Problems with a linear extrude of a hull of four squares minus a circle
I have some simple code that worked with older versions of OpenSCAD but
doesn't work with OpenSCAD 2021.10.19.ci9029. I can't test later versions
because they don't run on Win7.
It uses a lot of library code but I can take the CSG that produces nothing
on the snapshot and paste it into an older version and it works.
This is the CSG:
color([0.745098, 0.647059, 0.529412, 1]) {
linear_extrude(height = 18, center = true, $fn = 0, $fa = 6, $fs = 0.25) {
group() {
group() {
group();
difference() {
group() {
group();
hull() {
multmatrix([[1, 0, 0, -150], [0, 1, 0, 304], [0, 0, 1, 0],
[0, 0, 0, 1]]) {
group() {
group() {
group() {
multmatrix([[1, 0, 0, 0.5], [0, 1, 0, -0.5], [0, 0,
1, 0], [0, 0, 0, 1]]) {
square(size = [1, 1], center = true);
}
}
}
}
}
multmatrix([[1, 0, 0, 150], [0, 1, 0, 304], [0, 0, 1, 0], [0,
0, 0, 1]]) {
multmatrix([[0, 1, 0, 0], [-1, 0, 0, 0], [0, 0, 1, 0], [0,
0, 0, 1]]) {
group() {
group() {
group() {
multmatrix([[1, 0, 0, 0.5], [0, 1, 0, -0.5], [0, 0,
1, 0], [0, 0, 0, 1]]) {
square(size = [1, 1], center = true);
}
}
}
}
}
}
multmatrix([[1, 0, 0, 150], [0, 1, 0, -304], [0, 0, 1, 0],
[0, 0, 0, 1]]) {
multmatrix([[-1, 0, 0, 0], [0, -1, 0, 0], [0, 0, 1, 0], [0,
0, 0, 1]]) {
group() {
group() {
group() {
multmatrix([[1, 0, 0, 0.5], [0, 1, 0, -0.5], [0, 0,
1, 0], [0, 0, 0, 1]]) {
square(size = [1, 1], center = true);
}
}
}
}
}
}
multmatrix([[1, 0, 0, -150], [0, 1, 0, -304], [0, 0, 1, 0],
[0, 0, 0, 1]]) {
multmatrix([[0, -1, 0, 0], [1, 0, 0, 0], [0, 0, 1, 0], [0,
0, 0, 1]]) {
group() {
group() {
group() {
multmatrix([[1, 0, 0, 0.5], [0, 1, 0, -0.5], [0, 0,
1, 0], [0, 0, 0, 1]]) {
square(size = [1, 1], center = true);
}
}
}
}
}
}
}
}
group() {
group() {
multmatrix([[1, 0, 0, -70], [0, 1, 0, -177.1], [0, 0, 1, 0],
[0, 0, 0, 1]]) {
group() {
group() {
group() {
group() {
circle($fn = 0, $fa = 6, $fs = 0.25, r = 38.0521);
}
}
}
}
}
}
}
}
}
}
}
}
It should produce this:
[image: image.png]
The 2D version looks correct but disappears when extruded. The sheet is
made by my sheet_2D()
https://github.com/nophead/NopSCADlib/blob/master/vitamins/sheet.scad#L61
module that makes sheets with square, rounded or chamfered corners. It only
fails when the corners are square, and it only fails when a hole is cut out
of it. So it seems to be a combination of difference, hull and linear
extrude.
The source that makes the 2D version of each side looks like this:
module side(side) {
dxf(side > 0 ? "rhs" : "lhs");
difference() {
sheet_2D(sheet, side_depth, side_height);
//square([side_depth, side_height], center = true);
if(extraction)
if(side > 0)
translate([extractor_pos.y - (depth / 2 - side_depth / 2),
-side_height / 2 + extractor_pos.z, 0]) {
drill(33 / 2, h = 0);
rotate(90)
extractor_screw_positions(false)
drill(screw_clearance_radius(M3_cap_screw), h
= 0);
}
else
translate([extractor_pos.y - (depth / 2 - side_depth / 2),
-side_height / 2 + inlet_z, 0])
drill(inlet_r, h = 0);
}
}
If I replace sheet_2D with a square it works, or if I have minute radii or
chamfers it works. It also works if I comment out the holes for one side or
the other. It only fails when both sides have holes, so I think it might be
something to do with if and groups() inside difference().
If somebody can test it with a later snapshot I will post a bug report if
it is still broken.
Works for me with 2022.02.23 on Windows 10.
Thanks. Perhaps it is a bug that is already fixed.
On Thu, 24 Feb 2022 at 15:40, Jordan Brown openscad@jordan.maileater.net
wrote:
Works for me with 2022.02.23 on Windows 10.