Hi Michael,

Only just got the chance to have a play with the new Beta & specifically I wanted to try out Flow.

Having read the posts within this thread, I figured I had a reasonably good idea on how it should/would work...
...so was kind of surprised to see the items mirrored or facing the opposite way around?
Not a big issue as I can easily rotate the ring 180 degrees, but more curious to know why this has happened & how to not do it again??
I'm assuming it'll be something to do with the various surface constructions & their directions???

regards Colin

Hi Colin, that happens when the u and v directions of one of those surfaces are swapped from what you want.

Right now the Flow command just maps from one UV space of a surface to the natural UV space of the other surface and doesn't yet have any options for controlling how they should be matched.

At the moment the easiest way to deal with that is to re-arrange your plane - squish your plane so that it is long in the other direction and then rotate the plane 90 degrees (and possibly flip it) and that should get you what you need.

That won't be necessary in the next beta though - in the next beta I've added a way to control how the UVs will match by paying attention to where you click on both the base and the target surfaces - you'll click next to an edge near one side of the edge, and then click on the matching spot on the target surface and it will then swap and reverse UVs as needed to make those spots be aligned.

So this problem should get better in the next beta - you'll just have to pay attention to where you are clicking on each surface.

- Michael

Hi Colin so actually in your case there it's not that the uvs need to be swapped, it's that you need the v direction to be flipped. At the moment you would do that by rotating the plane by 180 degrees around its middle along its long direction.

- Michael

Hi Colin, so here's an example for how it will work in the next beta.

You'll click near one corner of the base surface, near one side of it like this for example:



Then on the other surface you click on the equivalent spot where you want that to match up with, so you would click near this spot:



Then that will produce this kind of result:



So you won't click exactly on a corner - you click closer towards the edge nearby the corner to one side of the corner or the other side so there are 8 possible zones.

Anyway then it will swap or flip any UV directions as needed to make the output match those spots up.

- Michael

Hi Colin - one other note - with something like this where you want to have the deformed result loop around and have ends touching each other you will probably want to leave end caps off and then use Join on the result to glue those edges into a solid.

If you leave end caps on you'll have some coincident caps in the final result.

Also to make a good join make sure pieces that will touch go exactly to the edge of the base plane - one of the tubes in your example file here goes over the edge by a just a tiny bit (like 0.008 mm) but that's just enough distance so that it won't join to its partner when it is deformed. With that piece trimmed off then it will join.

- Michael

Hi Michael,

Thanks for all of that info & the work around.

When creating the Base Surface, I'm just wondering if currently there's a "preferred way" of making it?
So for example is it preferable to use a Base Surface made from Sweep more than a Loft or Extrude surface??
I already know that each of those commands produces a slightly different surface when you've turned the Points On....
...so just wondering if this has any bearing on those UV directions too??

OK, so that selection arrangement for use within the next Beta is similar to how the process currently works within Rhino4 now.

Thanks for the heads up on the End Caps too.
I'll be sure to remove any of the Caps on those items prior to doing the Flow.

regards Colin

Hi Colin,

> So for example is it preferable to use a Base Surface made
> from Sweep more than a Loft or Extrude surface??

Are you talking about the base surface here, or the target surface?

For the base surface pretty much the easiest thing is one of the plane drawing tools under Draw solid > Plane.

For the target surface it really depends on what kind of shape you want, since those various tools make different kinds of shapes so it's not like you can always swap one for the other. But yes, as far as UV layout goes it is possible for different construction methods to put the UVs in different directions, I'm not sure of the details about that for each one right now. In the next beta it won't really make a difference though anyway.

Some commands may benefit from doing a Rebuild on some of the curves before constructing with them when you know you want to use them for Flow - that's because the result of Rebuild is evenly parameterized. So if you see something like a flow on to a 1 rail sweep is kind of stretching or compressing somewhat in various zones, try doing a Rebuild on the rail before doing the sweep - that can result in a sweep that works better for a flow target.

- Michael

Hi Michael,

>Are you talking about the base surface here, or the target surface?<

Thanks again for all of that info, & yes, I was only referring to the Base Surface.

regards Colin

Thanks for Flow and the ShrinkTrimmedSrf explanation, it was frustrating how my little globe test failed at first.
Now it works!

(Old map without South Sudan by the way...)

Bart-Jan

It's funny how, even though Flow has only been out for a few feeks, I've already naturally used it about 5 times where it would have been really difficult without it.

Such a handy feature :)