Circles do not exist

#1

Post by ingve » Tue, Sep 19, 2023, 7:44 PM UTC

Circles do not exist
nibblestew.blogspot.com

Re: Circles do not exist

#2

Post by wizofaus » Tue, Sep 19, 2023, 7:56 PM UTC

Doesn't PS have "arc"?

Re: Circles do not exist

#3

Post by proto_codex » Tue, Sep 19, 2023, 7:57 PM UTC

fact: circles are actually squares that have successfully deceived you. You have been bested by a shape.

Re: Circles do not exist

#4

Post by accrual » Tue, Sep 19, 2023, 8:00 PM UTC

That's pretty interesting. I'll now be doubting every circle I walk by, questioning if it's even real or just some approximation.

Re: Circles do not exist

#5

Post by fooofw » Tue, Sep 19, 2023, 8:03 PM UTC

wizofaus wrote: post #2

Doesn't PS have "arc"?

I was curious, so I looked up arc in the PostScript Language Reference [1]. It contains the following (p. 530):

> The arc is represented internally by one or more cubic Bézier curves (see curveto) approximating the required shape. This is done with sufficient accuracy to produce a faithful rendition of the required arc. However, a program that reads the constructed path using pathforall will encounter curveto segments where arcs were specified originally.

[1] https://www.adobe.com/jp/print/postscript/pdfs/PLRM.pdf

Re: Circles do not exist

#6

Post by kanzenryu2 » Tue, Sep 19, 2023, 8:04 PM UTC

That's just a circular argument

Re: Circles do not exist

#7

Post by Puts » Tue, Sep 19, 2023, 8:05 PM UTC

"The only primitives they have are straight line segments, rectangles and Bézier curves. The only way to create a proper circle is to have a raster image like the one above."

Is this really an accurate conclusion? Just because there are no primitives for a circle – postscript is still a programming language so you can also plot a proper circle with trigonometry?

Re: Circles do not exist

#8

Post by hinkley » Tue, Sep 19, 2023, 8:05 PM UTC

proto_codex wrote: post #3

fact: circles are actually squares that have successfully deceived you. You have been bested by a shape.

So you're saying you don't have to square a circle because it already is?

Re: Circles do not exist

#9

Post by hinkley » Tue, Sep 19, 2023, 8:09 PM UTC

For 3d printing.

Lathes do circles all the time. But it would be difficult to rotate either the head or the bed around an arbitrary axis in order to print a proper circle.

Re: Circles do not exist

#10

Post by CharlesW » Tue, Sep 19, 2023, 8:11 PM UTC

Puts wrote: post #7

"The only primitives they have are straight line segments, rectangles and Bézier curves. The only way to create a proper circle is to have a raster image like the one above." Is this really an accurate conclusion? Just because there are no primitives for a circle – postscript is still a programming language so you can also plot a proper circle with trigonometry?

> Just because there are no primitives for a circle…

Is a 360° arc not a circle?

  %!PS
  /newpath
  100 100 50 0 360 arc
  stroke
  showpage