【AcBr库应用（四）】求空间点到3DSOLID各个面的最近点

newer

问题：

I have a point in 3D space and I would like to get the closest point on a 3D solid from this input point. Is there any API to achieve this?


求输入点到3DSOLID最近点，哪个API可以解决？

解决方案：


It is possible to realize that using the BRep API (located in the <ObjectARX 2009 Path>\utils\brep directory): you need to traverse all the faces that are contained in your 3D solid and for each face use the AcBrFace::getFace method. It returns an AcGeSurface object from where you can use AcGeSurface::closestPointTo, passing in your input point.


使用BRep API,您需要遍历3D实体中包含的所有面，并为每个面使用AcBrFace :: getFace方法，得到AcGeSurface对象， 使用AcGeSurface :: closestPointTo获得输入点和AcGeSurface对象的最近点。



下面是ARX代码：

[C++] 纯文本查看 复制代码

static AcBr::ErrorStatus TraverseFaces(const AcBrBrep& brepEntity, const AcGePoint3d& pointToTest)
{
        AcBr::ErrorStatus returnValue = AcBr::eOk;
        // make a global face traverser
        AcBrBrepFaceTraverser brepFaceTrav;
        returnValue = brepFaceTrav.setBrep(brepEntity);
        if (returnValue != AcBr::eOk)
        {
                acutPrintf(ACRX_T("\n Error in AcBrBrepFaceTraverser::setBrep:"));
                errorReport(returnValue);
                return returnValue;
        }
        int faceCount = 0;
       while (!brepFaceTrav.done() && (returnValue == AcBr::eOk))
        {
                ++faceCount;
                AcBrFace face;
                if (brepFaceTrav.getFace(face) == AcBr::ErrorStatus::eOk)
                {
                        AcGeSurface* pSurface;
                        if (face.getSurface(pSurface) == AcBr::ErrorStatus::eOk)
                        {
                                AcGePoint3d closestPoint = pSurface->closestPointTo(pointToTest);

                                double dist = AcGeVector3d(closestPoint.asVector() - pointToTest.asVector()).length();

                                acutPrintf(L"\n - Face[%d]: closest point [%f, %f, %f]   Distance: %f", faceCount, closestPoint.x, closestPoint.y, closestPoint.z, dist);

                                delete pSurface;
                        }
                }
                returnValue = brepFaceTrav.next();
                if (returnValue != AcBr::eOk) {
                        acutPrintf(ACRX_T("\n Error in AcBrBrepFaceTraverser::next:"));
                        errorReport(returnValue);
                        return returnValue;
                }
        }
        return returnValue;
}
void TestClosestPoint(void)
{
        AcBr::ErrorStatus returnValue = AcBr::eOk;
        Acad::ErrorStatus acadReturnValue = eOk;
        AcGePoint3d pointToTest;
        // pick a point
        acedGetPoint(NULL, L"\nPick a point: ", asDblArray(pointToTest));
        // Get the subentity path for a brep
        AcDbFullSubentPath subPath(kNullSubent);
        acadReturnValue = selectEntity(AcDb::kNullSubentType, subPath);
        if (acadReturnValue != eOk)
        {
                acutPrintf(ACRX_T("\n Error in getPath: %d"), acadReturnValue);
                return;
        }
        // Make a brep entity to access the solid
        AcBrBrep brepEntity;
        returnValue = ((AcBrEntity*)&brepEntity)->set(subPath);
        if (returnValue != AcBr::eOk)
        {
                acutPrintf(ACRX_T("\n Error in AcBrBrep::set:"));
                errorReport(returnValue);
                return;
        }
        returnValue = TraverseFaces(brepEntity, pointToTest);
        if (returnValue != AcBr::eOk)
        {
                acutPrintf(ACRX_T("\n Error in TraverseFaces:"));
                errorReport(returnValue);
                return;
        }
}

下面使用XDRX API的 ACBR库函数，完成上面ARX同样的工作

1. (defun c:tt ()
   
2.   (defun _traversface (e pnt)
   
3.     (setq br (xdbr::constructor e))
   
4.     (setq tr (xdbr::constructor "brepfacetraverser" br))
   
5.     ;;FACE遍历
   
6.     (setq face-count 0)
   
7.     (xdrx_entity_delete co-ss)
   
8.     (xdrx_setmark)
   
9.     (while (not (xdbr::traverser:done tr));循环遍历
   
10.       (if (setq face (xdbr::getpropertyvalue tr "face"));;AcBrFace对象
    
11.         (progn (setq face-count  (1+ face-count)
    
12.                      gface       (xdbr::getpropertyvalue face "surface") ;;得到AcGeSurface对象
    
13.                      closest-pnt (xdge::getpropertyvalue gface "closestpointto" pnt);;最近点
    
14.                      dist        (distance pnt closest-pnt)
    
15.                )
    
16.           (xdrx_object_release gface face);;释放AcBrFace、AcGeSurface
    
17.           (xdrx_point_make closest-pnt)
    
18.           (xdrx_entity_setcolor (entlast) 2)
    
19.           (xdrx_line_make pnt closest-pnt)
    
20.           (xdrx_entity_setcolor (entlast) 1)
    
21.                (xdrx_prompt
    
22.                  (xdrx_string_format "\n - 面[%d]: 最近点 [%f, %f, %f]   距离 %f"
    
23.                                      face-count
    
24.                                      (car closest-pnt)
    
25.                                      (cadr closest-pnt)
    
26.                                      (caddr closest-pnt)
    
27.                                      dist
    
28.                  )
    
29.                )
    
30.         )
    
31.       )
    
32.       (setq co-ss (xdrx_getss))
    
33.       (xdbr::traverser:next tr)
    
34.     )
    
35.     (xdrx_object_release tr br)
    
36.   )
    
37.   (if (setq e (car (xdrx_entsel "\n选取3DSOLID<退出>:" '((0 . "3DSOLID")))))
    
38.     (progn
    
39.       (xdrx_begin)
    
40.       (xdrx_sysvar_push '("osmode" 512))
    
41.       (xdrx_setvar "pdmode" 35)
    
42.       (while (setq pt (getpoint "\n点取测试点<退出>:"))
    
43.       (_traversface e (setq pt (trans pt 1 0))))
    
44.       (xdrx_end)
    
45.     )
    
46.   )
    
47.   (princ)
    
48. )
    

(defun c:tt ()<br />   (defun _traversface (e pnt)<br />     (setq br (xdbr::constructor e))<br />     (setq tr (xdbr::constructor "brepfacetraverser" br))<br />     ;;FACE遍历<br />     (setq face-count 0)<br />     (xdrx_entity_delete co-ss)<br />     (xdrx_setmark)<br />     (while (not (xdbr::traverser:done tr));循环遍历<br />       (if (setq face (xdbr::getpropertyvalue tr "face"));;AcBrFace对象<br />         (progn (setq face-count  (1+ face-count)<br />                      gface       (xdbr::getpropertyvalue face "surface") ;;得到AcGeSurface对象<br />                      closest-pnt (xdge::getpropertyvalue gface "closestpointto" pnt);;最近点<br />                      dist        (distance pnt closest-pnt)<br />                )<br />           (xdrx_object_release gface face);;释放AcBrFace、AcGeSurface<br />           (xdrx_point_make closest-pnt)<br />           (xdrx_entity_setcolor (entlast) 2)<br />           (xdrx_line_make pnt closest-pnt)<br />           (xdrx_entity_setcolor (entlast) 1)<br />                (xdrx_prompt<br />                  (xdrx_string_format "\n - 面[%d]: 最近点 [%f, %f, %f]   距离 %f"<br />                                      face-count<br />                                      (car closest-pnt)<br />                                      (cadr closest-pnt)<br />                                      (caddr closest-pnt)<br />                                      dist<br />                  )<br />                )<br />         )<br />       )<br />       (setq co-ss (xdrx_getss))<br />       (xdbr::traverser:next tr)<br />     )<br />     (xdrx_object_release tr br)<br />   )<br />   (if (setq e (car (xdrx_entsel "\n选取3DSOLID<退出>:" '((0 . "3DSOLID")))))<br />     (progn<br />       (xdrx_begin)<br />       (xdrx_sysvar_push '("osmode" 512))<br />       (xdrx_setvar "pdmode" 35)<br />       (while (setq pt (getpoint "\n点取测试点<退出>:"))<br />       (_traversface e (setq pt (trans pt 1 0))))<br />       (xdrx_end)<br />     )<br />   )<br />   (princ)<br /> )<br />

eboy_k

好啊的，学习了

sh_h

留个脚印，以后慢慢学习！