Trying flow for the first time. No matter where I click on the source and destination surfaces the text is a mirror image or sideways. I tried reversing the normal and it didn't help. What I am missing?

Thanks, Andy

Hi Andy, there is a description on where to click in the help file here:
https://moi3d.com/4.0/docs/moi_command_reference8.htm#flow

For your case here you would want to click not directly in a corner, you need to click slightly away from the corner and then do the same on a matching location on the target surface.

So with a base surface click here:


You would then click on the target surface here:


- Michael

Here is a demo video using your file. First I hide the curves you've got there so that they don't interfere with selecting:



- Michael

Thanks - but this is weird. When I clicked in that area before it mirrored the text. OK so reopening my file I now try clicking in all the places I did before and it works as expected every time. In fact I can't get it to mirror the text or put it sideways, when before that is all it did. OK now by trying really hard I found one spot that does it.

Any ideas what is happening?

Andy

HI Andy, well if you click right on a corner or on a spot equidistant from the edges you'll get unpredictable results. You need to click a little ways off of the corner, along one of the edges.

What happens is that it uses the edge closest to where you clicked and if you don't specifically target one edge you could end up accidentally targeting an unsuitable one.

- Michael

Here is another one. I click on the points indicated I expected the 'C' to be near the second click. How can I control where the 'C' ends up?

Thanks, Andy

Hi Andy, if you've got a circle there you can just rotate the result around the circle's center point or rotate the circle before doing the Flow.

Another option would be to trim open a small empty spot on the circle so it's an open curve, then you can match it by which end you click closest to when selecting the base and target curves.

You can also use this plug-in to relocate the "seam" for the start point of a closed curve:
http://moi3d.com/forum/index.php?webtag=MOI&msg=10125.8

- Michael

Thanks however the behavior in this case doesn't match 2D surfaces where the clicked points are aligned. I think MoI should be able to automatically match up the two clicked points so the behavior is consistent.

Andy

Hi Andy,

re:
> I think MoI should be able to automatically match up the two clicked points so the behavior is consistent.

It would not be consistent though - on open curves it does not just use some point internal to the curve, it controls which end of the curve is used.

The way you are asking for would use some point internal to the curve that was not controlled by snapping.

- Michael

Well I don't really understand that explanation. It sounds like you are talking about stuff that is internal to how the geometry is defined. But for me as a user I am clicking on the end of a line and clicking on the point of a circle so I would expect intuitively that the software matches those two points up.

Andy

I tried a lot of different locations, including the one you demonstrated and now works for me also after closing and reopening the file. Andy

Hi Andy,

re:
> But for me as a user I am clicking on the end of a line and clicking on the point of a circle so I would
> expect intuitively that the software matches those two points up.

Let me try another way to describe it - when you pick the target curve in the Flow command, you are in the "select an object" type of action (object picker is active). That's different than the "pick a point" type action where things like snaps are available (where a point picker is active).

The pick point in the "select an object" type action is only used in MoI to determine things like which end of an open curve was closest to your mouse. It isn't used anywhere to generate a point somewhere on the interior of a closed curve which is what you are describing.

The problem with trying to use it for that is that you would not have good control over the point location because you don't have object snaps going then. So the point that you would get would be some fairly arbitrary location. If you wanted to control it to be at an intersection with another curve or something like that you would not be able to get that.

- Michael

OK, so why is point selection not used here? Andy

Hi Andy,

re:
> OK, so why is point selection not used here? Andy

Because the main thing it's looking for is an object and the object picker is best at selecting objects.

Probably what it should do is show a point on closed curves that you could drag in the options stage of the command to change the start location. For now though with a circle the start location can be easily changed by rotating either the circle or the result of the flow around the circle's center point.

- Michael

When I flow the filleted box onto a surface it distorts the ends. I double-checked and the base surface is the same length as the target surface (generated from unwrapcurve). Any ideas why it is doing this?

Thanks, Andy

Hi Andy, it's because the target surface has uneven parameterization, some areas are stretched out and some are compressed in how the surface's UV parameter space relates to 3D space. If you turn on surface control points you can see some neighboring control points are close together and some are far apart from each other.

A couple of solutions are to use the Rebuild command (https://moi3d.com/4.0/docs/moi_command_reference10.htm#rebuild) on your original curve used to generate the surface and extrude a new one out from that. That will have arc length parameterization and so won't have areas of compression and expansion like your current surface has.

Another solution is to use curve-to-curve flow instead of surface-to-surface flow. Curve-to-curve flow matches based on distance traveled along a curve rather than matching by UV parameter space like surface-to-surface flow.

Also note that your object is kind of mangled as a result of applying a fillet with a radius larger than will fit in available space.

- Michael

Your volume is not a solid (not a problem) but not well "proper" finished!

Better to put the plane at the middle of the object
You can of course put any length of flat thickness between the 2 curvated forms! :)

Ok, thanks to both of you. I didn't realize the base plane can be in the middle of an object. Andy