ClipperOffset


The ClipperOffset class encapsulates the process of offsetting (inflating/deflating) both open and closed paths using a number of different join types and end types.

(This class replaces the now deprecated OffsetPaths function which was less flexible.)

Preconditions for offsetting:
1. The orientations of closed paths must be consistent such that outer polygons share the same orientation, and any holes have the opposite orientation (ie non-zero filling). Open paths must be oriented with closed outer polygons.
2. Polygons must not self-intersect.

Limitations:
When offsetting, small artefacts may appear where polygons overlap. To avoid these artefacts, offset overlapping polygons separately.


#include "clipper.hpp"  
...
using namespace ClipperLib;

int main()
{
  Path subj;
  Paths solution;
  subj << 
    IntPoint(348,257) << IntPoint(364,148) << IntPoint(362,148) << 
    IntPoint(326,241) << IntPoint(295,219) << IntPoint(258,88) << 
    IntPoint(440,129) << IntPoint(370,196) << IntPoint(372,275);
  ClipperOffset co;
  co.AddPath(subj, jtRound, etClosedPolygon);
  co.Execute(solution, -7.0);
  
  //draw solution ...
  DrawPolygons(solution, 0x4000FF00, 0xFF009900);
}

 

Reference

Methods Properties
In ClipperOffset:
AddPath ArcTolerance
AddPaths MiterLimit
Clear
Constructor
Execute