以下节选ObjectARX帮助文档:
C++
class AcDbLine : public AcDbCurve;
File
dbents.h
Description
The AcDbLine class represents the line entity in AutoCAD. A line object is a 3D object that is specified by its start point, endpoint, and normal vector. In addition, the line object supports thickness along its normal vector direction (that is, height or "extrusion").