I am having a look at Minkowski and observe that the documentation isn't

all that clear on this question. The manual mentions this example

$fn=50;

minkowski()

{

cube([10,10,1]);

cylinder(r=2,h=1);

}

Which appears to demonstrate Minkowski working on 3d objects. However,

if you try

$fn=50;

minkowski()

{

translate([0,0,10])cube([10,10,1]);

cylinder(r=2,h=1);

}

... all you get is the same result translated upwards. The exact same

thing happens if you translate the cylinder instead of the cube, which

means this isn't really working in 3d.

If you try

$fn=50;

minkowski()

{

translate([0,0,-10]) cube([10,10,1]);

translate([0,0,10]) cylinder(r=2,h=1);

}

You are back to the original result. The two translations cancel each

other out!

But then, if you try

$fn=50;

minkowski()

{

translate([0,0,-10]) cube([10,10,1]);

translate([0,0,10]) cylinder(r=2,h=1);

}

you get something that looks more like an odd 3d hull operation.

Finally, some creative stuff to possibly igure out what is happening:

$fn=50;

minkowski()

{

cube([10,10,0.000000001]);

rotate([90,0,0])

difference() {

cylinder(r=2,h=1);

translate([1,0,0])cylinder(r=1.5,h=3,center=true);

}

}

It looks like the second object is now swept along the edge of the first

object, and the area between is almost like a hull. However, if you

switch the order, the result is the same...

Is there a more detailed description somewhere on how this really works?

Are these examples well defined?

Carsten Arnholm

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