Create and Edit AutoCAD Entities
創建和編輯AutoCAD實體
You can create a range of objects, from simple lines and circles to spline curves, ellipses, and associative hatch areas. In general, you add objects to a BlockTableRecord object using the AppendEntity function. Once an object is created, you can change its properties such as layer, color, and linetype.
我們可以創建各種對象，從簡單的直線和圓到樣條曲線、橢圓和聯合填充區域等。通常是使用AppendEntity函數將對象添加到BlockTableRecord對象。創建了一個對象後，我們就可以修改其圖層、顏色、線型等屬性。
The drawing database is similar to other database programs, you can think of a Line object in Model space as table record and Model space as its database table. When working with a database, you must open and close records before working with them. The objects stored in the Database object are no different, you use the GetObject function to retrieve an object from the database and define how you want to work with the object.
圖形數據庫與其他數據庫程序類似，我們可以將模型空間的直線對象想象成表記錄，而將模型空間想象成數據庫表。使用數據庫時，必須在進行操作前打開和關閉記錄。對存儲在Database對象裏的對象都是一樣的，我們使用GetObject函數從數據庫中獲取一個對象，並確定怎樣使用該對象。
Topics in this section本章主題：
· Open and Close Objects 打開和關閉對象
· Create Objects 創建對象
· Work with Selection Sets 使用選擇集
· Edit Named and 2D Objects 編輯命名2D對象
· Use Layers, Colors, and Linetypes 使用圖層、顏色和線型
· Save and Restore Layer States 保存和恢復圖層狀態
· Add Text to Drawings 往圖形添加文字
感覺這一章內容較多，不管怎樣，有開始比什麼都重要。
——譯者
