#!F-adobe-helvetica-medium-r-normal--18* #!N #!CDarkGreen #!N #!Rpickin Using Pick #!N #!EC #!N #!N Picking consists of choosing a location on an object in an image using the mouse. A chosen location is called a "poke." Each poke may intersect the object in the image in one or more places (the intersections are called "picks") or may not intersect the object at all. For example, a poke on a spherical isosurface results in two "picks": one on the front of the sphere and one on the back. Picking differs from using probes, in which probes may be present anywhere in a 3-dimensional space, while picks always exist on the surface of an object. #!N #!N After you execute a visual program and have an image in the Image window, you can modify the visual program to include a #!F-adobe-times-bold-r-normal--18* Pick #!EF tool from the #!F-adobe-times-bold-r-normal--18* Special #!EF category. The Pick tool accepts input from the mouse and outputs a field that specifies the picked point or points. The "positions" component of this field identifies each picked point on the object in the image. The field can be used, for example, to identify all picked points with a glyph, or to start streamlines at each picked point. In addition, the field output by the Pick tool can be used by a user-written module to perform a variety of operations on the object in the image (e.g., coloring each picked object a particular color). IBM Visualization Data Explorer Programmer's Reference includes a sample module that uses the pick structure in this way. #!N #!N To use picking to select points on objects: #!N #!I0 #!N #!F-adobe-times-medium-r-normal--18* #!N #!N #!I30 #!N 1. Execute a visual program to produce an image in the Image window. #!N #!I30 #!N 2. In the VPE, place one or more pick tools from the #!F-adobe-times-bold-r-normal--18* Special #!EF category in the visual program, connecting them to the tools for which you want to provide input. #!N #!N The pick icons are numbered as you place them on the canvas. For example, the first pick icon you place is labeled "Pick_1," the second "Pick_2," and so on. You can change the label of the icon by using its Configuration dialog box. #!N #!I30 #!N 3. In the #!F-adobe-times-bold-r-normal--18* View Control... #!EF dialog box, select #!F-adobe-times-bold-r-normal--18* Pick #!EF mode from the #!F-adobe-times-bold-r-normal--18* Mode #!EF option box or use the #!F-adobe-times-bold-r-normal--18* Ctrl+I #!EF accelerator key. The dialog box changes to add the Pick controls. #!N #!N Select the pick tool you want by choosing the #!F-adobe-times-bold-r-normal--18* Pick(s) #!EF option box. This opens an options menu with a list of the available picks from which to select. #!N #!I30 #!N 4. Select a point or points as input to the tool connected to the Pick icon. #!N #!N To choose a point, click on a point in the image. A small square box appears, marking the point. #!N #!I0 #!N #!EF #!N Depending on whether you have the #!F-adobe-times-bold-r-normal--18* persistent #!EF parameter to the Pick tool set to 0 or 1, subsequent executions may or may not use the last pick point or points chosen. If #!F-adobe-times-bold-r-normal--18* persistent #!EF is set to 0, then pick points are not saved between executions; if #!F-adobe-times-bold-r-normal--18* persistent #!EF is set to 1, then pick points are saved between executions. Note: You can also enable Pick mode by using the #!F-adobe-times-bold-r-normal--18* intrctnMode #!EF parameter to the Image tool (see Image in IBM Visualization Data Explorer User's Reference). #!N #!N #!N #!F-adobe-times-medium-i-normal--18* Next Topic #!EF #!N #!N #!Lall322,dxall323 h Undo, Redo, and Reset #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
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