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##

The **!noacute** Command: Eliminate Acute Angles

Syntax: `!noacute`

This command will look at each currently selected polygon. For
vertices that form an acute angle, vertices will be added so that no
angle is acute, i.e. the sharp point is clipped off. This command is
useful for preprocessing the database for flash conversion or other
functions where acute angles are undesirable. It does not prevent DRC
errors, and in fact may produce them. It also produces tiny (order of
the layer's minimum dimension or one micron, if the minimum width for
the layer is not given) changes to the layout. For example, consider
a group of five or more polygons, each one of which is a pie section,
that together form a disk. Running this command will produce a hole
in the center, where the angles are clipped.
The algorithm works as follows. For each vertex *V*_{n}
of a polygon,
check the angle formed with adjacent vertices *V*_{n-1}
,*V*_{n+1}
. If
the angle is acute, construct a circle around *V*_{n}
where the radius
is the minimum of the layer's minimum dimension or the distance to the
nearest of *V*_{n-1}
,*V*_{n+1}
. Find the intersections of the circle
with segments *V*_{n}
,*V*_{n-1}
and *V*_{n}
,*V*_{n+1}
. Replace the vertex
*V*_{n}
with these two points.

** Next:** The !togrid Command: Move
** Up:** Layout Editing
** Previous:** The !polyrev Command: Reverse
** Contents**
** Index**
Stephen R. Whiteley
2021-01-27