topic How would you generate this shape in 3D using Lisp ? in Visual LISP, AutoLISP and General Customization Forum

How would you generate this shape in 3D using Lisp ?

dany_rochefort — Fri, 08 Apr 2022 15:18:15 GMT

Hi guys, any idea on how to generate this type of shape in 3D using Lisp ? Idea being that the user would input a few parameters and the 3d shape would generate from those inputs.

I am not looking for this Lisp itself, just some general ideas as to ''how you would go about it'' ....

It's call a Continous Radial Pile or Circular Pile Arragement; used in bulk handling. Both end would need to be rounded as shown on the left hand side of the pile.

Thanks in advance for the ideas !

Re: How would you generate this shape in 3D using Lisp ?

Kent1Cooper — Fri, 08 Apr 2022 16:12:43 GMT

Two PLINE commands, one UCS command and one EXTRUDE command should do it.

Given a center point [white Point], and either a mid-line radius [inner grey Arc] and a width for the base, or inner and outer radii for the base [for the grey outline], a routine could calculate vertex locations to draw the through-the-quarter-widths magenta Polyline easily enough. Then with a tilt-up UCS based on an end of the center-line Arc, and given a height at the ridge, it could make the yellow triangle with its heel at the center point of one swung end.

Extruding that yellow triangle along that magenta Polyline as a Path gives this:

The quarter-widths route of the Polyline path is what achieves rounding of the ends.

[The grey parts in the first image are for illustration -- they would not need to be drawn as part of the routine, nor would the Point in the middle.]

The inner grey Arc here is 3/4 of a full circle -- presumably an amount of included arc would also be a parameter the User would specify.

Re: How would you generate this shape in 3D using Lisp ?

dany_rochefort — Fri, 08 Apr 2022 17:02:06 GMT

@Kent1Cooper , thank you very much ! That is genius...

Best Regards,

Re: How would you generate this shape in 3D using Lisp ?

Kent1Cooper — Fri, 08 Apr 2022 17:49:34 GMT

I don't know why it didn't occur to me to just use the outline of the base directly, with the tip of the yellow triangle on it, this way:

But for some reason, it says it can't Extrude that triangle in this situation. It's not that it doesn't touch the path -- INTersection Osnap says they touch. I tried it in both the WCS and the triangle's UCS. It's all accurately drawn with good Snap values. I couldn't say why the previous approach works but this doesn't, but as long as something does....

Re: How would you generate this shape in 3D using Lisp ?

dany_rochefort — Fri, 08 Apr 2022 18:11:51 GMT

I will check that out also... Thx!

Re: How would you generate this shape in 3D using Lisp ?

stevor — Fri, 08 Apr 2022 23:07:25 GMT

One way is to subtract an inverted cone from a larger upright cone,

then slice off a quadrat with a triangular prism, or equivalent,

then add an upright cone on the left end, which would show half.

Re: How would you generate this shape in 3D using Lisp ?

Sea-Haven — Sat, 09 Apr 2022 03:42:50 GMT

Hi Kent did you rotate3d the triangle ? All done in World.

It could be done as a lisp. RAD1 RAD2 Height.

Re: How would you generate this shape in 3D using Lisp ?

leeminardi — Sat, 09 Apr 2022 20:30:57 GMT

Here's another way to construct the solid given a closed 2D polyline. Use the Extrude command with the Taper option. It avoids the need to create the triangular cross section.

The following code will create the shape with a taper angle of 25°.

THE TOP VIEW MUST BE ACTIVE WHEN THE COMMAND IS GIVEN!

(defun c:test (/) ; creates a solid with tapered sides from a closed polyline. (setq ss (ssget)) (setq en (ssname ss 0)) (setq ed (entget en)) (setq p1 (cdr (assoc 10 ed))) (setq p2 (mapcar '+ p1 '(0 0 0.1))) (command "_extrude" en "" "T" 25.0 p2 "") )