OpenSCAD ERROR: Current top level object is not a 2D object

Question

I have created a Mengersponge in OpenScad which is a 3D object. I wanted to get an SVG export from it for the laser cutter but I receive this error:"Current top level object is not a 2D object." How do I select each side of this sponge to export it as SVG for laser cutting?

Code:

module MengerSponge(side = 270, order =3){
    difference(){
        cube([side,side,side],center=true);
        MengerSponge_aux1(side, order);
    }
    }
module MengerSponge_aux1(side, order){
    rotations=[
    [90,0,0],
    [0,90,0],
    [0,0,90],
    ];
    for(rotation=rotations){
        rotate(rotation)
    MengerSponge_aux2(side, order);
        }
}


 module MengerSponge_aux2(side, order){
     if(order>0){
        translate([0,-(side-(side/pow(3,order-1)))/2,0])
            for(i=[0:pow(3,order-1)-1]){
                translate([0,(side/pow(3,order-1))*i,0])
                    translate([-(side-(side/pow(3,order-1)))/2,0,0])
                        for(i=[0:pow(3,order-1)-1]){
                            translate([(side/pow(3,order-1))*i,0,0])
                                cube([(side/pow(3,order)),(side/pow(3,order)),side+1],center=true);
            }
        }
        MengerSponge_aux2(side, order-1);
     }
     else{
         echo("Fail");
     }
 }
side=270;
order=3;
MengerSponge(side, order);

```

fred_dot_u · Accepted Answer · 2022-11-09T16:45:41.850

5

Use the projection() feature of OpenSCAD to effectively generate a plane cut. Position the cube structure in such a manner that the x/y plane intersects the desired shape to be exported. Rendering the code will then generate a 2D image. Previewing the code will generate a 1 mm thick 3D model which will "flatten" when rendered.

For the image below, I did not translate the cube, merely placed the cube generation within the projection feature.

projection(){
MengerSponge(side, order);
}

This rendering will export to SVG as desired. Different positioning of the cube (rotate, translate) will create different patterns.

edited Nov 09 '22 at 16:45

answered Nov 09 '22 at 16:37

fred_dot_u

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Don't forget [`cut=true`](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/3D_to_2D_Projection) – R.. GitHub STOP HELPING ICE Nov 09 '22 at 19:01
I did forget that, yet the result is "acceptable," yes? What is the failure mode of forgetting it? – fred_dot_u Nov 09 '22 at 21:43
Without `cut=true`, you get a 2D shadow of the part, not a 2D cut (union of all cuts as Z ranges over -infinity to infinity). – R.. GitHub STOP HELPING ICE Nov 09 '22 at 22:27
That's useful information. Is there a link to an example model in which both circumstances are provided? – fred_dot_u Nov 09 '22 at 22:54
In tthe manual I linked to, no? – R.. GitHub STOP HELPING ICE Nov 10 '22 at 00:06

OpenSCAD ERROR: Current top level object is not a 2D object

1 Answers1