Topic: [AcBr(5)]Determine the positional relationship between points and closed curves

[xdcad]

ARX can determine the positional relationship between the point and AcBrFace through the AcBr API.

AcBrFace::getPointRelationToFace Function
AcBr::ErrorStatus
getPointRelationToFace(
const AcGePoint3d& point,
AcBr::Relation& relation) const;

point	AcGe point object
relation	AcBr relation enum

AcBr::Relation Enum
These are the ErrorStatus enumerated values used by getPointRelationToXXX() and getCurveRelationToXXX() functions. These enumerated types and the functions that use them are deprecated in favor of the newer getPointContainment() and getLineContainment() functions, along with the new AcGe::PointContainment enumerated type.
Relation.


The following is the ARX implementation code:

Code - C++: [Select]

1. static void BrepPointCheckPoint(void)
2. {
3.   Acad::ErrorStatus es;
4.   AcBr::ErrorStatus ebr;
5.   ads_name en;
6.   ads_point pt;
7.   if (acedEntSel(_T("\nSelect contour: "), en, pt) != RTNORM)
8.     return;
9.   AcDbObjectId eId; acdbGetObjectId(eId,en);
10.   AcDbObjectPointer<AcDbCurve> pline(eId,AcDb::kForRead) ;
11.   if ((es = pline.openStatus()) != Acad::eOk) {
12.     acutPrintf(_T("\npline.openStatus()=%s"),acadErrorStatusText(es));
13.     return;
14.   }
15.   if (acedGetPoint(pt,_T("\nPick point: "), pt) != RTNORM)
16.     return;
17.  
18.   AcDbVoidPtrArray ar, regions;
19.   ar.append(pline.object());
20.   if ((es = AcDbRegion::createFromCurves(ar,regions)) != Acad::eOk)  {
21.     acutPrintf(_T("\nAcDbRegion::createFromCurves(ar,regions)=%s"),acadErrorStatusText(es));
22.     return;
23.   }
24.   AcDbRegion reg; reg.copyFrom((AcDbRegion *)regions[0]);
25.   for (int i=0; i<regions.length();i++) delete regions[i];
26.   AcBrBrep brEnt;  ebr = brEnt.set(reg);
27.   if (ebr != AcBr::eOk) {
28.     acutPrintf(_T("\nbrEnt.set(sol)=%s"),acadErrorStatusText((Acad::ErrorStatus)(Adesk::UInt32)ebr));
29.     return;
30.   }
31.   AcGe::PointContainment pDesc;
32.   AcBrEntity *pCont = NULL;
33.   AcBrBrepFaceTraverser brepFaceTrav; brepFaceTrav.setBrep(brEnt);
34.   AcBr::ErrorStatus err = AcBr::eInvalidInput;
35.   while (!brepFaceTrav.done()) {
36.    AcBrFace brFace; brepFaceTrav.getFace(brFace);
37.    err = brFace.getPointContainment(asPnt3d(pt),pDesc,pCont);
38.    if (err == Acad::eOk && pDesc == AcGe::kInside) {
39.      acedAlert(_T("In")); return;
40.    } else if (err == Acad::eOk && pDesc == AcGe::kOnBoundary) {
41.      acedAlert(_T("On")); return;
42.    }
43.    brepFaceTrav.next();
44.   }
45.   if (err == Acad::eOk) {
46.     acedAlert(_T("Out"));
47.   } else {
48.     acedAlert(_T("Unknown error"));
49.   }
50.   return;
51. }

Below we use the AcBr library function encapsulated by the XDRX API to translate the above ARX code to LISP:

Define a function _isPtInPoly
Parameters: pl ---- closed curve
pnt ---- test point

Return value: 1: outside, 2: inside, 3, on the boundary

Code - Auto/Visual Lisp: [Select]

1. (defun _isPtInPoly (pl pnt / ss brep tr face region relation)
2.   (if (setq ss (xdrx_region_make pl t)) ;PL generates REGION
3.     (progn
4.       (setq brep (xdbr::constructor (setq region (entlast))))
5.       ;;Construct AcBrBrep object
6.       (setq tr (xdbr::constructor "brepfacetraverser" brep))
7.       ;;Build Brep to Face traverser
8.  
9.       ;;FACE traversal
10.       (while (not (xdbr::traverser:done tr))
11.         ;;The traverser has not reached the end, looping
12.         (setq face (xdbr::getpropertyvalue tr "face"))
13.         ;;Get the AcBrFace object at the current traversal position
14.         (setq relation (xdbr::getpropertyvalue
15.                          face
16.                          "PointRelationToFace"
17.                          pnt
18.                        )
19.         )
20.         ;;Use the PointRelationToFace method to determine the positional relationship between points and faces
21.         (xdrx_object_release face)
22.         ;;Release the face object
23.         (xdbr::traverser:next tr)
24.         ;;The traverser points to the next face
25.       )
26.       (xdrx_entity_delete region)
27.       ;;Delete temporary REGION
28.       (xdrx_object_release tr brep)
29.       ;;Release AcBrBrep object and traverser object
30.     )
31.   )
32.   relation
33. )
34.  

The following is a point monitor used to test the positional relationship between the mouse point and the closed curve, and print it to the screen.

Code - Auto/Visual Lisp: [Select]

1. (defun c:tt ()
2.   (defun _callback (dynpt / str)        ; point monitor callback function
3.     (if (not (setq testpnt (osnap dynpt "nea")))
4.       (setq testpnt dynpt)
5.     )
6.     (setq relation (_isPtInPoly crv testpnt))
7.                                         ; The callback function internally calls the point position judgment function _isPtInPoly
8.     (cond ((= relation XD:kInside)
9.            (setq str "The current mouse is inside the polyline!")
10.           )
11.           ((= relation XD:kBoundary)
12.            (setq str "The current mouse is on the polyline!")
13.           )
14.           (t (setq str "The current mouse is outside the polyline!"))
15.     )
16.     str
17.   )
18.   (if (setq crv (car (xdrx_entsel
19.                        "\nPick closed polyline<Exit>:"
20.                        '((0 . "LWPOLYLINE") (-4 . "&=") (70 . 1))
21.                      )
22.                 )
23.       )
24.     (progn
25.       (xdrx_begin)
26.       (xdrx_sysvar_push '("osmode" 0))
27.       (xdrx_pointmonitor "_callback")   ;Enable point monitor
28.       (getpoint
29.         "\nMove the mouse and determine the relationship between the current mouse point and the polyline<Exit>:"
30.       )
31.       (xdrx_pointmonitor)               ;Close point monitor
32.       (xdrx_end)
33.     )
34.   )
35.   (princ)
36. )

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The above LISP code uses the XDRX-API, which can be downloaded from https://github.com/xdcad/XDrx-API

The XDRX API encapsulates AcDb, AcEd, AcGe, AcBr... C++ library, using C++ methods to develop LISP programs.Thousands of Lisp functions are available.