>);
<span style=' color: Green;'>// Create the second line</span>
vtkLine line1 = vtkLine.New();
line1.GetPointIds().SetId(<span style=' color: Maroon;'>0</span>, <span style=' color: Maroon;'>2</span>);
line1.GetPointIds().SetId(<span style=' color: Maroon;'>1</span>, <span style=' color: Maroon;'>3</span>);
<span style=' color: Green;'>// Create a cell array to store the lines in and add the lines to it</span>
vtkCellArray lines = vtkCellArray.New();
lines.InsertNextCell(line0);
lines.InsertNextCell(line1);
<span style=' color: Green;'>// Create a polydata to store everything in</span>
vtkPolyData linesPolyData = vtkPolyData.New();
<span style=' color: Green;'>// Add the points to the dataset</span>
linesPolyData.SetPoints(pts);
<span style=' color: Green;'>// Add the lines to the dataset</span>
linesPolyData.SetLines(lines);
<span style=' color: Green;'>// Color the lines</span>
linesPolyData.GetCellData().SetScalars(colors);
<span style=' color: Blue;'>return</span> linesPolyData;
}
}
}
</pre><br />
Hope that's what your looking for.<br /><br />
with kind regards<br />
Jochen
<br/><hr align="left" width="300" />
View this message in context: <a href="http://vtk.1045678.n5.nabble.com/Draw-a-2D-cross-on-vtkImageActor-tp5714166p5714177.html">Re: Draw a 2D cross on vtkImageActor</a><br/>
Sent from the <a href="http://vtk.1045678.n5.nabble.com/VTK-Users-f1224199.html">VTK - Users mailing list archive</a> at Nabble.com.<br/>