主要思路：拾取一个点作为矩形的插入点，分别以该点进行两次jig操作，就能得到白色的两个相交的polyline，之后需要变成红色的封闭多段线。做法就是：求出两个白色矩形的面域，然后通过bool操作的并集，使得两个面域合并成一个面域。最后就把这个面域在转换成polyline就完成了。其中要注意， 要想在使用向导创建的工程里使用面域的类，需要在头文件：StdAfx.h 中写上这句宏命令#define _BREP_SUPPORT_，就不需要引用库文件了。下面给出详细代码：
拖动矩形的jig操作：
DrawRecJig::DrawRecJig()
{
pl = NULL;
}
DrawRecJig::~DrawRecJig()
{
}
AcEdJig::DragStatus DrawRecJig::sampler()
{
setUserInputControls((AcEdJig::UserInputControls)(
AcEdJig::kAccept3dCoordinates |
AcEdJig::kNoNegativeResponseAccepted |
AcEdJig::kNullResponseAccepted
));
AcGePoint3d ptTemp;
AcEdJig::DragStatus status = acquirePoint(ptTemp);
if (ptTemp != ptCurrent) {
ptCurrent= ptTemp;
}
else if (status == DragStatus::kNormal) {
return AcEdJig::kNoChange;
}
return status;
}
bool DrawRecJig::update()
{
double dist = CConvertUtil::ToPoint2d(ptCenter).distanceTo(CConvertUtil::ToPoint2d(ptCurrent));
// 提取两个角点的坐标值
double x1 = ptCenter.x, x2 = ptCurrent.x;
double y1 = ptCenter.y, y2 = ptCurrent.y;
// 计算矩形的角点
AcGePoint2d ptLeftBottom(min(x1, x2), min(y1, y2));
AcGePoint2d ptRightBottom(max(x1, x2), min(y1, y2));
AcGePoint2d ptRightTop(max(x1, x2), max(y1, y2));
AcGePoint2d ptLeftTop(min(x1, x2), max(y1, y2));
pl->setPointAt(0, ptLeftBottom);
pl->setPointAt(1, ptLeftTop);
pl->setPointAt(2, ptRightTop);
pl->setPointAt(3, ptRightBottom);
return true;
}
AcDbEntity * DrawRecJig::entity() const
{
return pl;
}
bool DrawRecJig::DoIt(AcGePoint3d & ptCenter, AcDbObjectId &plId)
{
this->ptCenter = ptCenter;
pl = new AcDbPolyline();
for (int i = 0; i < 4; i++)
{
pl->addVertexAt(i, CConvertUtil::ToPoint2d(ptCenter));
}
pl->setClosed(true);
setDispPrompt(L"请拖动鼠标：");
if (drag()==kNormal) {
//加入到模型空间的封装
plId=CDwgDataBaseUtil::PostToModelSpace(pl);
return true;
}
else {
delete pl;
return false;
}
}
命令类：
static void ECDMyGroupEUnion() {
DrawRecJig recJig = DrawRecJig();
ads_point pt;
AcDbPolyline *pl1 = NULL, *pl2 = NULL;
if (acedGetPoint(NULL, L"\n请选择插入点：", pt) == RTNORM) {
AcDbObjectId oId1, oId2;
if (recJig.DoIt(asPnt3d(pt), oId1)) {
pl1 = AcDbPolyline::cast(recJig.entity());
}
if (recJig.DoIt(asPnt3d(pt), oId2)) {
pl2 = AcDbPolyline::cast(recJig.entity());
}
AcDbVoidPtrArray curveSegments;
AcDbVoidPtrArray regions;
curveSegments.append(pl1);
curveSegments.append(pl2);
if (AcDbRegion::createFromCurves(curveSegments, regions) == Acad::eOk) {
AcDbRegion *region =(AcDbRegion *)regions[0];
region->booleanOper(AcDb::BoolOperType::kBoolUnite, (AcDbRegion *)regions[1]);
AcGePoint3dArray ptArr;
CRegionUtil::GetRegionPoints(region, ptArr);
for (int i = 0; i < regions.length (); i++)
{
AcDbRegion *regionTemp = (AcDbRegion *)regions[i];
regionTemp->erase();
regionTemp->close();
}
region->close();
AcDbPolyline *plTemp1 = new AcDbPolyline();
for (int i = 0; i <ptArr.length(); i++)
{
plTemp1->addVertexAt(plTemp1->numVerts(), CConvertUtil::ToPoint2d(ptArr.at(i)), 0, 0, 0);
}
plTemp1->setClosed(Adesk::kTrue);
plTemp1->setColorIndex(1);
CDwgDataBaseUtil::PostToModelSpace(plTemp1);
plTemp1->close();
}
pl1->close();
pl2->close();
}
}
面域转AcGePoint3d：
void CRegionUtil::GetRegionPoints(AcDbRegion* pRegion,AcGePoint3dArray &points)
{
AcBrBrep*pBrep = new AcBrBrep;
pBrep->set(*pRegion);
AcBrBrepFaceTraverser brFaTrav;
for (brFaTrav.setBrep(*pBrep); !brFaTrav.done(); brFaTrav.next())
{
AcBrFaceLoopTraverser faLoTrav;
AcBrFace face;
brFaTrav.getFace(face);
for (faLoTrav.setFace(face); !faLoTrav.done(); faLoTrav.next())
{
AcBrLoopEdgeTraverser loEdTrav;
if (loEdTrav.setLoop(faLoTrav) == AcBr::eOk)
{
for (; !loEdTrav.done(); loEdTrav.next())
{
AcBrEdge edge;
loEdTrav.getEdge(edge);
AcBrVertex start;
edge.getVertex1(start);
AcGePoint3d pt;
start.getPoint(pt);
points.append(pt);
}
} // else its an isolated loop
}
}
delete pBrep;
}
转自：https://www.cnblogs.com/HelloQLQ/p/12197133.html