```Date: Dec 8, 2012 1:28 AM
Author: Bob Hanlon
Subject: Re: Interactively placing points onto 3D surfaces

A clicking on a point on a 3D graphic would represent an infinitenumber of points on the line extending straight back into the 3Dspace.One approach would be use intersecting orthogonal lines to designate apoint. You could rotate the 3D graphic as you adjusted the linelocations to help identify the specific point of interest.Manipulate[ Column[{Show[    ParametricPlot3D[     {Cos[u], Sin[u] + Cos[v], Sin[v]},     {u, 0, 2 \[Pi]}, {v, -\[Pi], \[Pi]},     PlotStyle -> Opacity[.5]],    Graphics3D[{Thick,      Red, Line[{{-1, y, z}, {1, y, z}}],      Blue, Line[{{x, -2, z}, {x, 2, z}}],      Green, Line[{{x, y, -1}, {x, y, 1}}]}]],   StringForm["Point coordinates: ``",    Dynamic[pt = {x, y, z}]]}], {{x, 0, "x (red fixed)"}, -1, 1, Appearance -> "Labeled"}, {{y, 0, "y (blue fixed)"}, -2, 2, Appearance -> "Labeled"}, {{z, 0, "z (green fixed)"}, -1, 1, Appearance -> "Labeled"}]Dynamic[pt]Bob HanlonOn Fri, Dec 7, 2012 at 1:37 AM,  <wearer35429@mypacks.net> wrote:> Howdy folks.>> Could someone please help smash thru my current brick wall?>> I generate 3D surfaces from medical anatomy files (".off" files). I would like to be able to scroll the mouse over the surface & click to set an interactive point on the surface, & have the program be able to read the {x,y, z} coordinates of the new point.>> Can anyone point me in the right direction.>> Thanks very much.>> Tom>
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