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Patch Visual Basic Tutorial

Patch Tutorial demonstrates incorporation of DG Kernel Control into a simple Windows Form application using Microsoft Visual Studio.  Source code for Patch sample is available in Samples\NET\VB\Patch\ folder of the installation directory.

See also: Sample List

This tutorial assumes basic familiarity with Visual Studio. It is based on Visual Studio 2019.

The Application

Patch application creates a new truncated cone and allows modification of its parameters.

Step 1. Creating the project

• Open Visual Studio. Select File > New > Project in the menu. In the "Create a new project" make sure Visual Basic, Windows, Desktop are current on top. Select "Windows Forms App (.NET Framework) Visual Basic" project type. Click Next. Enter "Patch" for the project name. Select location and make sure .NET framework 4.5 is selected. Click Create.

• In Solution Explorer select the Form1.vb created by default and rename it (using context menu on right-mouse click) to Patch.vb. Accept the suggestion to rename related elements when asked.

Step 2. Inserting the DG Kernel Control

• Open Patch form in design mode and adjust size of the form to 890, 532 by pasting or typing the pair in Size property of the Properties Window (View > "Properties Window"). Change also Text property to "Patch".

• Expand the Components tab of the Toolbox (View > Toolbox). If DGKC control is not there, right click on the tab and select 'Choose Items...'. If DGKC is not listed in the .NET Framework Components tab, click the Browse button  and select DGKernel_7_1\Bin\AnyCPU\DGKC.dll in the DGK installation folder

• Select DGKC in the Toolbox and place the control on the left in the form. Save All. Close the from designer. A new member of type DGKC called Dgkc1 will be added to the Patch class.

• Open the form. Select the control and change its size to 698, 482 using Properties Window.

• Right-click on the control and select Properties. The form shows properties of the control. The properties can also be accessed via the Properties Window of Visual Studio. The main one, ModelPath, can point to an .mdg model file or a file in any other supported format. We will leave it empty as our entity will be created in the code.

• Open the Object Browser (View > Object Browser menu option). Expand DGKC and its child node. This node displays all necessary information about types, interfaces and their methods available in the component.

Step 3. Creating the Entity 

• To create handler for the Load event of the form, in design mode, click on the form outside the control. Click Events icon on the top of Properties Window. Select Load row in the list and double-click the row on the right. A new Patch_Load() method will be added to the Patch class.

• Add line:

  Imports DGKC

  at the top of the Patch.vb

• Next we will get access to IModel_DG  interface implemented by the control. Add to Patch_Load() the next line (without the (A) annotation):

  Dim iModel As IModel_DG = Dgkc1.GetModel()           (A)

• Add the following declarations to the Patch class:

  Dim m_iEntity As IEntity_DG
  Dim m_baseRadius As Double
  Dim m_topRadius As Double
  Dim m_height As Double

• Initialise the parameters in New() Patch constructor or on start of  Patch_Load() as:

  m_baseRadius = 10
  m_topRadius = 5
  m_height = 10

• Add the following three lines just below the line (A):

  Dim iStdShape As IStdShape_DG = iModel.Query(Of IStdShape_DG)()
  m_iEntity = iStdShape.Cylinder(m_baseRadius, m_topRadius, m_height)
  iModel.AddEntity(m_iEntity)

  The first line obtains an interface for creation of basic shapes. The second line creates a cylindrical object and stores its reference in m_iEntity. The third line adds the entity to the model to be displayed in the 3D view.

• Add the following two lines at the end of Patch_Load():

  Dim iView As IView_DG = Dgkc1.GetView()
  iView.Reset(True, True)

  The first line accesses IView_DG, which is the root of the view-related functionality and the second line refits the view to include the new object.

Step 4. Implementing Modifications of the Object.

• Add three edit boxes for the parameters and an Apply button to the form. Please make sure the text in edit boxes coincides with the initial values. The controls can be copied in design mode from the installed completed version of the sample

• In handler of the Apply button, add: 

  m_baseRadius = Double.Parse(editBaseRad.Text)
  m_topRadius = Double.Parse(editTopRad.Text)
  m_height = Double.Parse(editHeight.Text)

  Dim iModel As IModel_DG = Dgkc1.GetModel()
  Dim iStdShapeRef As IStdShapeRef_DG = iModel.Query(Of IStdShapeRef_DG)()
  iStdShapeRef.Cylinder(m_baseRadius, m_topRadius, m_height, m_iEntity)

  Dgkc1.UpdateView()

  Notice the different version of interface used. IStdShapeRef_DG is designed for modification (and creation) rather than creation only. The last line redraws the window.

• Run the application and test modifications of the entity.