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Surface Trim Operation

Surface Trim means clipping an object with surface of another. The operation is similar to IBoolSection.Subtract, but leaves the resulting surface open. Only parts of the original surface which lies inside of the clipper objects (for open objects on the negative side which is opposite to direction of normals) are included into the result

In this version clipping only works for infinite prizms built on polygons used as clipper object

To trim a surface via Direct User Access rigt-click into KernelCAD window. In the context menu select Advanced > Edit > Clip (Shortcut: t key). Click a sequnce of points with the last one either Ctrl or Ctrl+Shift being held to define a polygon (details). Press x key to complete the operation

When the defined polygon is open the end lines assumed to be extended into infinity (rays)

The surface which if on the left side of the polygon will remain in the surface. This also means that for clockwise oriented polygons the area outside will remain, so this is a way for cutting holes in the surface

To perform this operation programmatically:

• Use IDIObjGenerator.Create(EObjectType.eObjTypePrizmInfinite) to create a prizm
• Query/cast the returned interface to IPrizmInfinite_KC
• Obtain IStrip implemented by the base polygon via query: IPrizmInfinite_KC.GetBase()>IStrip
• Query IStrip > IStripTopol. Use methods of IStripTopol to add points or otherwise modify structure of the polygon
• Use methods of IStrip to modify coordinates of corners via: IStrip.GetElement(index, false)>IElement>IElement.SetParam(0,x); SetParam(1,y);
• Use IPrizmInfinite_KC.GetFrame()>IFrame3 to modify position and orientation of the prizm in 3D space
• Query IBoolSectionEx from the ISection of the object to be trimmed
• Query IObjectOriented from the IPrizmInfinite_KC
• Call IBoolSectionEx.Clip() with the IObjectOriented as the first parameter

See also: Overlay Sample, Direct User Access, Cut Surface Operation