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Programming of the KernelCAD Control

Manipulation of the current model and its rendering properties is performed via interfaces implemented by KernelCAD control. Interface is a simple notion, which does not require any special knowledge. Interface is a small group of methods (functions) related to a certain functionality. Programming Samples provide ample examples of their usage.

KernelCAD interfaces are organized in a hierarchical fashion. This means that one have to traverse the interface hierarchy tree using casts and other methods to obtain needed interface of a particular object.  IModel is the root interface for geometry-related interfaces, from which all its dependent interfaces can be obtained. To get IModel interface call GetModel method of the control which in C++ case will look like:

IModel * pIModel= (IModel*)m_ctrlCAD.GetModel();

Using casts (or QueryInterface() calls in C++) and other interface methods like IModel::GetSection() interface hierarchy can be traversed to obtain the interface needed and call its methods.

IView interface is the root for functionality related to viewing properties of the control's display rather than geometry of the model. IView reference is returned by GetView() method of the control. 

In unmanaged environments like native C++ or VB, every interface reference, obtained with the QueryInterface() or a call to an interface method, should be released with a call to Release() method, like pIModel->Release(), when it is no longer needed. In Visual Basic this operation looks like: 

Set iMyInterface = Nothing.

C++ interface declarations are available in DIInterface.h located in Samples\Vc\Include directory of the installation folder. The same folder contains DIError.h with declarations of error codes specific to DInsight software. All other return codes for interface methods are contained in Winerror.h - the standard header file of your development environment. If you cannot find one on your machine use copy from Samples\Vc\Include directory of this product installation folder. 

Microsoft Visual Basic and Microsoft Visual Studio .NET detect control's interfaces and types automatically after the control has been added to the project. To access this information open Object Browser and activate KernelCADTypeLib set.

Advanced: KernelCAD software slightly deviates from the COM standard. Traversing the Interface Hierarchy can obtain interface implemented by an object different from the original one. This means that result of a query depends on the query path. For example for a Generic 3D Object  path ISection-> IArray returns IArray of its child sections, but path ISection->IAxiBase->IArray returns IArray of its base knots. See also Interface queries

See also: User Input Validation