[OpenSCAD] I have a suggestion: shell()...

M.Rule mrule7404 at gmail.com
Wed Aug 10 14:44:52 CEST 2011


There is a complication with using offset that I've run into.

If the wall is too thick, and the features curve too sharply, the
surface defined by the offset normals has self intersections.

The convolution idea sounds like it would work around this.


On Wed, Aug 10, 2011 at 8:34 AM, Giles Bathgate
<giles.bathgate at gmail.com> wrote:
> On 10 August 2011 13:22, nop head <nop.head at gmail.com> wrote:
>> Shell is the name of the operation in CAD systems and it must work by moving
>> faces inwards along the normals to make a smaller object that is then
>> subtracted. In CoCreate you also get an option to nominate a face to leave
>> open.
>
> Sorry, yeah I don't dispute that there should be module called 'shell'
> I was just thinking out loud as to how it might work using a more
> primitive but equally useful module. Once you have an offset module
> you should be able to define shell in terms of difference and offset
> e.g.:
>
> module shell(thickness) {
>   difference(){
>     child(0);
>     offset(-thickness) child(0);
>   }
> }
>
> ...of course it may as well be a built-in. What I wanted to say is
> that I can see a lot of uses for an offset module, and that shell can
> easily be implemented on top of that.
>
> Regards
>
> Giles
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