Was able to use Flow to project a one turn helix onto an extruded rounded rectangle,
without squiggly lines.

The object to flow is the helix.
The base surface is a cylinder extruded from a circle.
The target is the extruded rounded rectangle, the same height as the cylinder.

The circumference of the circle DOES NOT need to equal the perimeter of the rounded square.

The radius of the helix must equal the radius of the circle.

Swept a small rectangle to represent the wire.




Can this be Generalized to make a radial projection command?

Hi Brian, re: radial projection method, what about the "fin construction" method as shown by Danny here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=4084.3
http://moi3d.com/forum/index.php?webtag=MOI&msg=3530.2

That's where you sweep a line along your helix (with Twist : flat option set) to build the fin surface and then use Construct > Curve > Isect to generate an intersection curve between the fin and the rounded rectangle.

Although I guess now that I try that it's maybe not what you want, the intersection along the longer sides will be a little wavy since the object does not have radial symmetry.

So possibly an exact radial projection is not really what you want here?

- Michael

Thank you Michael.
Did the "fin construction" method yesterday, and the long sides were a bit wiggly.
I'll have to try it with a different helix radius...maybe there is one which will "match"?

The flow method seemed to yield straight sides, not sure about the corner radius.

Hi Brian, I think the fin method is equivalent to a "radial projection", but a radial type projection probably isn't what you really want. With a radial projection things that are further away from the radial axis are traversing a longer distance than things close to the radial axis, and so on a shape like your rounded rectangle that is not symmetrical around the axis and has some portions further away and some closer to the radial axis it will yield that curved result that you don't want.

Flow is probably more what you want, since that can map an elevation onto a path just based on distance traveled along the path.

- Michael

Thank you for the explainations and clarifications.

"based on distance traveled along the path" makes sense.

So in Flow, the cylindrical (extruded_circle) base surface maps onto the rounded square extrused target surface, for the distance traveled, scaling up or down as
needed, causing a similar scaling of the helix...

Got to try some different target surfaces...

Hi Brian, actually I had thought that you were using curve-to-curve flow.

Surface to surface flow is done by mapping "position in UV space" from one surface to another, it does not necessarily map from distance to distance because UV space is not necessarily uniformly distributed, a squishy surface can be narrow across in one area but wider in a different area of the same surface.

If you are dealing with extrusions then that's a particular case where they are uniform, but also if you're dealing with extrusions using curve-to-curve flow should just be easier in general.

Check out here for an example of using curve-to-curve flow for this sort of "height mapping" from one 2D profile onto a bendy curve:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4785.13


Or here's another example - here is an angled line with a base line under neath it:



Select that angled line, it's the one you want to remap onto the bendy curve. Run Transform > Deform > Flow, select the base line underneath it as the base curve, and the bendy curve as the target curve and then you'll get a result like this:




Initially the curve will occupy the same length of the target curve as the length of the base line. You can enable the "Stretch" option (which I did here) to make the result stretch across the full length of the target curve.

But curve to curve flow works by traveling across curves by distance traveled along the curve, surface-to-surface flow uses the UV parameter space of the surface which can be compressed or expanded in different zones of the surface and so if you want to do stuff that maintains distances the curve-to-curve flow may be better.

- Michael

Here's another example - basically any pattern that is easy to draw in 2D can be put onto a curve this way. Just an angled line will work for a ramp like result that just gains height as it marches along the curve but other patterns like this will work with the same thing as well:





- Michael

Thank you Michael.
Using curve to curve flow is much easier.

Having trouble with flow getting the start of the square helix to begin at the beginning of
the red helix. Tried rotating the circle multiple times to adjust the start position.

Is there a script to find the start of a circle, other than by extruding it ? :-)

Also for several days, when typing these forum messages, my arrow keys do not cause a visible movement
of the vertical bar cursor. The arrow keys do cause the cursor to move, invisibly. The cursor does not show up in its
correct position until another character is typed. ?

(The arrow keys work fine in notepad or onenote)

Hi Brian,

> Is there a script to find the start of a circle, other than by extruding it ? :-)

Check out the attached plug-in "MarkCurveStart" - it will place a point object onto the start location of any curve.


> Also for several days, when typing these forum messages, my arrow keys
> do not cause a visible movement of the vertical bar cursor. The arrow keys
> do cause the cursor to move, invisibly. The cursor does not show up in its
> correct position until another character is typed. ?

That sounds kind of weird - probably some kind of bug in your web browser, what web browser are you using and does it go away if you update to the most current version?

- Michael

That is a handy plugin thanks.

Peace,
Rich_Art. ;-)

Thank you again Michael for another great script.

For the problem with the arrow keys, (under Internet Explorer 9, which worked fine for many months), this message is being done with google chrome,
and there is no such problem now. Weird.

This edit back with IE9, arrow keys do not work properly. So which web browser is recommended?

Edit #2: Just now, running IE9 with "No Add-Ons" mode, and the arrow keys are working fine.

Hi Brian, so it sounds like some misbehaving IE9 add-on was messing up the arrow keys. It's probably not bad to just disable them all anyway, but if there are some add-ons that are useful for you, you could do something like start with them all disabled and enable them one by one until you find the particular one that is messing things up and then get rid of just that one.

- Michael

Looks like the culprit was "Yontoo."
Also uninstalled "Spigot pdfforge toolbar" and "Zugo search toolbar."