Hi,<br>   The following is my C++ code converted from annotatePick.tcl. I know there are many bugs,expect you to correct them.<br>   Thanks again  <br><br><br>static void annotatePick(void *arg)  <br>{   vtkCellPicker *picker=vtkCellPicker::New();<br>    vtkTextMapper *textMapper=vtkTextMapper::New();<br>    vtkActor2D *textActor=vtkActor2D::New();<br>    vtkRenderWindow *renWin=vtkRenderWindow::New();<br><br>    if (picker-&gt;GetCellId()&lt; 0 ) <br>        {<br>                textActor-&gt;VisibilityOff();<br>                <br>    } else <br>        {<br>                float *selPt; <br>                float *pickpos;<br>                int xp,yp,zp;<br>                int X,Y;<br>                <br>                selPt=picker-&gt;GetSelectionPoint();   <br>        cout&lt;&lt;&quot;Screen location:&quot;&lt;&lt;selPt[0]&lt;&lt;&quot; &quot;&lt;&lt;selPt[1]&lt;&lt;&quot;\n&quot;;<br>                X=selPt[0];<br>                Y=selPt[1];<br>                pickpos = picker-&gt;GetPickPosition();  <br>                cout&lt;&lt;&quot;Point location:&quot;&lt;&lt;pickpos[0]&lt;&lt;&quot; &quot;&lt;&lt;pickpos[1]&lt;&lt;&quot; &quot;&lt;&lt;pickpos[2]&lt;&lt;&quot;\n&quot;;<br>                xp=pickpos[0];<br>                yp=pickpos[1];<br>                zp=pickpos[2];<br>                <br>                textMapper-&gt;SetInput(&quot;($xp, $yp, $zp)&quot;);<br>                textActor-&gt;SetPosition(X,Y);<br>                textActor-&gt;VisibilityOn();<br>        }<br>        <br>        renWin-&gt;Render();<br>}<br><br><br>int main(int argc, char* argv[])<br>{   vtkSphereSource *sphere=vtkSphereSource::New();<br><br>vtkPolyDataMapper *sphereMapper=vtkPolyDataMapper::New();<br>sphereMapper-&gt;SetInput(sphere-&gt;GetOutput());<br>sphereMapper-&gt;GlobalImmediateModeRenderingOn();<br>vtkLODActor *sphereActor=vtkLODActor::New();<br>sphereActor-&gt;SetMapper(sphereMapper);<br><br>vtkConeSource *cone=vtkConeSource::New();<br>vtkGlyph3D *glyph=vtkGlyph3D::New();<br>glyph-&gt;SetInput(sphere-&gt;GetOutput());<br>glyph-&gt;SetSource(cone-&gt;GetOutput());<br>glyph-&gt;SetVectorModeToUseNormal();<br>glyph-&gt;SetScaleModeToScaleByVector();<br>glyph-&gt;SetScaleFactor(0.25);<br>vtkPolyDataMapper *spikeMapper=vtkPolyDataMapper::New();<br>spikeMapper-&gt;SetInput(glyph-&gt;GetOutput());<br>vtkLODActor *spikeActor=vtkLODActor::New();<br>spikeActor-&gt;SetMapper(spikeMapper);<br><br>vtkCellPicker *picker=vtkCellPicker::New();<br>//picker-&gt;AddObserver(vtkCommand::EndPickEvent,annotatePick);<br><br>vtkTextMapper *textMapper=vtkTextMapper::New();<br><br><br>vtkActor2D *textActor=vtkActor2D::New();<br>textActor-&gt;VisibilityOff();<br>textActor-&gt;SetMapper(textMapper);<br><br>vtkRenderer *ren1=vtkRenderer::New();<br>vtkRenderWindow *renWin=vtkRenderWindow::New();<br>renWin-&gt;AddRenderer(ren1);<br>vtkRenderWindowInteractor *iren=vtkRenderWindowInteractor::New();<br>iren-&gt;SetRenderWindow(renWin);<br>iren-&gt;SetPicker(picker);<br><br>ren1-&gt;AddActor2D(textActor);<br>ren1-&gt;AddActor(sphereActor);<br>ren1-&gt;AddActor(spikeActor);<br>ren1-&gt;SetBackground(1,1,1);<br>renWin-&gt;SetSize(300,300);<br><br>vtkCamera *cam1=vtkCamera::New();<br>cam1=ren1-&gt;GetActiveCamera();<br>cam1-&gt;Zoom(1.4);<br><br>//iren AddObserver UserEvent {wm deiconify .vtkInteract}<br><br>renWin-&gt;Render();<br>iren-&gt;Start();<br>iren-&gt;Initialize();<br>//picker-&gt;Pick(85,126,0,ren1);<br><br>        return 0;<br>}<br><font style='font-size:14.8px'> </font>
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