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Making a negative of a layout and other polygon operations

Question asked by ROB_LEFEBVRE on May 23, 2003
LAYOUT includes sophisticated algorithms for combining polygons.  It is easy to:

1) Make a coplanar ground with a ground spacing around complex shapes.

2) Make a negative of a layout (reverse image).

3) By taking a negative twice, shapes can be combined into a single polygon.
Note: This operation is generally not necessary, as all of the export formats
(gerber, dxf, etc.) have a "Resolve to Polygons" option which does this automatically.


4) Add an "etch" compensation factor during export ("etch" column in export table)
which increases or decreases the size of polygons to compensate for over/under etching.

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This example will show how to make a negative.

1.  Load or create the positive image of the layout.  The first figure below shows
the starting layout.

2.  Draw a rectangle around the layout which is the size of the negative image
you want to make (next figure below).

3. Select the Pour Polygon tool.  Make the settings as in the next figure below
and click OK.  Set the keep-away to zero to make the negative image the same
size as the positive.  Tolerance controls how closely the negative will follow
curves.

4.  Move the negative image off to the side.  Copy and paste to a new layout
if you need just the negative.  The final negative is shown below.

[file]negative layout.wsp[/file]

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