#!F-adobe-helvetica-medium-r-normal--18*
#!N 
#!N  #!Rpick Pick #!N #!N Category #!N #!N  #!Lcatspe,dxall761 h Special  #!EL  #!N 
#!N Function #!N #!N Outputs a pick structure. #!N #!N Syntax 
#!N #!N #!CForestGreen #!N  #!F-adobe-courier-bold-r-normal--18*   #!N  #!F-adobe-times-bold-r-normal--18*   picked #!EF = Pick( 
 #!F-adobe-times-bold-r-normal--18*   pickname, imagename, locations, reexecute, first, #!N persistent, interpolate, object, camera 
#!EF ); #!EF #!N #!N #!EC #!N #!N Inputs #!T,1,91,276,461,646  #!F-adobe-times-medium-r-normal--14*   
 #!F-adobe-times-bold-r-normal--18*   #!N TAB Name TAB Type TAB Default TAB Description #!EF 
#!N TAB pickname TAB string TAB none TAB name of cached 
picks #!N TAB imagename TAB string TAB none TAB name of 
cached scene #!N TAB locations TAB vectorlist TAB no default TAB 
2-D screen coordinate pick #!N TAB - TAB - TAB - 
TAB positions #!N TAB reexecute TAB flag TAB none TAB cause 
reexecution whenever pick #!N TAB - TAB - TAB - TAB 
list is reset #!N TAB first TAB flag TAB 1 TAB 
0: include all "picks" #!N TAB - TAB - TAB - 
TAB 1: include only first "picks" #!N TAB persistent TAB flag 
TAB 1 TAB 0: "picks" not saved #!N TAB - TAB 
- TAB - TAB 1: "picks" saved #!N TAB interpolate TAB 
integer TAB 0 TAB 0: no data interpolation #!N TAB - 
TAB - TAB - TAB 1: nearest vertex interpolation 2: #!N 
TAB - TAB - TAB - TAB interpolate #!N TAB object 
TAB object TAB no default TAB object to be "poked" #!N 
TAB camera TAB camera TAB none TAB camera used to create 
scene picked #!N TAB - TAB - TAB - TAB in 
#!N TAB - TAB - TAB - TAB #!EF #!N #!N 
Outputs #!T,1,161,321,646  #!F-adobe-times-medium-r-normal--14*    #!F-adobe-times-bold-r-normal--18*   #!N TAB Name TAB Type TAB Description 
#!EF #!N TAB picked TAB field TAB pick structure #!N TAB 
- TAB - TAB #!EF #!N #!N Functional Details #!N #!N 
Picking involves using the mouse to determine information about an object 
rendered in an image. (If there is more than one image 
in the visual program, then the image which is assumed is 
the one from which picking was made active using the View 
Control dialog.) The user may select one or more points on 
the screen by positioning the mouse and pressing the left button; 
each such action is referred to as a "poke." Each poke 
may intersect the object at one or more places or may 
miss the object altogether. Each intersection is called a "pick." For 
example, a poke on a spherical isosurface will result in two 
picks, one on the front surface and one on the rear. 
#!N #!N Individual subobjects in a structured scene may be made 
unpickable by attaching an attribute named "pickable," with a value of 
0 (zero), to the root of the subobject, using the Options 
module. #!N #!N The information returned by Pick in  #!F-adobe-times-bold-r-normal--18*   picked 
#!EF includes the positions in the (xyz) world-coordinate system at which 
the picks occurred. These positions (contained in the "positions" component of 
 #!F-adobe-times-bold-r-normal--18*   picked #!EF ) may be used to determine the coordinates 
of points on objects, to start streamlines, or to label points 
on the surface (by using AutoGlyph appropriately). These kinds of operations 
can be done directly in a visual program, without writing a 
special module. #!N #!N In addition to the pick positions,  #!F-adobe-times-bold-r-normal--18*   
picked #!EF contains information identifying the individual elements of the object 
structure that was picked. This information can be used to select 
elements of the object structure at any level down to the 
connections element and vertex closest to the pick point. See IBM 
Visualization Data Explorer Programmer's Reference for an example module that uses 
the position information contained in the pick structure. #!N #!I0 #!N 
#!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   pickname #!EF #!EF #!I50 #!N is 
used only by the user interface and is not intended to 
be set by users. #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   imagename #!EF 
#!EF #!I50 #!N is used only by the user interface and 
is not intended to be set by users. #!N #!I0 #!N 
 #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   locations #!EF #!EF #!I50 #!N is a list of 
2 dimensional screen coordinates pixel positions identifying the picks. If you 
are using the Image tool, this parameter is set automatically for 
you by the user interface. If you are using SuperviseWindow and 
SuperviseState, then the  #!F-adobe-times-bold-r-normal--18*   events #!EF output of SuperviseState should be 
used to provide this input. #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   reexecute 
#!EF #!EF #!I50 #!N is used only by the user interface 
and is not intended to be set by users. #!N #!I0 
#!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   first #!EF #!EF #!I50 #!N specifies whether all 
picks generated by a poke intersecting an object are to be 
added to the pick structure or only the first pick (i.e., 
the pick closest to the viewpoint): #!N #!I0 #!N #!N #!I0 
#!N  #!F-adobe-times-bold-r-normal--18*   0 #!EF #!I50 #!N All picks are added to 
the output. #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*   1 #!EF #!I50 #!N Only 
the first pick is reported for each poke. #!I0 #!N #!N 
#!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   persistent #!EF #!EF #!I50 #!N specifies 
whether or not picks are saved between executions: #!N #!I0 #!N 
#!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*   0 #!EF #!I50 #!N Picks are not 
saved. #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*   1 #!EF #!I50 #!N Picks are 
saved and are deleted only when the user makes new pokes. 
Note: When new picks are made, the previous pick points are 
discarded. #!I0 #!N #!N #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   interpolate #!EF 
#!EF #!I50 #!N specifies whether a "data" component should be created 
in  #!F-adobe-times-bold-r-normal--18*   picked #!EF and, if so, how the interpolation of 
values for that component should be performed. #!N #!N If the 
 #!F-adobe-times-bold-r-normal--18*   interpolate #!EF parameter is set to 1 or 2, the 
Pick output object will contain a set of components matching the 
set of dependent components in the picked object. Each of the 
components in the output object is dependent on the "positions" component 
of  #!F-adobe-times-bold-r-normal--18*   picked #!EF . For components that are dependent on 
connections in the picked object, the data for the picked element 
will be placed in the output component. #!N #!N For components 
that are dependent on positions in the picked object, the data 
placed in the output object is determined by one of two 
options: #!N #!I0 #!N #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-medium-r-normal--18*   1 = 
"nearest vertex" #!EF #!EF #!I50 #!N The data corresponding to the 
vertex nearest the pick point is extracted. #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*   
 #!F-adobe-times-medium-r-normal--18*   2 = "interpolated data" #!EF #!EF #!I50 #!N The data 
is interpolated from the vertex data of the picked element. #!I0 
#!N #!N In either case, an additional component is created (called 
"closest vertex") that receives the coordinates of the vertex closest to 
the pick point among the vertices of the picked element. Note: 
Regardless of which of the two options is selected, if different 
picks result in different sets of components or different data types 
in components of the same name, an error results. #!N #!I0 
#!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   object #!EF #!EF #!I50 #!N allows the user 
to override the object being picked. By default, this object is 
the one rendered in the Image window associated with the previous 
execution of the graph. If the scene consists of several objects 
collected before rendering, and if only some of them are to 
be made pickable, the user can pass those objects directly into 
Pick. The  #!F-adobe-times-bold-r-normal--18*   object #!EF parameter also makes it possible to 
pick in an object that lies in the same coordinate space 
as the scene does but is not in fact a part 
of the scene. #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   camera #!EF #!EF 
#!I50 #!N sets the camera used to create the scene being 
picked in. If you are using the Image tool, this parameter 
is set automatically for you by the user interface. If you 
are using SuperviseState and SuperviseWindow, then you must provide the camera 
used to render the scene. #!I0 #!N #!N Note: Pick currently 
supports surfaces, lines, and points. Picking does not support volume elements; 
if a poke is made on a volume object in the 
image, no picks will result. #!N #!N Example Visual Program #!CForestGreen 
#!N #!N  #!F-adobe-courier-bold-r-normal--18*   #!N PickStreamline.net #!EF #!N #!N #!EC #!N #!N 
See Also #!N #!N  #!Lsupwind,dxall961 h SuperviseWindow  #!EL  ,  #!Lsupstat,dxall958 h SuperviseState  #!EL  #!N #!N  #!Lpickin,dxall322 h Using Pick  #!EL  in 
IBM Visualization Data Explorer User's Guide. #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   Next 
Topic #!EF #!N #!N  #!Lplot,dxall904 h Plot  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N 
