Object Array Sample
Source code for Object Array sample is available in Samples\VC
folder of the installation directory. It is recommended to
copy whole VC directory to location outside of the installation folder
before loading or compilation.
ObjArray is an MFC application, which demonstrates dynamic creation of objects.
See also C# Object Array sample
Visual Basic .NET Object Array sample
Visual C++ 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 dialogue. 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.
"Switch to parent" button on the top of the dialogue 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 modifying 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
CObjArrayDlg::OnButtAdd() and CObjArrayDlg::OnButtDelete() handlers.
New objects are added in CObjArrayDlg::OnButtAdd() handler. Depending on
selection in Type radio button group either NewStandardObjectDlg or
NewGenericObjectDlg is displayed. NewStandardObjectDlg uses
IStdShape interface to create new
objects. NewGenericObjectDlg uses Object
Generators to demonstrate more flexible but more complex object creation.
NewGenericObjectDlg::Create3DS() uses call to CoGetClassObject() COM API to get
access to class factory of Sect3DGenerator objects using its class id
CLSID_Sect3DGenerator. CLSID_Sect3DGenerator is declared in DIInterface.h common
header file.
Sect3DGenerator is a generic constructor of new 3D entity objects. It has a single interface I3DSectionGenerator, which is
obtained during the object creation with the help of call to CreateInstance()
method of the class factory. 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.
Function NewGenericObjectDlg::CreateSOR() 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.
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