DG Kernel Documentation


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Patchwork Visual Basic .NET Sample

Description

Implementation

All DG Kernel related functionality is implemented inside the Patchwork form class. The DG Kernel related data is initialized inside InitModelInfo() method, which uses GetModel method of the DG Kernel control to obtain the root interface of the hierarchy. ISection interfaces, representing generic DG Kernel object, are obtained in UpdateObjectInfo() for the current object with the help of IModel.GetEntity. ISurface interface then queried from the ISection. and stored in m_iSurface member of the class.

m_iList array keeps three lists, namely lists of all vertices, edges and patches in the surface. Index of the element coincides with its dimension. These are obtained in UpdateObjectInfo() with calls to methods of ISurface.

UpdatePatchInfo() method is supposed to be called when the current patch has changed to update all related information. Elements stored in a list are interpreted by the Visual Studio as IntPtr type. The actual type of the element, as described by documentation is IPatch. This conversion is performed with a call to System.Runtime.InteropServices.Marshal.GetObjectForIUnknown(p) .NET method. The resulting IPatch reference is stored in m_iCurElem(2) member.

Array of edges in the patch are retrieved in the same UpdatePatchInfo() with a call to IPatch.GetEdges method and stored in m_iArrEdges member.

The m_iCurElem array, which declared as Object type stores IVertex, IKCLine and IPatch interfaces for the current element in the surface.

UpdateCurrentEdgeInfo() applies work similar to UpdatePatchInfo() to edges of the surface. m_bBrowseAll member indicates the current user selection: whether the next edge should be taken from the m_iList(1) list of all edges in the surface or from the array of the patch edges m_iArrEdges.

UpdateCurrentVertexInfo() does work similar to UpdateCurrentEdgeInfo() for vertices. The method also obtains coordinates of the vertex with a call to IVertex.GetVertexCoord() via GetPoint method of the Patchwork class and stores it in m_curVertex variable.

Current selection is highlighted in 3D by OnClientDraw handler of the ClientDraw event. The current patch is rendered using IGraphicItem interface stored in m_iGraphicItemPatch variable. IGraphicItem is queried from IPatch interface m_iCurElem(2). Note how the color of the patch was set with m_iDraw.Color(1.0, 1.0, 0.0, 1.0) prior the IGraphicItem.Draw call. The current edge and the current vertex are rendered by using appropriate methods of IDraw.