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.