When straight lines and curves are created on a CAD system it is extremely unlikely that they are immediately of the correct form. The user has to ensure that the various parts of the geometry fit together correctly. Sometimes he will be including entities merely for constructional purposes as one would on a conventional drawing board. For example, it may be required to blend two circular arcs together to form a new curve. The final form cannot be specified immediately. It is necessary to construct both arcs in full, find where their intersection is and then trim away the parts that are not required. On a drawing board the intersection is found by eye (and the trimming performed with an eraser). To be able to do the same thing on a CAD system requires the presence of commands that find the intersection of specified geometric entities. The trimming is easily accomplished by redefining an end of each entity to be the calculated point of intersection and then removing the unwanted parts from the display (possibly by redrawing it).
KeywordsLine Segment Intersection Point Tool Path Outer Boundary Closed Curve
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