Hi, I made an object, and then wanted to see what happened if I did a
Minkowski sum of the object with a small sphere. Since Minkowski is like
black magic to me I just wanted to see what happened, hoping for the corners
of my object being rounded.

The result was crashing OpenSCAD most of the times, and the other times I
got lots of these errors:

CGAL error in CGALUtils::applyBinaryOperator union: CGAL ERROR: assertion
violation!
Expr: G.mark(v1,0)==G.mark(v2,0)&& G.mark(v1,1)==G.mark(v2,1)
File:
/data/OpenSCAD/libraries-mingw64-master/mxe-w64/usr/x86_64-w64-mingw32.static/include/CGAL/Nef_S2/SM_overlayer.h
Line: 287
CGAL error in CGALUtils::applyBinaryOperator union: CGAL ERROR: assertion
violation!
Expr: itl != it->second.end()
File:
/data/OpenSCAD/libraries-mingw64-master/mxe-w64/usr/x86_64-w64-mingw32.static/include/CGAL/Nef_3/SNC_external_structure.h
Line: 1102

The code used is:

depth=20;
height=43;
width=60;
outerhole=20;
innerhole=10;

minkowski() {
difference() {
cube([depth, width, height], center=true);
translate([0,0,height/10]) rotate([0,90, 0]) cylinder(d=outerhole,
h=depth*2, center=true);
translate([0, -width/2+(width/8.1), height/2.75]) cube([depth+1,
width/4, height/3], center=true);
translate([0, width/2-(width/8.1), height/2.75]) cube([depth+1,
width/4, height/3], center=true);
for (x = [-4,12])
for (y = [-22,22])
rotate([0,90,0]) translate([x,y,0]) cylinder(d=5.5,
h=depth+1, center=true);
translate([0,-width/2+8,0]) cylinder(d=6.6, h=height+1,
center=true);
mirror([0,1,0]) translate([0,-width/2+8,0]) cylinder(d=6.6,
h=height+1, center=true);
}
sphere(2);
}

Worth investigating? (Using 2014.12.18 on Win64 )

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You're lucky, it crashed OpenSCAD on my system. (OpenSCAD 2014.12.18, W7/64)

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When I do F5/F6 it just hangs. This is because minkowski is a really slow
module(). Setting $fn=3; gave me a result after a while.

version 2014.12.04 x64 windows

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Probably same as  issue 947 https://github.com/openscad/openscad/issues/947

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The TPP is no simple “trade agreement.”  Fight it! http://www.ourfairdeal.org/

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Strike that.

I'm not sure if minkowski is designed for something with a hole in it.

depth=20;
height=43;
width=60;
outerhole=20;
innerhole=10;

difference() {
    minkowski() 
    {
    cube([depth-4, width-4, height-4], center=true);
    sphere(2);
    }   
    translate([0,0,height/10]) rotate([0,90, 0]) 
        cylinder(d=outerhole, h=depth*2, center=true);
    translate([0, -width/2+(width/8.1), height/2.75]) 
        cube([depth+1, width/4, height/3], center=true);
    translate([0, width/2-(width/8.1), height/2.75]) 
        cube([depth+1, width/4, height/3], center=true);
    for (x = [-4,12])
        for (y = [-22,22])
            rotate([0,90,0]) translate([x,y,0]) cylinder(d=5.5,

h=depth+1, center=true);

    translate([0,-width/2+8,-0.5]) cylinder(d=6.6, h=height+1,

center=true);

    mirror([0,1,0]) translate([0,-width/2+8,-0.5]) cylinder(d=6.6,

h=height+1, center=true);
}

Doesn't round the cut-outs tho.

Unless specifically shown otherwise above, my contribution is in the Public Domain; To the extent possible under law, I have waived all copyright and related or neighbouring rights to this work. This work is published globally via the internet. :) Inclusion of works of previous authors is not included in the above.

The TPP is no simple “trade agreement.”  Fight it! http://www.ourfairdeal.org/

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Software should never crash, regardless of misuse.

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