function?callbackClickA3DPoint（src?eventData?pointCloud）
%?CALLBACKCLICK3DPOINT?mouse?click?callback?function?for?CLICKA3DPOINT
%
%???The?transformation?between?the?viewing?frame?and?the?point?cloud?frame
%???is?calculated?using?the?camera?viewing?direction?and?the?‘up‘?vector.
%???Then?the?point?cloud?is?transformed?into?the?viewing?frame.?Finally
%???the?z?coordinate?in?this?frame?is?ignored?and?the?x?and?y?coordinates
%???of?all?the?points?are?compared?with?the?mouse?click?location?and?the?
%???closest?point?is?selected.
%
%???Babak?Taati?-?May?4?2005
%???revised?Oct?31?2007
%???revised?Jun?3?2008
%???revised?May?19?2009

point?=?get（gca?‘CurrentPoint‘）;?%?mouse?click?position
camPos?=?get（gca?‘CameraPosition‘）;?%?camera?position
camTgt?=?get（gca?‘CameraTarget‘）;?%?where?the?camera?is?pointing?to

camDir?=?camPos?-?camTgt;?%?camera?direction
camUpVect?=?get（gca?‘CameraUpVector‘）;?%?camera?‘up‘?vector

%?build?an?orthonormal?frame?based?on?the?viewing?direction?and?the?
%?up?vector?（the?“view?frame“）
zAxis?=?camDir/norm（camDir）;????
upAxis?=?camUpVect/norm（camUpVect）;?
xAxis?=?cross（upAxis?zAxis）;
yAxis?=?cross（zAxis?xAxis）;

rot?=?[xAxis;?yAxis;?zAxis];?%?view?rotation?

%?the?point?cloud?represented?in?the?view?frame
rotatedPointCloud?=?rot?*?pointCloud;?

%?the?clicked?point?represented?in?the?view?frame
rotatedPointFront?=?rot?*?point‘?;

%?find?the?nearest?neighbour?to?the?clicked?point?
pointCloudIndex?=?dsearchn（rotatedPointCloud（1:2:）‘?...?
????rotatedPointFront（1:2））;

h?=?findobj（gca‘Tag‘‘pt‘）;?%?try?to?find?the?old?point
selectedPoint?=?pointCloud（:?pointCloudIndex）;?

if?isempty（h）?%?if?it‘s?the?first?click?（i.e.?no?previous?point?to?delete）
????
????%?highlight?the?selected?point
????h?=?plot3（selectedPoint（1:）?selectedPoint（2:）?...
????????selectedPoint（3:）?‘r.‘?‘MarkerSize‘?20）;?
????set（h‘Tag‘‘pt‘）;?%?set?its?Tag?property?for?later?use???

else?%?if?it?is?not?the?first?click

????delete（h）;?%?delete?the?previously?selected?point
????
????%?highlight?the?newly?selected?point
????h?=?plot3（selectedPoint（1:）?selectedPoint（2:）?...
????????selectedPoint（3:）?‘r.‘?‘MarkerSize‘?20）;??
????set（h‘Tag‘‘pt‘）;??%?set?its?Tag?property?for?later?use

end

fprintf（‘you?clicked?on?point?number?%d\n‘?pointCloudIndex）;