Bug while rendering a recursive construction

CONTENTS DELETED

Your polyhedron is partially inside out. Use F12 to check for purple triangles.
Another problem might be singularities where the polyhedrons meet. I used a scale(1.01) as workaround

This code works:

a= 10;
SOMMETS = [
            [0,0,a/sqrt(2)],
            [a/sqrt(2),0,0],
            [0,a/sqrt(2),0],
            [-a/sqrt(2),0,0],
            [0,-a/sqrt(2),0],
            [0,0,-a/sqrt(2)] ];

module octa() {
    scale(1.01)
    polyhedron(
        points = SOMMETS,
        faces = [ [1,0,2], [2,0,3], [3,0,4], [4,0,1], [5,1,2], [5,2,3], [5,3,4], [5,4,1] ]
        );
    }

module fractale(n) {
    if ( n == 0 )    {
        octa();   
    } else {  
       for (point = SOMMETS) { 
            fractale(n-1);
            translate(pow(2, n - 1)*[a/sqrt(2),a/sqrt(2),0]) fractale(n-1);
            translate(pow(2, n - 1)*[0,2*a/sqrt(2),0]) fractale(n-1);
            translate(pow(2, n - 1)*[-a/sqrt(2),a/sqrt(2),0]) fractale(n-1);
            // top
            translate(pow(2, n - 1)*[0,a/sqrt(2),a/sqrt(2)]) fractale(n-1);
            // bottom
            translate(pow(2, n - 1)*[0,a/sqrt(2),-a/sqrt(2)]) fractale(n-1);
       }
    }
}


fractale(2);

Great, thank you very much,
I'm still getting screwed with the faces...
Thanks!

The STL file needs to be repaired after pressing F7.
And the repair in 3D Builder removes "holes" in the fractal, that's not right.
The problem persists with "scale(1.xx)", I ask you again for help...
Thanks

Did you use my code? It defines the polyhedrons correctly and should let you export the stl (f7) after f6.

Yes.
No problem detected in OpenSCAD.
But :

OK, I had a quick check on your code and found out that there are even more singularities. I guess, because your polygon contains the origin, which is not affected by scale. After adding some small x-translations at least my slicer didn't complain any more.

a= 10;
SOMMETS = [
            [0,0,a/sqrt(2)],
            [a/sqrt(2),0,0],
            [0,a/sqrt(2),0],
            [-a/sqrt(2),0,0],
            [0,-a/sqrt(2),0],
            [0,0,-a/sqrt(2)] ];

module octa() {
    scale(1.01)
    polyhedron(
        points = SOMMETS,
        faces = [ [1,0,2], [2,0,3], [3,0,4], [4,0,1], [5,1,2], [5,2,3], [5,3,4], [5,4,1] ]
        );
    }

module fractale(n) {
    if ( n == 0 )    {
        octa();   
    } else {  
       for (point = SOMMETS) { 
            fractale(n-1);
            translate(pow(2, n - 1)*[a/sqrt(2),a/sqrt(2),0]) fractale(n-1);
            translate(pow(2, n - 1)*[0.01,2*a/sqrt(2),0]) fractale(n-1);
            translate(pow(2, n - 1)*[-a/sqrt(2),a/sqrt(2),0]) fractale(n-1);
            // top
            translate(pow(2, n - 1)*[0.01,a/sqrt(2),a/sqrt(2)]) fractale(n-1);
            // bottom
            translate(pow(2, n - 1)*[0.01,a/sqrt(2),-a/sqrt(2)]) fractale(n-1);
       }
    }
}


fractale(2);

Thank you very much.
I understood the modifications.
In fact, I had gotten around the problem by changing the definition of the octahedron, using two "cylinders" with 4 faces and a radius = 0 at the top vertex rather than by a polyhedron.