Closed and open polygons

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Posts: 696
Joined: Sat Dec 03, 2011 9:19 pm
Location: Maine USA and Suffolk England

Closed and open polygons

Post by debenriver »

Maybe a bit specialist – but a complex curved shape (like the ring frame of a boat) can be converted to a polygon, often with many hundreds or even thousands of sides because of the complex nature of the curved shape. Then they can be saved as DXF files for CNC cutting.

RealCADD allows you to calculate the area of the polygon, and the centre of area (both of which are perfect for calculating the weight estimate and centres of gravity), and whether it is closed or open. For CNC cutting, the curve needs to be continuous – no gaps or overlaid lines etc. – that is basically "Closed".

What I'm wondering is, if when RealCADD says it's "Not closed", if it's feasible to indicate where the problem or problems lie. Knowing that there is a discontinuity of some sort is great, and allows one to deliver problem-free DXF files to the CNC facility. But with possibly thousands of very small lines making up the shape it can be very hard to discover where exactly there is a gap or an overlay.

Probably not main-stream enough to be important ..... or too hard to do?

Cheers -- George
Eric Pousse
Posts: 1064
Joined: Sat Dec 03, 2011 12:31 pm
Location: Tours - France

Re: Closed and open polygons

Post by Eric Pousse »

Bonjour George,

You can know there are this problems.
Select some lines, convert them to polygon(s).
If the result is no polygon, there is many problems...
If the result is a single polygon, this polygon can be opened if the first and last points are different.
If the result is several polygons or some polygons and single lines, the problems are between them.
All intermediarie points of polygon(s) prove that these points of the lines was equal.
I don't know if it is clear and if that responds to your question.

Eric Pousse
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