Hello, this is my first post here as I'm using OpenSCAD again after years.
I'm trying to code a 2 axis slicer and there is a step that seems
impossible to do, but maybe is it because I'm not aware enough of
functional programming techniques.

Here is what I do :

• I have a volume
• make several cuts along 1st axis (intersection of volume and a cube)
• make several cuts along 2nd axis (intersection ...)
• gather intersection of those cuts

Then, there is the step that I cannot do : access each of the gathered
intersections, and split each of them in half (top and bottom).

Next steps will be :

• subtract union of top halves to each cuts along 1st axis
• subtract union of bottom halves to each cuts along 2nd axis
• produce a projection of each cuts

This is something I'm doing with OpenJSCAD for years now and I needed to
write my own 3d split code to be able to do so. The main problem is that
sometimes an intersection returns two or more separated object into the
same geometry and my process need to split each of them separately in order
to make correct cross pieces.

Is it possible to split a geometry having separated objects so that each
can be processed separately ?

my code : (I need inter() to have several children instead of only 1)

w= 0.6;

inter();
translate([20,0,0])tranchesX();
translate([-20,0,0])tranchesY();
translate([0,0,30])volume();

module tranchesX() { for(i = [2:3:12])trancheX(i); }

module tranchesY() { for(i = [0:4:20-1])trancheY(i); }

module inter(){
intersection(){
union(){tranchesX();}
union(){tranchesY();}
}
}

module trancheY(dec) {
intersection() {
translate([-1, dec, -1])cube([14, w, 22]);
volume();
}
}

module trancheX(dec) {
intersection() {
translate([dec, -1, -1])cube([w, 12, 22]);
volume();
}
}

module volume() {
difference(){
cube([12,10,20]);
scale([1,2,1])translate([6,2.5,6])sphere(r=5);
}
}

As Carsten said, there's no way to "split" geometry.

If, for instance, you wanted to take a sphere, cut the top half from the
bottom half, and separate the two halves, the only way to do it is to
create two spheres, cut away the top half of one, and cut away the
bottom half of the other.

Now, because OpenSCAD is after all a programming environment, that
doesn't mean that you have to type out both models.

Start with this module:

big = 1000;
module cut(d) {
	// First:  top half
	translate([0,0,d/2]) intersection() {
		children();
		translate([-big,-big,0]) cube([big*2,big*2,big]);
	}

	// Second:  bottom half
	translate([0,0,-d/2]) intersection() {
		children();
		translate([-big,-big,-big]) cube([big*2,big*2,big]);
	}
}

and here's how you use it:

cut(10) sphere(10);

and here's what you get:

The same principle applies to any other kind of cut:  for each
"segment", generate the model and cut away what you don't want in that
segment.

I want to produce this kind of output :
http://forum.openscad.org/file/t3103/Capture_d%E2%80%99%C3%A9cran_de_2020-12-01_15-28-26.png

Making the x and y slices was easy, their intersection also. But then I was
unable to access those intersections one by one (because I need to split
each of them in one top half and one bottom half).
With OpenJSCAD I needed to write my own Split3d to split them, but such
function needs to read a polyhedron vertices and sort them and there's
nothing to do that in OpenSCAD.

here what I have for the moment :
http://forum.openscad.org/file/t3103/Capture_d%E2%80%99%C3%A9cran_de_2021-01-23_09-23-41.png

--
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Yes, it can be done by specifying manually each time an intersection contains
more than one piece, but it would make the script very unpractical as it is
intended to be used from customizer to create skeleton of whatever volume
the user want.

Here is the original OpenJSCAD script : see  here
https://raw.githubusercontent.com/gilboonet/gilboonet.github.io/master/sq_edit/slice_2axis_example.js
http://forum.openscad.org/file/t3103/Capture_d%E2%80%99%C3%A9cran_de_2021-01-24_13-13-26.png

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Here is a part of my process
http://forum.openscad.org/file/t3103/Capture_d%E2%80%99%C3%A9cran_de_2021-01-24_13-59-06.png
I design a volume (save it as 3d file)
Then make its skeleton, here with 3 X slices and 3 Y slices
The skeleton is made by interlocking those slices.
When an intersection returns more than one geometry, each of those
geometries must be considered as one intersection

The interlocking is made by splitting  each intersection in 2 (top and
bottom)
And subtract all top to X slices and all bottom to Y slices.
This way one's have slices that interlock perfectly

I'm making a collection of designs to be built from cardboard and I'm using
part vanilla js and jscad 2 scripts to generate my plans. I was wondering
whether it could be possible to do the same with OpenSCAD.

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