Auto Lisp 快速上手應用小程式 - E03

Change Layer 變更圖層的小程式

此程式先讓 USER 選取要變更圖層的多個物件 . 而要變更的最終圖層 , 則以簡單的選取一個物件來指定所要圖層 . 所有先前選取的物件 , 都將被變更圖層到指定的圖層 . 要測試此程式 , 需先在不同圖層畫上多個圖元 .

(defun c:chlayer (/ a1 a2 n index b1 b2 d1 d2 b3)

(graphscr)

(prompt "nselect entities to be changed: ")

(setq a1 (ssget))

(prompt "npoint to entity on target layer: ")

(setq a2 (entsel))

(setq n (sslength a1))

(setq index 0)

(setq b2 (entget (car a2)))

(setq d2 (assoc 8 b2))

(repeat n

(setq b1 (entget (ssname a1 index)))

(setq d1 (assoc 8 b1))

(setq b3 (subst d2 d1 b1))

(entmod b3)

(setq index (+ index 1))

)

(princ)

)

現在 , 一行一行來檢查 , 說明 :

(defun c:chlayer (/ a1 a2 n index b1 b2 d1 d2 b3)

Defines the function with all local variables. 定義功能函數 , 並指定區域變數

(graphscr)

Changes to graphics screen. 切換到繪圖螢幕

(prompt "nSelect entities to be changed: ")

This is a prompt statement. 提示 : 選取要變更圖層的圖元

(setq a1 (ssget))

Allows you to select the objects to be changed. 由 USER 選取欲變更圖層的物件

The selection set is assigned to variable a1 . 將此選擇集指派給變數 a1

(prompt "npoint to entity on target layer: ")

This is a prompt statement. 提示 : 選取目標圖層的單一圖元

(setq a2 (entsel))

This is a special type of selection statement that allows you to select only one entity.

(setq n (sslength a1))

Measures the number of entities in the selection set in variable a1 .

將選集 a1 中的圖元個數值 , 指派給變數 n.

(setq index 0)

Sets the variable called index to 0 . 設定計數的起始變數 index 的值為 0.

(setq b2 (entget (car a2)))

This statement gets the entity list from a2 . Thus, a2 is assigned the entity list.

(setq d2 (assoc 8 b2))

This looks for the code 8 ( 圖層代碼 ) in entity list a2 , then assigns the sublist to d2 .( 取得目標圖層的圖層名稱 , 然後指定為替代圖層的變數 d2)

(repeat n

This begins the loop that pages through the selection set. 開始執行變更圖層的廻圈

(setq b1 (entget (ssname a1 index)))

This gets the entity list and assigns it to b1 . 依序取出各圖元的串列資料

(setq d1 (assoc 8 b1))

Gets the sublist code 8 (the layer). 取出圖層的串列資料

(setq b3 (subst d2 d1 b1))

Substitutes the new d2 layer for the old d1 layer in the entity list a1 , and assigns it to the new entity list b3 . 新圖層串列替代舊圖層串列資料 , 然後指派給新的圖元串列

(entmod b3)

Updates the new entity list in the database. 更新資料庫中的圖元資訊

(setq index (+ index 1))

Increases the index variable by 1 , making it ready for the next loop. 計數變數加 1, 繼續處理下一個圖元 , 直到和欲變更圖層圖元個數相同為止

The first ) closes the repeat loop. (princ) exits quitly. The second ) closes the function.

第一個右括號是結束廻圈的 , 第二個右括號則是結束功能函數 .

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