Help: Autolisp routine for measuring vertical distance from a point to a curve

[maikhanhmst]

Hi, 

I have a point on a horizontal line and want to measure distance from it to a curve. When I pick a point and a curve, the routine returns the linear distance between them. Could someone please tell me how to do it? 

Thanks in advace.

Khanh.

[pbejse · Accepted solution]

---

@maikhanhmst wrote:

Hi, 

I have a point on a horizontal line and want to measure distance from it to a curve. When I pick a point and a curve, the routine returns the linear distance between them. Could someone please tell me how to do it? 

Thanks in advace.

Khanh.

---

(defun c:demo (/ a b)
  (setq a (getpoint "\nPick point on Horizontal line \:"))
  (setq b (Car (entsel "\nSelect Curve Line:")))
  (alert
    (rtos (distance (osnap a "nea")
		    (vlax-curve-getClosestPointToProjection
		      b
		      (osnap a "nea")
		      '(0.0 1.0 0.0)
		    )
	  )
    )
  )
)

[maikhanhmst]

Hi,

Many thanks. That works exactly what I wanted. As a part of my learning AutoLisp, I wondered how (osnap a "nea")  work, so when I run your routine, I deleted the statements, but it run well. So what happen if I delete it. Could you mind helping me understand this?

Khanh.

[pbejse]

---

@maikhanhmst wrote:

Hi,

Many thanks. That works exactly what I wanted. As a part of my learning AutoLisp, I wondered how (osnap a "nea")  work, so when I run your routine, I deleted the statements, but it run well. So what happen if I delete it. Could you mind helping me understand this?

Khanh.

---

(osnap a "nea") ;<-- that line ensures the distance will be taken from a point touching the line object.

Now if during the prompt from pickpoint you already set a snap lets say "nea" or osmode set to 512 then the line above can be omitted. i meant just the a variable will be enough.

another way to write the code is

(defun c:demo (/ a b)
  (setq a (getpoint "\nPick point on Horizontal line :"))
  (setq b (CAr (nentselp a)));<-- select line via coordinates
  (setq c (Car (entsel "\nSelect Curve Line:")))
  (alert
    (rtos (distance (setq a (vlax-curve-getclosestpointto b a));<-point on the line  
                    (vlax-curve-getClosestPointToProjection
                      c
                      a
                      '(0.0 1.0 0.0)
                      )
                    )
          )
    )
  )

HTH

[maikhanhmst]

I got it. If the routine doesn't include (osnap a "nea") and the osmode isn't 512 or osnap "nea" setting not picked in the osnap box, the distance isn't taken correctly.

Thanks.