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Object Array Sample

Source code for Object Array sample is available in Samples\NET\VB folder of the installation directory. It is recommended to copy the folder to location outside of the installation folder before loading or compilation. ObjArray is an .NET Windows Forms application, which demonstrates dynamic creation of objects.

See also C# Object Array sample  C++ Object Array sample   All VB .NET Samples,   Visual Basic .NET Samples, All samples

Running the application  

Controls on the right allow navigation between objects in the currently loaded model. (see Structure of DInsight models). They represent a simplified version of Model Explorer of 3D Debugger.  Children group displays number of children in the current object and allows to make current one of them. The current object is highlighted in 3D with blue color and its name is displayed at the top of the dialog. On load "Children" group displays information about objects in the model, meaning that the whole model is considered as the top object in the hierarchy. 

"Delete" button deletes the child selected in the "Child" edit box.

"Switch to parent" button on the top of the dialog makes parent the current object.

"Position" edit boxes allow modification of location of the current object.

"New Child" group allows adding new objects to the model or new children to the current object. 

File submenu allows saving and loading models.

"Current Object" submenu contains operations with the model structure:

Operations

"Delete" command deletes the child selected in the "Child" edit box.

"Detach" command makes the current object independent top level object of the model. On this command nothing will change in the 3D view. To make sure that the command was carried out try to modify position of the current object using "Position" edit boxes. The object should move independently of its previous parent.

"Join" command makes the first top level object (different from the current) child of the current object. This command is invalid when a top object is being attached to its child. As the result the object will move together with its parent.

Implementation

The most important work specific to this sample is done using IArray interface. IArray is a topological interface, which means it changes structure of the model rather than changing its parameters. Actions performed by IArray depend on context. In this sample IArray adds or deletes child objects from/to the entity or model it was queried from. It is done in ButtonAdd_Click() and ButtonDelete_Click() methods of ObjArrayForm class. 

New objects are added in ButtonAdd_Click()  handler.  Depending on selection in Type radio button group either NewStandardObjectForm or NewGenericObjectForm is displayed. NewStandardObjectForm uses IStdShape interface to create new objects. NewGenericObjectForm uses Object Generators to demonstrate more flexible but more complex object creation.

NewGenericObjectForm.Create3DS() method creates new  Sect3DGeneratorClass object, which is a generic constructor of 3D entity objects. Sect3DGeneratorClass has a single interface I3DSectionGenerator, which is queried immediately from the object. Creation of the actual 3D Entity is done by using Create() method of I3DSectionGenerator. Create() returns an ISection interface, implemented by the new entity, which is used later to add to the array of objects of the model or parent entity. Prior to that, default parameters for the required entity are collected into a DI3DSectInfo structure by Set3DSDefaults() function.

Method NewGenericObjectForm.CreateSOR() of the form does the same job for Surface Of Revolution type of objects. All other generic objects are constructed with the help of  DIObjGenerator.

Suggested exercise

Add operation to change order of top level object in the model.