;;; ============================================================
;;; 圆弧长度修改程序（优化版）
;;; 保持圆心、半径不变，仅通过调整结束角度控制长度
;;;原代码来源于明经CAD社区，由CADCHAJIAN.COM修改完善
;;;ChangeArcLength             - 修改单个圆弧长度
;;;ChangeArcLengthExact     - 精确修改(显示详细信息)
;;;ChangeMultipleArcsLength - 批量修改多个圆弧
;;;ArcInfo                  - 查看圆弧详细信息
;;;命令较长是为防止冲突，可自定义快捷键
;;; ============================================================

;;; 通用函数：获取圆弧方向 (T=逆时针, nil=顺时针)
(defun GetArcDirection (arc_ename / arc_obj)
  (setq arc_obj (vlax-ename->vla-object arc_ename))
  (if (= (vla-get-totalangle arc_obj) 
         (vla-get-totalangle arc_obj)) ; 确保对象有效
    (progn
      ;; 通过TotalAngle的正负判断方向（正=逆时针）
      (> (vla-get-totalangle arc_obj) 0)
    )
    nil
  )
)

;;; 通用函数：安全更新圆弧结束角度
(defun UpdateArcEndAngle (arc_ename start_ang new_total_ang direction / arc_data)
  (setq arc_data (entget arc_ename))
  (if direction  ; T=逆时针
    (entmod (subst (cons 51 (+ start_ang new_total_ang)) (assoc 51 arc_data) arc_data))
    (entmod (subst (cons 51 (- start_ang new_total_ang)) (assoc 51 arc_data) arc_data))
  )
  (entupd arc_ename)
)

;;; 1. 修改单个圆弧长度（简洁版）
(defun c:ChangeArcLength (/ ss arc_ent arc_obj current_length new_length 
                            radius start_angle direction new_angle)
  (vl-load-com)
  
  (princ "\n选择要修改长度的圆弧: ")
  
  (if (setq ss (ssget ":S" '((0 . "ARC"))))
    (progn
      (setq arc_ent (ssname ss 0)
            arc_obj (vlax-ename->vla-object arc_ent)
            current_length (vla-get-arclength arc_obj)
            radius (vla-get-radius arc_obj)
            start_angle (vla-get-startangle arc_obj)
            direction (GetArcDirection arc_ent))
      
      (princ (strcat "\n当前圆弧长度: " (rtos current_length 2 2)))
      (princ (strcat "\n圆弧半径: " (rtos radius 2 2)))
      
      (initget 7)
      (setq new_length (getreal "\n请输入新的圆弧长度: "))
      
      (if new_length
        (progn
          (setq new_angle (/ new_length radius))
          
          ;; 限制最大角度
          (if (> new_angle (* 2 pi))
            (progn
              (princ "\n警告: 新长度超过圆周长，将限制为整圆")
              (setq new_angle (* 2 pi))
            )
          )
          
          (UpdateArcEndAngle arc_ent start_angle new_angle direction)
          
          (princ (strcat "\n圆弧长度已修改为: " 
                        (rtos (* radius new_angle) 2 2)))
        )
      )
    )
  )
  (princ)
)

;;; 2. 精确修改单个圆弧长度（信息详细版）
(defun c:ChangeArcLengthExact (/ ss arc_ent arc_obj current_length new_length 
                                 radius start_angle end_angle direction new_angle)
  (vl-load-com)
  
  (princ "\n选择要修改长度的圆弧: ")
  
  (if (setq ss (ssget ":S" '((0 . "ARC"))))
    (progn
      (setq arc_ent (ssname ss 0)
            arc_obj (vlax-ename->vla-object arc_ent))
      
      ;; 获取圆弧属性
      (setq radius (vla-get-radius arc_obj)
            start_angle (vla-get-startangle arc_obj)
            end_angle (vla-get-endangle arc_obj)
            current_length (vla-get-arclength arc_obj)
            direction (GetArcDirection arc_ent))
      
      ;; 显示当前信息
      (princ "\n=== 当前圆弧信息 ===")
      (princ (strcat "\n半径: " (rtos radius 2 2)))
      (princ (strcat "\n起始角度: " (rtos (* (/ start_angle pi) 180) 2 4) "°"))
      (princ (strcat "\n结束角度: " (rtos (* (/ end_angle pi) 180) 2 4) "°"))
      (princ (strcat "\n方向: " (if direction "逆时针" "顺时针")))
      (princ (strcat "\n当前长度: " (rtos current_length 2 4)))
      
      ;; 获取新长度
      (initget 7)
      (setq new_length (getreal "\n请输入新的圆弧长度: "))
      
      (if new_length
        (progn
          (setq new_angle (/ new_length radius))
          
          ;; 检查并限制角度
          (cond
            ((> new_angle (* 2 pi))
             (princ (strcat "\n警告: 新长度 " (rtos new_length 2 2) 
                           " 超过圆周长 " (rtos (* 2 pi radius) 2 2)))
             (setq new_angle (* 2 pi))
             (princ "\n已将角度限制为360°"))
            ((< new_angle 0.0001)
             (princ "\n警告: 新长度过小"))
          )
          
          ;; 更新圆弧
          (UpdateArcEndAngle arc_ent start_angle new_angle direction)
          
          ;; 显示结果
          (princ "\n=== 修改后信息 ===")
          (princ (strcat "\n新长度: " (rtos (* radius new_angle) 2 4)))
          (princ (strcat "\n新角度: " (rtos (* (/ new_angle pi) 180) 2 4) "°"))
        )
      )
    )
  )
  (princ)
)

;;; 3. 批量修改多个圆弧长度
(defun c:ChangeMultipleArcsLength (/ ss i arc_ent arc_obj radius start_angle 
                                     direction new_length new_angle count modified)
  (vl-load-com)
  
  (princ "\n选择要批量修改长度的圆弧: ")
  
  (if (setq ss (ssget '((0 . "ARC"))))
    (progn
      (setq count (sslength ss))
      (princ (strcat "\n已选择 " (itoa count) " 个圆弧"))
      
      ;; 获取新长度
      (initget 7)
      (setq new_length (getreal "\n请输入统一的新长度: "))
      
      (if new_length
        (progn
          (setq modified 0)
          (repeat (setq i count)
            (setq arc_ent (ssname ss (setq i (1- i)))
                  arc_obj (vlax-ename->vla-object arc_ent)
                  radius (vla-get-radius arc_obj)
                  start_angle (vla-get-startangle arc_obj)
                  direction (GetArcDirection arc_ent)
                  new_angle (/ new_length radius))
            
            ;; 限制最大角度
            (if (> new_angle (* 2 pi))
              (setq new_angle (* 2 pi))
            )
            
            ;; 更新圆弧
            (UpdateArcEndAngle arc_ent start_angle new_angle direction)
            (setq modified (1+ modified))
          )
          
          (princ (strcat "\n完成！成功修改 " (itoa modified) " 个圆弧"))
          (if (/= modified count)
            (princ (strcat "\n注意: " (itoa (- count modified)) " 个圆弧可能有问题"))
          )
        )
      )
    )
  )
  (princ)
)

;;; 4. 圆弧信息显示
(defun c:ArcInfo (/ ss arc_ent arc_obj center radius start_angle end_angle 
                    total_angle arc_length direction)
  (vl-load-com)
  
  (princ "\n选择要查看信息的圆弧: ")
  
  (if (setq ss (ssget ":S" '((0 . "ARC"))))
    (progn
      (setq arc_ent (ssname ss 0)
            arc_obj (vlax-ename->vla-object arc_ent))
      
      (setq center (vlax-get arc_obj 'Center)
            radius (vla-get-radius arc_obj)
            start_angle (vla-get-startangle arc_obj)
            end_angle (vla-get-endangle arc_obj)
            total_angle (vla-get-totalangle arc_obj)
            arc_length (vla-get-arclength arc_obj)
            direction (if (> total_angle 0) "逆时针" "顺时针"))
      
      (princ "\n═══════ 圆弧详细信息 ═══════")
      (princ (strcat "\n圆心坐标: (" 
                    (rtos (car center) 2 4) ", " 
                    (rtos (cadr center) 2 4) ", " 
                    (rtos (caddr center) 2 4) ")"))
      (princ (strcat "\n半径: " (rtos radius 2 4)))
      (princ (strcat "\n起始角度: " (rtos (* (/ start_angle pi) 180) 2 4) "°"))
      (princ (strcat "\n结束角度: " (rtos (* (/ end_angle pi) 180) 2 4) "°"))
      (princ (strcat "\n圆弧方向: " direction))
      (princ (strcat "\n圆弧角度: " (rtos (* (/ (abs total_angle) pi) 180) 2 4) "°"))
      (princ (strcat "\n圆弧长度: " (rtos arc_length 2 4)))
      (princ "\n════════════════════════════")
    )
  )
  (princ)
)

;; 加载提示
(princ "\n圆弧长度修改程序已加载 (优化版)")
(princ "\n可用命令:")
(princ "\n  ChangeArcLength          - 修改单个圆弧长度")
(princ "\n  ChangeArcLengthExact     - 精确修改(显示详细信息)")
(princ "\n  ChangeMultipleArcsLength - 批量修改多个圆弧")
(princ "\n  ArcInfo                  - 查看圆弧详细信息")
(princ)