Orientation of faces w/ rotate_extrude() and cylinder()

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Orientation of faces w/ rotate_extrude() and cylinder()

Peter Falke
Hi all,

I noticed a difference in the orientation of the faces then I create things with rotate_extrude and cylinder.
I use both methods mixed together.
When I set fn to high numbers it makes almost no difference but with small numbers it is inconvenient.

The solution seems to rotate the rotate_extrude() by -90 degree:

In the picture below the yellow row was created with cylinder(...,$fn=i), the red row was created with rotate_extrude(...,$fn=i), and finally in the cyan row rotate(-90,zaxis)rotate_extrude(...,$fn=i):

Inline images 1


Could this be corrected directly in the code of OpenSCAD?


Regard,

TakeItAndRun


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Correct Rotation of rotate_extrude.scad (790 bytes) Download Attachment
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Re: Orientation of faces w/ rotate_extrude() and cylinder()

Giles Bathgate-2
Peter,

I've always thought rotate_extrude was a bit inconsistent with linear_extrude in the way that 2D shapes for
linear_extrude are in the x,y plane whereas 2D shapes for rotate_extrude are in the z,y plane, and as you rightly
point out rotations start at a different angle than the cylinder module.

Anyway It could be corrected in the code, but then it would break every ones designs. 
but perhaps  someone already thought of adding a

requires > 2012.07.06

declaration that can be placed at the top of the .scad script?

Regards

Giles

On 6 July 2012 19:19, Peter Falke <[hidden email]> wrote:
Hi all,

I noticed a difference in the orientation of the faces then I create things with rotate_extrude and cylinder.
I use both methods mixed together.
When I set fn to high numbers it makes almost no difference but with small numbers it is inconvenient.

The solution seems to rotate the rotate_extrude() by -90 degree:

In the picture below the yellow row was created with cylinder(...,$fn=i), the red row was created with rotate_extrude(...,$fn=i), and finally in the cyan row rotate(-90,zaxis)rotate_extrude(...,$fn=i):

Inline images 1


Could this be corrected directly in the code of OpenSCAD?


Regard,

TakeItAndRun


--
[hidden email]

P.S. Falls meine E-Mail kürzer ausfällt als Dir angenehm ist:
Ich probiere gerade aus kurze Antworten statt gar keine Antworten zu schreiben.
Wenn Du gerne mehr lesen möchtest, dann lass es mich bitte wissen.

P.S. In case my e-mail is shorter than you enjoy:
I am currently trying short replies instead of no replies at all.
Please let me know, if you like to read more.

Enjoy!


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Re: Orientation of faces w/ rotate_extrude() and cylinder()

kintel
Administrator
In reply to this post by Peter Falke
Hi Peter,

Unfortunately, this wasn't really thought through when designing those modules.
I tried to tweak the cylinder code a while back but, as Giles pointed out, it turned out that there are too many designs out there depending on the existing behavior.

Adding a compatibility option could make sense, but I'm uncertain if the benefit would outweigh the confusion.
Perhaps the best way is a clean break someday, clean up everything properly, and add a compatibility mode/converter to upgrade old files.

 -Marius