基于DWGdirect读取DWG文件

DWGdirect是一种DWG文件的读取和写入库，可以用于在自己的应用程序中读取DWG文件。以下是基于DWGdirect读取DWG文件的示例代码：

#include <dwgdirect.h>

int main()
{
    const char* filename = "example.dwg";
    AcDbDatabase* database = new AcDbDatabase(false, true);
    if (database->readDwgFile(filename) != Acad::eOk) {
        delete database;
        return 1;
    }

    //遍历所有实体
    AcDbBlockTable* blockTable;
    database->getBlockTable(blockTable, AcDb::kForRead);
    AcDbBlockTableIterator* blockTableIterator;
    blockTable->newIterator(blockTableIterator);
    for (; !blockTableIterator->done(); blockTableIterator->step()) {
        AcDbBlockTableRecord* blockTableRecord;
        blockTableIterator->getRecord(blockTableRecord, AcDb::kForRead);
        AcDbBlockTableRecordIterator* blockTableRecordIterator;
        blockTableRecord->newIterator(blockTableRecordIterator);
        for (; !blockTableRecordIterator->done(); blockTableRecordIterator->step()) {
            AcDbEntity* entity;
            blockTableRecordIterator->getEntity(entity, AcDb::kForRead);
            //处理实体
            entity->close();
        }
        delete blockTableRecordIterator;
        blockTableRecord->close();
    }
    delete blockTableIterator;
    blockTable->close();

    delete database;
    return 0;
}

此代码打开一个DWG文件并遍历其中的所有实体。在实际应用中，您可能需要根据自己的具体需求修改代码。