Great work Torsten and 'crew'!

Harm Jeurink

Torsten Paul schreef op 2021-12-01 10:33:

Try Dec 3, increasing r to 160 x and y steps set to 1 and play a bit with
the alpha by increasing the fraction from abs(y)/9 to abs(y) over 18. and
jut for fun gave the cubes a spin with rotate([x,y,z].
The moire patterns are something else.

Still there's some mystery in this.  Visually, it would at first glance
just be a series of hoops along the x axis and another around the y axis.
by the visual effect of the intersection of the two sets of hoops makes
hoops at multiple angles., not just along the x and y axes.
Here's a truncated version that shows the "extra" hoops.

[image: df677ec7-33f5-44ec-af7f-c44cc78ca19c.png]
// nobodysaidyoucouldpublishmyemail@gmail.com
// sphere equation
// license: CC0 https://creativecommons.org/publicdomain/zero/1.0/
//
// xx + yy + zz = rr

r =160;
rs = r*r;

//difference(){
for (x = [-r : 1: r]) {
for (y = [-r : 1 : r]) {
z = pow(rr - (xx + y*y), 1/2);
if (is_num(z))
color([abs(y) * .5, abs(x)*1.2, abs(z)*1.3] / 255, alpha =
abs(y) / 18)
translate([x, y, z])
rotate([x,y,z]) cube(0.6);
}
}

//translate ([-160,-160,60]) cube([320,320,320]);}

Apart from the transparency along the y axis, there's a lot of what
appears like a moire pattern that shifts and changes as you zoom in or out,
or even just rotate the shape.  Are these apparent white areas a result of
the rendering engine, or would we see them if this were a real object?
[image: image.png]
-Pat

On Wed, Dec 1, 2021 at 4:34 AM Torsten Paul Torsten.Paul@gmx.de wrote:

On Fri, Dec 3, 2021 at 2:57 PM Patrick Callahan pat.callahan1@gmail.com
wrote:

we see them if this were a real object?

well the color() call does evaluate to white along the "equator" but if you
render, then the color is not executed and you can see for yourself.

Yes,  the alpha is what cause the whiteness.  You can make the band of
white wider by increasing the denominator in alpha=abs(y)/n.

I want to know more about the apparent light and dark bands of the moire
pattern.
So I stepped back a bit, removed the rotation, Obvious rings start to show
up zooming in and out with r=40, but they can be seen better with r=80.
Strange things start to happen when you zoom out to about z=400 directly
above the hemisphere.

[image: image.png]

This is reminiscent of some of what you see when you look at
tesselations on
https://en.wikipedia.org/wiki/List_of_Euclidean_uniform_tilings

scrolled out you see this which makes no sense at all:

[image: image.png]
What causes that pattern to emerge from a pattern of dots covering the
entire circle?  My guess is Cubes not rendered at all because they are
between pixels so the rendering engine just drops them.  Once a cube
touches a pixel, I think the whole thing is rendered as a dot.
Protected from SPAM with HelpNinja https://helpninja.com/unsub/

On Fri, Dec 3, 2021 at 6:33 PM David Phillip Oster <
davidphilliposter@gmail.com> wrote:

The latest Dec 8th gives me this remark :
403 Forbidden
nginx/1.4.6 (Ubuntu)

I have no idea how I can solve that from here.

Regards,

Harm Jeurink

Torsten Paul schreef op 2021-12-01 10:33:

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

Here too. There are no pictures either behind the door or on the popup. The
error occurs when trying to download the script.

Tried Chrome, Edge on Win10 and Firefox on Ubuntu.

On Wed, 8 Dec 2021 at 09:02, info@hjcreations.nl wrote: