[BUG] round3d() in combination with any form of transform along Y

[yahbluez]

round3d() acts wrong full if combined with translations.

This cide snip shows the effect:

round3d(or=2) fwd(20) cube([20, 100, 10], );
up(10) cuboid([20, 100, 10]);

expected is that booth cubes have the same size,
but the rounded one is shorter by the amount the cube is moved.

Used the nightly openscad snap and cloned the BOSL2 today to ensure the bug is i the newest version.

[amatulic]

The fwd() isn't relevant. round3d() still truncates the cube without it. Here are two identical cubes overlaid, one rounded, one not.

include<BOSL2/std.scad>
round3d(or=2) cube([20,100,10]);
#cube([20,100,10]);

The rounded cube has length 50 regardless of how the original cube's y dimension is set.

It works only as long as the y dimension is less than 50. It seems like a hard-coded limit somewhere but I haven't looked at the code yet.

[yahbluez]

Thank you @amatulic that's one step more to get that fixed.

[amatulic]

It turns out all dimensions get truncated. Investigating further....

If you set the parameter size=300 in your call to round3d(), your example works. Basically set size to more than double the amount your object extends from any axis. This isn't documented.

round3d() is in miscellaneous.scad. It's a small module that simply calls offset3d() (in the same file) three times in a nested fashion. round3d() has a default parameter size=100, which gets passed to offset3d(), and this is the culprit. The size parameter is used in a difference() operation with a centered cube, which would explain why a non-centered cube truncates at 50, because a size 100 centered cube extends only out to 50 on each axis.

I note the documentation says:

This is an extremely slow operation. I cannot emphasize enough just how slow it is. It uses minkowski() multiple times. Use this as a last resort. This is so slow that no example images will be rendered.

Based on that, I suspect it wasn't tested extensively either.

It probably wouldn't hurt to make the default size something bigger, like 1000. The parameter is documented in offset3d(), so maybe the best solution is to add that documentation to round3d() also. But even the documentation in offset3d() should change, because it says size is the maximum size of the object to be rounded, when actually it is the maximum distance from the origin of the farthest point of the object to be rounded.

Because I didn't write this (I started looking closer into BOSL2 only a couple months ago) I defer to @adrianVmariano or @revarbat to recommend how this should be fixed, but for now you know how to solve it.

[yahbluez]

@amatulic

Thank you again, i did a work around for the model i was working on.

To put some shame on me, i did not do a "Go to definition" in code.
If i had done so i would have seen the size parameter in the first line of the definition.

That teaches me to look into modules that bother.

That is what i made today:

https://makerworld.com/en/models/1026215#profileId-1008411