objectarx已经获取AcGePoint3dArray，写代码实现绘制出二维多段线，附详细代码并注释

好的，下面是示例代码，注释已经详细说明每一步的作用：

// 获取AcGePoint3dArray
AcGePoint3dArray pts;
// 假设已经获取了pts，这里不再赘述

// 获取当前数据库
AcDbDatabase* pDb = acdbHostApplicationServices()->workingDatabase();

// 开始事务
AcDbTransaction* pTrans = pDb->transactionManager()->startTransaction();

// 新建二维多段线
AcDbPolyline* pPline = new AcDbPolyline;

// 设置顶点数目
pPline->setNumVerts(pts.length());

// 逐个添加顶点
for (int i = 0; i < pts.length(); i++) {
    // 将AcGePoint3d转换为AcGePoint2d
    AcGePoint2d pt(pts[i].x, pts[i].y);
    // 添加顶点
    pPline->addVertexAt(i, pt);
}

// 将多段线添加到模型空间
AcDbBlockTable* pBlockTable;
pTrans->getObject(pBlockTable, AcDb::kForWrite);
AcDbBlockTableRecord* pBlockTableRecord;
pTrans->getObject(pBlockTableRecord, pBlockTable->modelSpaceId(), AcDb::kForWrite);
pBlockTableRecord->appendAcDbEntity(pPline);

// 提交事务
pTrans->commit();

// 释放资源
delete pPline;

以上代码可以将AcGePoint3dArray数组中的点绘制成一条二维多段线，并将它添加到当前数据库的模型空间中。