Tapered Offset/Stretch closed polyline shape

[SLW210]

I'll see what this week brings for extra playtime.

[dexus]

I managed to get rid of the flickering but keeping snap enabled.

Here is the new version:

offset.lsp

 

Instead of hiding the polyline before doing the osnap, I now keep the polyline hidden and render it with grvecs instead. Therefore no snapping to itself and no more flickering! 

Edited 23 hours ago by dexus

[pkenewell]

@dexus Well done! This works very well!

 

Just a suggestion if you wish to add more to it. My code below is for incorporating Function keys during a grread loop would be a good addition. It doesn't support everything, like Snap, polar tracking, osnap tracking, but it does all the toggle modes. It can replace the return condition in your grread loop.

;|==============================================================================
  Function Name: (pjk-Grread-Fkeys <Character Code))
  Arguments:
             kcode = integer; The Character code from the second element in the return from GRREAD.
  Returns:
             T if ENTER or SPACEBAR is pressed, otherwise NIL
  Description:
     This function emulates the functions performed when a function key is selected
     within a GRREAD loop.

     Created by Phil Kenewell 2018
================================================================================|;
(defun pjk-Grread-Fkeys (kcode / acv ret)
   (setq acv (atof (substr (getvar "acadver") 1 4)))
   (cond
      ((= kcode 6) ;; F3
         ;; Faster more efficient way to toggle osmode. Thanks to Lee Mac for the idea.
         (princ
            (strcat "\n<Osnap "
               (if (>= (setvar "osmode" (boole 6 (getvar "osmode") 16384)) 16384) "off>" "on>")
            )
         )
      )
      ((= kcode 25) ;; F4
         (if (>= acv 18.1) ;; If AutoCAD 2011 or Higher
            (princ
               (strcat "\n<3DOsnap "
                 (if (= (logand (setvar "3dosmode" (boole 6 (getvar "3dosmode") 1)) 1) 1) "off>" "on>")
               )
            )
            (princ
               (strcat "\n<Tablet " 
                  (if (= (setvar "tabmode" (- 1 (getvar "tabmode"))) 1) "on>" "off>")
               )
            )
         )
      )
      ((= kcode 5) ;; F5
         (cond
           ((= (getvar "SNAPISOPAIR") 0)(setvar "SNAPISOPAIR" 1)(princ "\n<Isoplane Top>"))
           ((= (getvar "SNAPISOPAIR") 1)(setvar "SNAPISOPAIR" 2)(princ "\n<Isoplane Right>"))
           ((= (getvar "SNAPISOPAIR") 2)(setvar "SNAPISOPAIR" 0)(princ "\n<Isoplane Left>"))
         )
      )
      ((= kcode 4) ;; F6
         (if (>= acv 17.0) ;; If AutoCAD 2007 or Higher
            (princ
               (strcat "\n<Dynamic UCS "
                  (if (= (setvar "ucsdetect" (- 1 (getvar "ucsdetect"))) 1) "on>" "off>")
               )
            )
            (princ
               (strcat "\n<Coords "
                  (if (= (setvar "coords" (if (= (getvar "coords") 2) 0 2)) 2) "on>" "off>")
               )
            )
         )
      )
      ((= kcode 7) ;; F7
         (princ
            (strcat "\n<Grid "
               (if (= (setvar "gridmode" (- 1 (getvar "gridmode"))) 1) "on>" "off>")
            )
         )
      )
      ((= kcode 15) ;; F8
         (princ
            (strcat "\n<Ortho "
               (if (= (setvar "orthomode" (- 1 (getvar "orthomode"))) 1) "on>" "off>")
            )
         )
      )
      ((= kcode 2) ;; F9
         (princ
            (strcat "\n<Snap "
               (if (= (setvar "snapmode" (- 1 (getvar "snapmode"))) 1) "on>" "off>")
            )
         )
      )
      ((= kcode 21)  ;; F10
         (princ
            (strcat "\n<Polar "
               (if (= (logand (setvar "autosnap" (boole 6 (getvar "autosnap") 8)) 8) 8) "on>" "off>")
            )
         )
         (Princ "\nNOTE: Polar Tracking is not supported in this command.")
      )
      ((= kcode 151) ;; F11
         (princ
            (strcat "\n<Object Snap Tracking "
               (if (= (logand (setvar "autosnap" (boole 6 (getvar "autosnap") 16)) 16) 16) "on>" "off>")
            )
         )
         (Princ "\nNOTE: Object Snap Tracking is not supported in this command.")
      )
      ((= kcode 31) ;; F12
         (if (>= acv 16.2) ;; If AutoCAD 2006 or Higher
            (princ
               (strcat "\n<Dynamic Input "
                  (if (minusp (setvar "dynmode" (- (getvar "dynmode")))) "off>" "on>")
               )
            )
         )
      )
      ((vl-position kcode '(13 32)) ;; Enter or Spacebar
         (setq ret T)
      )
   )
   ret
) ;; End Function (pjk-Grread-Fkeys)

 

Edited 22 hours ago by pkenewell

[GLAVCVS]

5 hours ago, dexus said:

I managed to get rid of the flickering but keeping snap enabled.

Here is the new version:

offset.lsp 10.87 kB · 1 download

 

Instead of hiding the polyline before doing the osnap, I now keep the polyline hidden and render it with grvecs instead. Therefore no snapping to itself and no more flickering! 

This is much better.

 

After seeing your code, I think there's something I may have misunderstood or didn't consider important: the use of the chord as a control parameter. All along, I've been thinking that the main goal was to ensure the cursor was tangent to the curve at all times. But I see that using the chord is important.

Clearly, these types of tasks were never part of my CAD menu.
In any case, this forces me to change my approach somewhat: I'll try to make 'offsetea' versatile in this case.

[GLAVCVS]

Another necessary question: Does the original code work as expected when selecting an arc segment flanked by other arc segments?
Is it possible this isn't intended in the code?