/**
* 坐标转换，与clipper库交互必须坐标转换
* @param polygon
* @return
*/
public static Path scaleUp2ClipperCoordinates(NestPath polygon)
{
Path p = new Path();
foreach (Segment s in polygon.getSegments())
{
ClipperCoor cc = CommonUtil.toClipperCoor(s.x, s.y);
p.Add(new IntPoint(cc.getX(), cc.getY()));
}
return(p);
}
public static Path NestPath2Path(NestPath nestPath)
{
Path path = new Path();
foreach (Segment s in nestPath.getSegments())
{
ClipperCoor coor = CommonUtil.toClipperCoor(s.getX(), s.getY());
var lp = new IntPoint(coor.getX(), coor.getY());
path.Add(lp);
}
return(path);
}
public static List <NestPath> polygonOffset(NestPath polygon, double offset)
{
List <NestPath> result = new List <NestPath>();
if (offset == 0 || GeometryUtil.almostEqual(offset, 0))
{
/**
* return EmptyResult
*/
return(result);
}
Path p = new Path();
foreach (Segment s in polygon.getSegments())
{
ClipperCoor cc = toClipperCoor(s.getX(), s.getY());
p.Add(new IntPoint(cc.getX(), cc.getY()));
}
int miterLimit = 2;
ClipperOffset co = new ClipperOffset(miterLimit, Config.CURVE_TOLERANCE * Config.CLIIPER_SCALE);
co.AddPath(p, JoinType.jtRound, EndType.etClosedPolygon);
Paths newpaths = new Paths();
co.Execute(ref newpaths, offset * Config.CLIIPER_SCALE);
/**
* 这里的length是1的话就是我们想要的
*/
for (int i = 0; i < newpaths.Count; i++)
{
result.Add(CommonUtil.clipperToNestPath(newpaths[i]));
}
if (offset > 0)
{
NestPath from = result[0];
if (GeometryUtil.polygonArea(from) > 0)
{
from.reverse();
}
from.add(from.get(0)); from.getSegments().RemoveAt(0);
}
return(result);
}