Hi, the latest OpenSCAD version produces the warning above, for example when running the list-comprehension-demos/toothed-belt.scad

I thought that to be be trivially fixable, but I have found the following behavior hard to grasp:

vec_is_undef([1,2,3,undef], index_=3) == true
vec_is_undef([1,2,3,undef,4], index_=3) == false

What is the rationale behind that? Do we actually need it?

Example producing emptiness:

rounding(r=1) shell(d=-1) square(10);

I'm trying to use the scad-utils as described by mathgrl at https://mathgrrl.com/hacktastic/2018/11/knots-in-openscad-with-sweeper/

use <sweep.scad>
use <scad-utils/shapes.scad>

function f(a,b,t) = // rolling knot
[ a * cos (3 * t) / (1 - b* sin (2 t)),
a * sin( 3 * t) / (1 - b sin (2 t)),
1.8 * b * cos (2 * t) /(1 - b sin (2 *t))
];

a = 0.8;
b = sqrt (1 - a * a);

function shape() = circle(60, $fn=48);

step = 0.005;
path = [for (t=[0:step:1-step]) 200 * f(a,b,t*360)];
path_transforms = construct_transform_path(path);
sweep(shape(), path_transforms, true);

Lots of the code in sweeper seems to rely on scad-utils and includes something called shapes.scad from there.

Anyone know where to find that as its no longer here it seems ?

Sorry if this is a dull question

All help much appreciated.

The library has lots of nice code which is generally useful, but without a clear license, it's basically not possible to distribute the code along with OpenSCAD or as separate package in Linux distributions. I hope you would like to see it included / distributed, so please add a license to make it possible.

Hi, I found this example from 2014 which looks like something I've been after, except there is an 'r' parameter in linear_extrude which gets thrown up as a warning as it doesn't exist. Images of the example rendered from here: http://forum.openscad.org/Experiment-with-rounded-extrusions-td7928.html and my render which has only half of the round edges. Can anyone explain where the 'r' parameter in linear_extrude might be found?

use <scad-utils/morphology.scad>
eps = 0.01;

$fn=64;

module base() {
union() {
rounding(2) fillet(2) difference() {
square([50,40]);
translate([(50-25)/2,40-15]) square([25,20]);
}
rounding(0.25) square([50,10]);
}
}

difference() {
linear_extrude(height=10,r=0.25,convexity=3)
base();

    translate([0,0,-eps]) linear_extrude(height=10 + 2*eps,r=-1,convexity=3)
            translate([(50-30)/2,5])
                    rounding(2) square([30,15]);

    rotate([90,0,0])
            translate([5,2.5,-1])
                            linear_extrude(height=1+eps,r=[0.25,-0.25])  
                                    rounding(1) square([40,5]);

}

for (x = [6.25, 50-6.25])
translate([x, 40-6.25, 10])

            linear_extrude(height=5,r=[-.25,.25],chamfer=[0,1])
                    circle(r=2);

Sorry, maybe I'm a dump guy.. please can you help me:
There is a Readme.md and there are the files. But there is almost NO connection between the two.
Readme shows a lot examples with "shape", but there is no "shape" in the files. And all the other files (except mirror) are not mentioned in the readme..? How can I use it (of course I can read the scad files and experiment, but is that expected)?

This module seems to be what I'm looking for but I don't quite grasp how to control it. Is there some documentation about it?

It appears that pull request #1 should have included the lists.scad file as well, as it adds the remove() function that is required by the spline() function.

is this supposed to work ?

use <scad-utils/transformations.scad>
use <scad-utils/shapes.scad>
use <scad-utils/hull.scad>
use <list-comprehension-demos\skin.scad>

fn=32;
$fn=60;

r1 = 25;
r2 = 10;
R = 40;
th = 2;

function rhull(r)=[for(i=hull(r))r[i]];

module tube()
{

    difference()
    {
        skin([for(i=[0:fn])
              transform(
                rotation([0,180/fn*i,0])*translation([-R,0,0]), 
                rhull(concat(circle(r1+(r1-r2)/fn*i),square((r1+2.5*r1/2))))
        )
        ]);

//        echo( concat(circle(r1+(r1-r2)/2),square((r1+r2)*2)));
//        echo(rhull(concat(circle(r1+(r1-r2)/2),square((r1+r2)*2))));

        r1 = r1-th;
        r2 = r2-th;
        skin([for(i=[0:fn]) 
              transform(rotation([0,180/fn*i,0])*translation([-R,0,0]), 
                        circle(r1+(r1-r2)/fn*i))]);
    }
}

tube();

modified from here:
http://stackoverflow.com/questions/28842419/linear-rotational-extrude-at-the-same-time

In shapes.scad, the winding order of the shapes are inconsistent.

• square(): clockwise
• circle(): anti-clockwise
• regular(): anti-clockwise (as it uses circle())
• rectangle_profile(): anti-clockwise

This causes trouble when sweep()-ing (as in https://github.com/openscad/list-comprehension-demos/blob/master/sweep.scad) circle(), as the normals of the resulting polygon end up pointing inwards instead of outwards.

It would probably make sense to make all of the shapes have anti-clockwise winding order, to match the OpenSCAD polyhedron expectations.

(btw, I'm happy to submit a pull request to fix it if you agree)

Hi Oskar,

I don't remember when exactly cross() was added into OpenSCAD - it's been several years since my initial add of linear algebra support and Marius' full re-write - but it makes this (re)definition obsolete:

See docs: https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/The_OpenSCAD_Language#cross

Andrew.