Monty Lisp Posted July 18, 2023 Share Posted July 18, 2023 Hi All, I'm trying to get the coordinates of a centroid of multiple seperate lines. It should be a centre of gravity of lines, but taking the length as weight. (So the sum of each line's midpoint x-coordinate times its length, divided by sum of all lengths, and the same for the y-coordinate). Somehow I cannot find anywhere an example to do this yet I have the feeling it shouldn't be too difficult. I'm not too familiar with LISP but as autocad LT 2024 has the ability to load LISP files I suddenly see so many tiny processes which I can automate . I hope someone can help me, Kind regards, Monty Lisp Quote Link to comment Share on other sites More sharing options...
fuccaro Posted July 18, 2023 Share Posted July 18, 2023 Hello and welcome! Try this: (defun c:pp() (setq ssl (ssget '((0 . "LINE"))) xg 0 yg 0 zg 0 lt 0) (repeat (setq i (sslength ssl)) (setq el (entget (ssname ssl (setq i (1- i)))) p1 (cdr (assoc 10 el)) p2 (cdr (assoc 11 el)) x1 (car p1) x2 (car p2) xm (/ (+ x1 x2) 2.0) y1 (cadr p1) y2 (cadr p2) ym (/ (+ y1 y2) 2.0) z1 (caddr p1) z2 (caddr p2) zm (/ (+ z1 z2) 2.0) l (distance p1 p2) xg (+ xg (* xm l)) yg (+ yg (* ym l)) zg (+ zg (+ zg l)) lt (+ lt l) ) ) (setq ssl nil) (setq w (list (/ xg lt) (/ yg lt) (/ zg lt))) ) For sure the masters around here will post shorter and more elegant code, I tried to write the program step by step. Post again if you need more clarifications... Quote Link to comment Share on other sites More sharing options...
marko_ribar Posted July 18, 2023 Share Posted July 18, 2023 https://www.theswamp.org/index.php?topic=57619.msg610196#msg610196 HTH., M.R. Quote Link to comment Share on other sites More sharing options...
Monty Lisp Posted July 18, 2023 Author Share Posted July 18, 2023 59 minutes ago, fuccaro said: Hello and welcome! Try this: (defun c:pp() (setq ssl (ssget '((0 . "LINE"))) xg 0 yg 0 zg 0 lt 0) (repeat (setq i (sslength ssl)) (setq el (entget (ssname ssl (setq i (1- i)))) p1 (cdr (assoc 10 el)) p2 (cdr (assoc 11 el)) x1 (car p1) x2 (car p2) xm (/ (+ x1 x2) 2.0) y1 (cadr p1) y2 (cadr p2) ym (/ (+ x1 x2) 2.0) z1 (caddr p1) z2 (caddr p2) zm (/ (+ z1 z2) 2.0) l (distance p1 p2) xg (+ xg (* xm l)) yg (+ yg (* ym l)) zg (+ zg (+ zg l)) lt (+ lt l) ) ) (setq w (list (/ xg lt) (/ yg lt) (/ zg lt))) (setq ssl nil) ) For sure the masters around here will post shorter and more elegant code, I tried to write the program step by step. Post again if you need more clarifications... Thanks! Such a quick answer. There was a tiny error for y1 (you use x1 and x2 again but with my limited knowledge of LSP I updated it to y1 and y2 and it worked!) I'll dissect the code and see if i can learn some LISP as this saves me quite some time! 1 Quote Link to comment Share on other sites More sharing options...
BIGAL Posted July 19, 2023 Share Posted July 19, 2023 When you need say mid of 2 points this is handy as you dont need to work out X & Y values. Both these do the same (setq mp (mapcar '/ (mapcar '+ p1 p2) '(2.0 2.0 2.0))) ; divide by 2 (setq mp (mapcar '* (mapcar '+ p1 p2) '(0.5 0.5 0.5))) ; Multiply by 0.5 Quote Link to comment Share on other sites More sharing options...
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