[vtkusers] Coordinates on a surface

[Dean Inglis]

Hi James,

I actually created a widget that I call vtkPropTracerWidget
that does essentially what you want.  It uses an internal vtkPropPicker:

<snip - initialize>
  this->Prop = NULL;
  this->PropPicker = vtkPropPicker::New();
  this->PropPicker->PickFromListOn();
<snip>

in your case, you would set this->Prop to your mesh and add the prop to
the picker:

<snip>
  this->PropPicker->InitializePickList();
  this->PropPicker->AddPickList(this->Prop);
<snip>

> also try to do it dynamically as the mouse moves across the window using a
>tkCellPicker that I instantiate as part of my vtkMFCView derived CView:

this is probably the way to go.  Your problem with the y-coord can be easily
resolved be getting the display window height in pixels, say DWH, and
setting

                       wx = float(LOWORD(lParam));
                       wy = DWH - float(HIWORD(lParam)) + 1.0f;


/* now add in some more vtk stuff... */

  if( !this->PropPicker->PickProp(wx,wy,Renderer) ){ return; }
  if( this->Prop !=  this->PropPicker->GetProp() ){ return; }

  float pos[3];
  this->PropPicker->GetPickPosition(pos);

/* use pos to query the data however you see fit ... */


Dean