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Pick Visual C++ Sample

Pick is an application, which displays Light.glm model. It demonstrates programming and handling selection of  objects in 3D view by the end user.

Overview

Implementation

On load of the form the default (View) mode of the component is changed to Modify in Form_Load Sub by using IViewModal interface obtained via IView interface.

KernelCAD1_CurrentObjectChanged handler of the CurrentObjectChanged event obtains ISection interface of the selected object by converting the parameter supplied in the handler, obtains name of the object using ISection.GetName and displays it on the form. Note the 

Both methods two and three use Function GetObjNameAt, which calls ILookEx.GetItemAt method to obtain IItem interface implemented by the object beneath the window point. the Obtained interface is used to query an ISection, which returns name of the object via GetName.

Note the RequestClientDraw call, which enables ClientDraw event. This allows the cross-hair to be drawn in the KernelCAD1_ClientDraw handler.

For the third method MouseHover event is enabled/disabled in CheckHover_Click() with a call to RequestEvent (eEventMouseHover). Handler KernelCAD1_MouseEx of the event uses coordinates of the cursor supplied via parameters of the event to call the GetObjNameAt method. Note that it would be wrong to place this code into Mouse Move event handler as detection adds extra load on rendering and can cause flickering.

Coordinates of the selected 3D point are calculated in GetObjNameAt Sub with the help of IPick.GetItemAt3D or IPick.GetItemAtDepth If the local coordinates are required, global coordinates returned by IPick.GetItemAt3D are converted to local ones relative to the selected object with the help of IFrameEx queried from the obtained IItem. For case of View Frame the 3D point is calculated via  ILookEx.ScreenTo3DEx.

See also IPick, ILookEx, IItem,, All samples.