怎样求封闭图形的面积

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怎样求图形中封闭区域的面积 以及自动绘制封闭区域
CAD本身提供了boundary 怎样编程实现

XDSoft

You can use the command line version of the "BOUNDARY" AutoCAD command. For
example, you can use the following function call:


ads_command(RTSTR,"_.-boundary", 0 );
Using the _. prefix on the command ensures that the original boundary command
is invoked, even if the command has been redefined. If you want to allow just
one point selection, you can use the following:


ads_command(RTSTR,"_.-boundary",RTSTR, "\\", RTSTR, "", 0);
When you know the internal point, you can use the following code:


struct resbuf *arglist;
ads_point pt1;      //pt1 is an internal area point

pt1[X] = 7.0;
pt1[Y] =5.0;
pt1[Z]=0.0;

arglist = ads_buildlist(RTSTR, "_.-boundary", RTPOINT, pt1, RTSTR, "", 0);

ads_cmd(arglist);
ads_relrb(arglist);

XDSoft

There is not an ARX function that will find the boundary of a point by selecting the point inside an area enclosed by entities. A quick workaround to consider would be to find the boundary of a point by using the command line version of the boundary command.  "-Boundary"

This example creates a boundary for the selected point.



void asdkpboundary()
{
  ads_point pt;
  ads_name pent;
  acedGetPoint(NULL, L"Pick a point: ", pt);  
  acedCommand(RTSTR, L"-boundary", RTPOINT, pt, RTSTR, L"", RTNONE);
  acdbEntLast(pent);
  acedRedraw(pent, 3);
}

csharp

ARX  2015

Acad::ErrorStatus acedTraceBoundary(
    const AcGePoint3d& seedPoint,
    bool detectIslands,
    AcDbVoidPtrArray& resultingBoundarySet
);

Point3d seedPoint	The seed point, in UCS, for the boundary trace.
[MarshalAs(UnmanagedType.U1)] bool detectIslands	A boolean indicating whether or not to detect islands.

Returns

The resulting boundary set in a DBObjectCollection if the operation completed sucessfully. When called with detectIslands set to false, the result contains only one entry, representing the outer boundary. When called with detectIslands set to true, the result contain multiple entries. In this case, the last entry is the outermost boundary, and the succeeding entries represent the islands found.

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Returns the resulting boundary set in a DBObjectCollection

csharp

ARX 2015

Acad::ErrorStatus acedTraceBoundary(
    const AcGePoint3d& seedPoint,
    bool detectIslands,
    AcDbVoidPtrArray& resultingBoundarySet
);

Point3d seedPoint	The seed point, in UCS, for the boundary trace.
[MarshalAs(UnmanagedType.U1)] bool detectIslands	A boolean indicating whether or not to detect islands.

Returns

The resulting boundary set in a DBObjectCollection if the operation completed sucessfully. When called with detectIslands set to false, the result contains only one entry, representing the outer boundary. When called with detectIslands set to true, the result contain multiple entries. In this case, the last entry is the outermost boundary, and the succeeding entries represent the islands found.

Returns the resulting boundary set in a DBObjectCollection