polyhedron in openSCAD yields "No top level geometry to render" - openscad

Question

I do not get why this polyhedron gives me a "no top level geometry to render" error. All triangles are correctly oriented, "thrown-together"-view shows only yellow outside faces. This is my code:
top_width=39;
bottom_width=51;
col_offset=6;
length=160;
height=40;
rows=10;
cols=40;
top_row_width=top_width/rows;
bottom_row_width=bottom_width/rows;
col_length=length/cols;
walls=0.4;
box();
module box(){
polyhedron(
points=[
[ // point 0
0,
0,
height
],[ // point 1
length,
0,
height
],[ // point
length,
top_width,
height
],[ // point 3
0,
top_width,
height
],[ // point 4
0,
0+col_offset,
0
],[ // point 5
length,
0+col_offset,
0
],[ // point 6
length,
bottom_width+col_offset,
0
],[ // 7
0,
bottom_width+col_offset,
0
]
],
triangles=[
[3,1,0],
[3,2,1],
[4,5,6],
[4,6,7],
[7,2,3],
[6,2,7],
[4,3,0],
[4,7,3],
[1,2,5],
[1,2,5],
[2,6,5],
[0,1,5],
[0,5,4]
]
);
}
Any hint is very appreciated, thanks in advance!

Answer 1

Well I'm baffled too. Latest version of OpenSCAD supports faces in place of triangles:
faces = [
[0,3,2,1],
[0,1,5,4],
[1,2,6,5],
[2,3,7,6],
[0,4,7,3],
[4,5,6,7] ]
and that renders OK.
You might try asking on the OpenSCAD forum http://forum.openscad.org/ which is more active than here.