Autodesk Developer Blog : Rotation angle of MText using Lisp

By Balaji Ramamoorthy

The angle of the MTEXT entity is contained in the group code 11 entry.

Consider this MTEXT entity:

Command: MTEXT

Specify first corner: 5,5

Specify opposite corner or [Height/Justify/Line spacing/Rotation/Style/Width/Columns]: R

Specify rotation angle <0>: 30

Specify opposite corner or [Height/Justify/Line spacing/Rotation/Style/Width/Columns]: @10,10

MText: Welcome

Command: (entget (entlast)) ((-1 . ) (0 . “MTEXT”) (5 . “2B”) (100 . “AcDbEntity”) (67 . 0) (8 . “0”) (100 . “AcDbMText”) (10 5.0 5.0 0.0) (40 . 0.619107) (41 . 5.0) (71 . 1) (72 . 1) (1 . “Welcome”) (7 . “STANDARD”) (210 0.0 0.0 1.0) (11 0.866025 0.5 0.0))

The rotation of the MTEXT was 30 degrees and in group code 11 we can see the values 0.866 and 0.5. These values are simply cos(30) and sin(30).

Here is a sample Lisp code :

;; Find the MText angle of rotation
(defun c:mtangle()
    (setq ed (entget (car(entsel))))
    (if (equal (cdr (assoc 0 ed)) "MTEXT")
        (progn
            (princ (* 180.0 (/ (acos (nth 1 (assoc 11 ed))) pi)))
            (princ "\n")
            (princ (* 180.0 (/ (asin (nth 2 (assoc 11 ed))) pi)))
            (princ)
        )
    )
)
 
;; Based on relation between atan and asin
;; http://en.wikipedia.org/wiki/Inverse_trigonometric_functions#Relationships_among_the_inverse_trigonometric_functions
(defun asin (x)
    (cond
        (    (equal x -1 1e-6) 
            (/ pi -2)
        )
 
        (    (equal x 1 1e-6) 
            (/ pi 2)
        )
 
        (    (< -1 x 1)
            (atan x (sqrt (- 1 (* x x))))
        )
    )
 )
 
;; Based on relation between atan and acos
;; http://en.wikipedia.org/wiki/Inverse_trigonometric_functions#Relationships_among_the_inverse_trigonometric_functions
(defun acos (x)
    (cond
        (    (equal x -1 1e-6) 
            pi
        )
 
        (    (equal x 1 1e-6) 
            0.0
        )
 
        (    (< -1 x 1)
            (atan (sqrt (- 1 (* x x))) x)
        )
    )
 )

Comments

2 responses to “Rotation angle of MText using Lisp”

Kerry Brown

June 2, 2012

or with VLisp
(if (and (setq ent (vlax-ename->vla-object (car (entsel)))) (vlax-property-available-p ent 'Rotation) ) (/ (* (vla-get-rotation ent) 180.0) pi) )
(though the elegance is sort of spoiled by the lack of formatting on the blog) :-)

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Balaji

June 3, 2012

Thanks for sharing the vla method to the do the same.
I am sure, this will help the readers of this blog post.

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Rotation angle of MText using Lisp

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Rotation angle of MText using Lisp

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