VARKON Version 1.15 1997-10-16

### Circular arcs

A circular arc (or just an arc in VARKON) can be a complete circle or only a part of a circle. Arc:s are planar curves with constant curvature and the sense of direction for an arc is always anticlockwise. This implies that an arc must have two ends just like a line or a curve and this is true even for a complete circle. The parametrisation along an arc is 0 where it starts and 1 where it ends and the parameter is relative to arc length.
There are 5 ways to create an arc....
arc_1pos(id,p1,radius,angle_1,angle_2); ! 1 position, radius and angles
arc_2pos(id,p1,p2,radius); ! 2 positions and radius
arc_3pos(id,p1,p2,p3); ! 3 positions
arc_offs(id,other_arc,offset); ! Offset to other arc
arc_fil(id,other_etity_1,other_entity_2,radius,alternative); ! Fillet
Since arcs are planar curves they are always created in the XY-plane of the active coordinate system. An arc created using arc_1pos starts in angle_1 and turns anticlockwise until angle_2 is reached. An arc_2pos starts in p1 and turns anticlockwise until p2 is reached. arc_3pos starts in p1, turns anticlockwise through p2 and ends in p3.
arc_fil creates an arc tangent to two lines, arcs or curves. The result depends on the parameter named alternative which selects one of the four possible solutions (corners).
An arc can be converted to a curve using cur_comp.

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