[vtkusers] (no subject)

[Amy Henderson]

vtkPointPicker should work, assuming you are trying to retrieve point 
data.  Use the Pick method to pick a point on the surface.  The first 2 
parameters (x and y) are the x and y pixel coordinates.  The z parameter 
should be set to 0.  The 4th parameter is the renderer you are using.  If 
you get a non-zero back from Pick (meaning that a point was successfully 
picked), call GetPointId, which returns the point id of the picked 
point.  You can use that information to get the scalar value associated 
with that point:

[[dataSet GetPointData] GetScalars] GetScalar $i

(where i is the value you got from GetPointId).

You may also need to specify the tolerance in the picker to determine how 
close you have to be to a point in the data set for it to be considered 
"picked".

- Amy

At 01:17 PM 11/1/2001 +0000, vtk_project at bonusfive.com wrote:
>Hi.  We're trying to retrieve points on polygon data
>based on the position of the mouse pointer, and then
>trying to return the scalar value associated with that
>point (all in tcl).  So far, we've tried using a
>vtkStyleInteractorUser which is giving what seems to be
>just the x and y position in the window, not relevant
>to the data.  We thought that maybe using the GetZ?
>function would yield coordinates we could use to
>retrieve the scalar values, but we can't get GetZ
>working.  Is this a situation where point picking is
>used?  If so, how is that done?  And how do we isolate
>scalar values based on point?  Thank you for any help
>you can give.  (Background note: This is a student
>project at UMBC on haptic display of surface certainty;
>the scalar values will be used by a Phantom device to
>give haptic feedback based on the user's pointing
>position)
>
>-Andy Grossman and Kirk
>Petri
>
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