[每日一码] ARX射线法判断点是否在多边形内

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1. //*************************************************************
2. //利用射线法判断一点是否在窗口内，如果在内部返回1，否则返回0
3. //其中输入参数pt是被判断点，boundarypt是辅助边界点，用于作射线用
4. //*********************1-14-2001 by Meishuli
6. int inwindow(ads采用point pt,ads采用point boundarypt,ads采用name windowent)
7. {
8.   ads采用name ent0;
9.   int rt;
11.   AcDbEntity *pent,*pwindowent;
12.     AcDbObjectId pentId,pwindowentId;
13.   AcGePoint3dArray points;
14.   int CrossPtsNum;
15.   AcGePoint3d Pts,BoundaryPts;
16.   AcDbObjectId auxlineId;
17.     Acad::ErrorStatus es;
19.   Pts.set(pt[X],pt[Y],0);
20.   BoundaryPts.set(boundarypt[X],boundarypt[Y],0);
22.   auxlineId=createLine(Pts,BoundaryPts);
23.   acdbEntLast(ent0);
25.   pwindowent=selectEntity(pwindowentId,windowent,AcDb::kForRead);
26.   pent=selectEntity(pentId,ent0,AcDb::kForRead);
28.   es=pwindowent->intersectWith(pent,AcDb::kOnBothOperands,points,0,0);
29.     if (es == Acad::eOk) {
30.       CrossPtsNum=points.length(); //计算交点的数量CrossPtsNum
31.         points.setLogicalLength(0);
32.   }
33.   else {
34.         acutPrintf("\nerror!--inwindow()\n");
36.       pent->close();
37.     acdbEntDel(ent0);
38.       pwindowent->close();
39.     return -1;
40.   }
41.   pent->close();
42.   acdbEntDel(ent0);
44.   pwindowent->close();
45.   if(CrossPtsNum % 2 == 0)
46.      rt = 0;
47.   else rt = 1;
48.   return rt;
49. }

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