Topic: Pick two points and draw rectangular box

[Coder]

Hi guys,

I would like to create the two red lines to be able to create the complete box as in the attached image.

User options to pick the two points (pt1 & pt2) or (pt2 & pt1) then the program to create the two red lines with or without the next two green lines.

Thank you.

[Lee Mac]

More information is required - without a constraint on the angle of the rectangle, there is no unique solution:

[Coder]

Thanks Lee .

I mean the smallest shape and that represents a wall .

I am attaching the sample .

[Lee Mac]

I mean the smallest shape and that represents a wall .

But the rectangle could be made zero size if the longest edges are parallel to the given line.

[CAB]

Coder you must decide on a pre set wall thickness or have a user input.

[Coder]

I am sorry for the confusion 

I already have the wall thickness and that is collected as a user input before asking the user to specify the two points and it is 0.2 currently.

many thanks.

[Kerry]

Coder,
Do you know how to determine the 2 points ?

and the distance between them ?

and the actual angle of the diagonal line ?

[Coder]

Hi Kerry.

that is all I know for this task. 

Code: [Select]

(setq pt1 (getpoint "\nPlease pick the first point :"))
(setq pt2 (getpoint "\nPlease pick the second point :" pt1))
(setq len (distance pt1 pt2))
(setq ang (angle pt1 pt2))


[Kerry]

Good,
Can you calculate the sharp angle ? call it ang-a

Sin sharpAngle = a / c
where a  short side and c is the len p1 p2 .


Then calculate the longside (call it b )
b = sqrt ( (c*c )- (a+a))

added:
can we agree on a length for the short side  a ?
Your drawing is 0.2723

[Kerry]

These may help later

Code - Auto/Visual Lisp: [Select]

1.  
2. ;;;  Convert Angles from DEGREES to RADIANS
3.  
4. (defun kdub:dtr (ang) (* (/ ang 180.0) pi))
5.  
6. ;;; Convert Angles from RADIANS to DEGREES
7.  
8. (defun kdub:rtd (ang) (/ (* ang 180.0) pi))
9.  
10.  
11. ;;;
12. ;;; arccosine (inverse cosine)
13. ;;; argument in the range -1.0 to 1.0 inclusive
14. ;;; returns an angle in radians in the range pi to 0 inclusive
15. ;;;
16. (defun kdub:acos (num)
17.   (if (zerop num)
18.     (* pi 0.5)
19.     (atan (sqrt (- 1.0 (* num num))) num)
20.   )
21. )
22.  
23.  
24. ;;;
25. ;;; arccosine (inverse cosine)
26. ;;; argument in the range -1.0 to 1.0 inclusive
27. ;;; arcsine (inverse sine) accepts an argument in the range
28. ;;; -1.0 to 1.0 inclusive, and returns an angle in radians in
29. ;;; the range -pi/2 to pi/2 inclusive.
30. (defun kdub:asin (num)
31.   (cond
32.     ((> (abs num) 1.0)
33.      (alert (strcat " Arc-sine error in (KDUB:asin ." "\n Spitting the dummy"))
34.      (exit)
35.     )
36.     ((zerop num) 0.0)
37.     ((= num 1.0) *:rad90)
38.     ((= num -1.0) (- *:rad90))
39.     (t (atan num (sqrt (- 1.0 (* num num)))))
40.   )
41. )
42.  
43.  

[Coder]

I am weak at maths and due to this I am asking for help in this experts forum.

I couldn't come up with an answer for your questions. sorry

[Kerry]

Can you relate to these ??

Code - Auto/Visual Lisp: [Select]

1.  
2. ;; short side
3. (setq a 0.272270 )
4.  
5. (setq pt1 (getpoint) )       ;-> (28.0686 9.16972 0.0)  
6.  
7. (setq pt2 (getpoint) )       ;-> (30.7512 12.2374 0.0)
8.  
9. ;; diagonal
10. (setq c (distance pt1 pt2))   ;-> 4.07513
11.  
12. ;; angle in World
13. (setq ang (angle pt1 pt2))    ;-> 0.852261
14. (kdub:rtd ang )               ;-> 48.8309
15.  
16. ;;  longSide
17. (setq  b (sqrt (- (* c c) (* a a)))) ;=> 4.066024
18.  
19. ;; angle opposite side b
20. (setq ang-b (kdub:acos (/ a c) )) ;-> 1.50393
21. (kdub:rtd ang-b )                 ;-> 86.1686
22.  
23. ;; angle opposite side a
24. (setq ang-a (kdub:asin (/ a c))) ;-> 0.0668698
25. (kdub:rtd ang-a )                ;-> 3.83136
26.  
27.  

revised: change the length of short side
Do you know how the polar function works ?

[Kerry]

Code - Auto/Visual Lisp: [Select]

1.  
2. (setq pt1a (polar pt1 (+ ang ang-b) a))   ;-> (27.876 9.36225 0.0)
3. (setq pt2a (polar pt2 (+ ang ang-b) (- a)))  ;-> (30.9437 12.0448 0.0)
4.  
5.  

revised: minus dim a

Then do you know how to draw 2 lines ?
from
pt1 to pt1a

from pt2 to pt2a


Note. All the dimensions and angles are taken from your drawing, so they are easily checked.
There is a slight discrepancy because of the actual length of the short side

[Coder]

Thank you Kerry for all of this inputs.

I think pt2a is not accurate and its angle is not 90 degree. can you please have a look?

[Kerry]

Points adjusted in previous post.