another line-arc intersection question

I am sure its a simple fix I am not sure what I am doing wrong. I have searched the forum here and looked at lots of examples which is why I can not see what is wrong.

I have a line that intersects an arc, if the line is extended to meet the arc the simple lisp works if the line does not touch can not get it to work and not sure why not with extending entity.

(vl-load-com)
(setq obj1 (vlax-ename->vla-object (car(entsel "\nPick arc :"))))
(setq obj2 (vlax-ename->vla-object (car(entsel "\nPick line :"))))
(setq intpt (vlax-invoke obj1 'intersectWith obj2 1))   
; 1 is extend line acExtendthisentity
;(setq intpt (vlax-invoke obj1 'intersectWith obj2 acExtendnone)) 
; 0 is acExtendnone
(command "point" intpt)

(princ)

You are almost there, try updating

(setq intpt (vlax-invoke obj1 'intersectWith obj2 1))

to

(setq intpt (vlax-invoke obj2 'intersectWith obj1 acExtendThisEntity))

Found it need to use acExtendOtherEntity its always a simple answer but finding it can be hard sometimes in the help.

(setq intpt (vlax-invoke obj1 'intersectWith obj2 acExtendotherEntity))

also

(setq intpt (vlax-invoke obj1 'intersectWith obj2 2))

; 2 is acExtendotherEntity

; 3 is acExtendboth

Didn't think of using the acExtendOtherEntity in that context

May find it useful down the line

Thanks jammie getting the order of which one to extend makes the difference. Both ways work.

Just a little quirk need to watch out for osnaps can over-ride answer.

BigAl,

OSnaps won't affect the VL/Ent* methods, so I would advise to using something like:

(lambda (p) (entmakex (cons 0 "POINT") (cons 10 p)))

to create your point.

Another helpful thread here:

http://www.cadtutor.net/forum/showthread.php?t=44768

Curious,

Why use lambda here?

I wanted to show a general example (i.e. not make it specific to a variable), but didn't want to define a function to do it, - perhaps unnecessary, but the cat can be skinned in many ways

That make sense

How do you call on the expression to actually create the point?

Well, it is probably not practical in this example, but:

(  (lambda (p) (entmakex (cons 0 "POINT") (cons 10 p)))  intpt)

I was always under the impression that you could only call on lambda via one of the apply functions

Learn something new everyday

Thanks for that

No worries mate

You are almost there, try updating

 

(setq intpt (vlax-invoke obj1 'intersectWith obj2 1))

to

 

(setq intpt (vlax-invoke obj2 'intersectWith obj1 acExtendThisEntity))

Just for the record: (eq acExtendThisEntity 1) => T

FYI You also can check using:

(eval acExtendThisEntity)

FYI You also can check using:

 

(eval acExtendThisEntity)

or !acExtendThisEntity

I was trying to show that they were equal. I'm not sure why I showed it in code.