DGKC Control Documentation


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Free Form Curves

Free-form curves are defined by arrays of 3D points called Data Points or Data Array. To be continuous the curve is interpolated between data points. Data points do not have to be spaced evenly. Two consecutive points in the array must be different.

InterpolationDegree is an important property of a free-form curve. It determines how curve points are calculated between data points. The greater is InterpolationDegree the smoother the curve appears. In calculation of internal point InterpolationDegree+1 points are taken into account, which means that the curve has to have at least InterpolationDegree+1 data points. By default, InterpolationDegree is 1, in which case the curve is approximated by straight segments between data points.

The software assumes that the curve is smooth. If the modelled curve has sharp angles it still can be approximated, but InterpolationDegree has to be set to 1. It is recommended to (nearly) duplicate the angle point by adding another point very close to it, but not coinciding.

Free-form curves can be accessed via the ICurveFreeForm_DG interface.

Free-form curves are Geometric Curves, hence they implement ICurve_DG interface..

When Closed property is set to true the Data Array is assumed to represent a closed curve (continuous loop).

To create a free-from curve:

1. Call to IObjectGenerator_DG.Create<ICurveFreeForm_DG>() to obtain ICurveFreeForm_DG.

2. Obtain IPointArray_DG of the data array with a call to ICurveFreeForm_DG.GetData

3. Use IPointArray_DG to define the point array.

4. Select or tune in value for the InterpolationDegree property most appropriate for the application.

Performance note: Higher degree of interpolation makes relevant calculations little slower, but allow using fewer data points, which can actually result in better performance. It is recommended to make few experiments to find appropriate settings.

See also: Curves Overview, Native Curves