C# cad面域合并

C# CAD面域合并是指将多个边界曲线合并成一个面域的操作。具体实现可以使用选择集，提示用户选择作为面域边界的对象，然后根据选择集中的对象构建边界曲线的ID数组。接着，使用这些边界曲线的ID数组创建面域，并将其添加到面域集合中。最后，返回面域集合中的面域数量。

下面是一个示例代码，用于实现C# CAD面域合并：

public static int MergeRegions()
{
    // 使用选择集，提示用户选择作为面域边界的对象
    PromptSelectionResult selectionResult = Application.DocumentManager.MdiActiveDocument.Editor.GetSelection();
    if (selectionResult.Status != PromptStatus.OK)
    {
        return 0;
    }

    // 根据选择集中的对象构建边界曲线的ID数组
    ObjectId[] objectIds = selectionResult.Value.GetObjectIds();
    List<ObjectId> boundaryIds = new List<ObjectId>();
    foreach (ObjectId objectId in objectIds)
    {
        Entity entity = (Entity)TransactionManager.GetObject(objectId, OpenMode.ForRead);
        if (entity is Curve)
        {
            boundaryIds.Add(objectId);
        }
    }

    // 创建面域
    List<ObjectId> regionIds = new List<ObjectId>();
    if (boundaryIds.Count > 0)
    {
        Database database = Application.DocumentManager.MdiActiveDocument.Database;
        using (Transaction transaction = database.TransactionManager.StartTransaction())
        {
            BlockTable blockTable = (BlockTable)transaction.GetObject(database.BlockTableId, OpenMode.ForRead);
            BlockTableRecord blockTableRecord = (BlockTableRecord)transaction.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);

            foreach (ObjectId boundaryId in boundaryIds)
            {
                DBObject boundaryObject = transaction.GetObject(boundaryId, OpenMode.ForRead);
                Curve boundaryCurve = boundaryObject as Curve;
                if (boundaryCurve != null)
                {
                    DBObject regionObject = boundaryCurve.GetRegion();
                    if (regionObject != null)
                    {
                        regionIds.Add(regionObject.ObjectId);
                        blockTableRecord.AppendEntity((Entity)regionObject);
                        transaction.AddNewlyCreatedDBObject(regionObject, true);
                    }
                }
            }

            transaction.Commit();
        }
    }

    // 返回面域数量
    return regionIds.Count;
}