topic Re: When 2d point equal 3d point? in Visual LISP, AutoLISP and General Customization Forum

When 2d point equal 3d point?

Kirillspec — Mon, 30 May 2022 12:17:10 GMT

I have a code in which first i get lwpolyline from drawing

(setq pl (entget (car (entsel)))

then i get endpoint of this lwpolyline

(setq plbbb (cdr (assoc 10 (reverse pl))))

then i have in my drawing block with insertion point at the end of my polyline, and i want to obtain a selection set with this block only

(setq ssblock (ssget "_X" (list (cons 10 plbbb) (cons 0 "INSERT"))))

The question is - why this ssget function is worked and gives me a selection set with this block although end point of lwpolyline is 2d (without z) and insertion point of block is 3d (with z = 0). ?

If i want compare endpoint of lwpolyline and insertion point of block, the =, eq and equal returns nil

Re: When 2d point equal 3d point?

TomBeauford — Mon, 30 May 2022 12:51:36 GMT

A lwpolyline has an Elevation value in properties. It's constant for every vertex lwpolyline unlike a 3dpolyline but it has Elevation.

Re: When 2d point equal 3d point?

Kirillspec — Mon, 30 May 2022 13:04:41 GMT

Yes, but the question is why filter (cons 10 plbbb) where plbbb has only x and y coordinates works for block with insertion point which has x,y and z coordinates?

Re: When 2d point equal 3d point?

ВeekeeCZ — Mon, 30 May 2022 15:10:51 GMT

I think that where the point definition is required and a 2D point is accepted, then it is implicitly assumed that the omitted Z is 0.

While we don't see into the ssget definition.... it could be similar as

(entmakex (list (cons 0 "CIRCLE") (cons 10 '(0 0)) (cons 40 4))))

Re: When 2d point equal 3d point?

Kirillspec — Mon, 30 May 2022 15:07:16 GMT

OK, Thank you!

Re: When 2d point equal 3d point?

Sea-Haven — Wed, 01 Jun 2022 03:48:47 GMT

If you want 1 block dont worry about "X", (ssget pt) I have found reliable