DG Kernel (ActiveX) Documentation


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Metrics C++ Sample

Metrics C++ sample demonstrates calculation of distances, and nearest points between two objects and usage of IMetrics2.Dist method. The sample is a simplified version of Metrics2 sample.

See also All samples, Collision detection, Collision Sample

Running the application  

The application expects the model to have at least two top level objects. Names of the first and the second objects are displayed on the right hand side of the form. The Calculate button calculates distances between the two objects and displays the result in 3D view.

By default pairs of nearest points are rendered connected with a red segment in 3D view. Check boxes in the Display group allow to turning on and off rendering shortest distances, nearest points and normals.

The Move Object control group allows changing position and orientation of either of the two objects. The movement is performed relative to the current location and orientation of the local frame of the object. Show check box displays or hides the local frame.

The "Is Closer Than" controls allow to determine whether the objects are closer than the distance specified in the edit box.

File menu allows loading new and saving the current model.

Implementation

All DG Kernel related functionality is implemented inside the MetricsDlg 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 for the first two top level objects of the model with the help of IModel.GetEntity and stored in m_iEntityFrom and m_iEntityTo member variables.

In MetricsDlg::InitModelInfo() called on start of the application IMetrics2 interfaces are queried from relevant ISection

Calculation of distance is performed in OnCalculate() handler, where and IMetrics2.Dist is called.

In this application the calculated nearest points are displayed in 3D view with line segments and points.

The application uses ClientDraw event, requested in OnInitDialog(), to add custom drawing of shortest segments and other elements to the scene. The drawing is performed inside OnClientDraw handler. In the OnClientDraw method the coordinates of each vertex are obtained via IVertex.GetVertexCoord. When rendering of normals, is requested they are obtained with a IVertex.GetNormal call in DrawNormals().

Work related to the "Is Closer than" group of controls is done in OnCalculateCloserThan handler with the help of IMetrics.IsCloserThan method.

Note that movements of the current object are performed in OnMoveObject via IFrame2 rather than IFrame to make movements relative to the current axes.