[HN Gopher] Spirals, Snowflakes and Trees: Recursion in Pictures
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       Spirals, Snowflakes and Trees: Recursion in Pictures
        
       Author : nbaksalyar
       Score  : 63 points
       Date   : 2020-12-30 17:27 UTC (5 hours ago)
        
 (HTM) web link (learn.hfm.io)
 (TXT) w3m dump (learn.hfm.io)
        
       | babkayaga wrote:
       | i noticed a bunch if spirals demoed seem to kind of twinkle when
       | you scroll the page. is this a known optical illusion?
        
         | philo23 wrote:
         | A Moire pattern perhaps?
         | https://en.wikipedia.org/wiki/Moir%C3%A9_pattern
        
         | kroltan wrote:
         | It's called "limitations of display devices"!
         | 
         | The high contrast of the pictures, modern smooth scrolling,
         | reveals the inherent ghosting (or overdrive) of most computer
         | screens. While decent monitors are usually not noticeable in
         | more regular use-cases, tightly-packed lines are very
         | noticeable.
         | 
         | That means that there is a partially-faded copy of the previous
         | frame still visible for a fraction of a second, which your eye
         | sees, and the resulting image has Moire fringes because of the
         | mismatching angles.
         | 
         | For example, my monitor shows the purple drawings pretty
         | sharply, but the green or white pictures are very artifacted
         | when moving.
        
           | jeremy_wiebe wrote:
           | Is it not due to the inexactness of mapping the image pixels
           | to device pixels? (Similar to what happens when drawing text
           | with antialiasing)?
        
             | kroltan wrote:
             | In principle it could be, but usually browsers snap element
             | rectangles to the pixel, thus protecting against that (have
             | you ever seen a blurry border on a box because its contents
             | had 0.5px size? nope, even though it is annoyingly common
             | in things such as game UIs)
             | 
             | Plus you can see the same effect on the UFO tests, which
             | strictly uses integer positions so pixel misalignment is
             | not a factor.
        
           | kroltan wrote:
           | (me again)
           | 
           | Which reminds me of this neat site to visualize these
           | limitations: https://www.testufo.com/ghosting
           | 
           | On the top-right there is a drop-down, try all the options in
           | the "Tests" category! Note it has fast-moving imagery that
           | might trigger epilepsy if you're particularly sensitive.
        
       | ericslandry wrote:
       | Reminds me of https://mitpress.mit.edu/books/computational-
       | beauty-nature
        
       | nayuki wrote:
       | The lack of whitespace on the left and right sides of the page is
       | jarring.
        
         | nbaksalyar wrote:
         | Here's a better link: http://learn.hfm.io/fractals.html (can't
         | edit it anymore, sorry)
        
           | dang wrote:
           | Changed from http://learn.hfm.io/fractals/fractals.html.
           | Thanks!
        
       | 2xmm wrote:
       | If you like playing around with fractals, you'll love playing
       | around with images generated by context free grammars:
       | https://www.contextfreeart.org
        
       | jpcooper wrote:
       | Lots of ways of generating fun pictures in A New Kind of Science
       | (https://www.wolframscience.com/nks/) as well.
        
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       (page generated 2020-12-30 23:00 UTC)