Hi Felix, re: flow question

> I assume something can be done to put the ring on the
> outside of the rounded surface.

For now you can either sink the ring down to the bottom of the plane surface, or you can select the rounded surface and run the Flip command on it to flip its positive surface normal direction to the opposite side:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#flip

Right now surface-to-surface flow will use the positive surface normal direction of the surface for the mapping, and with open surfaces this can often be pointing in a way that you didn't really expect - it's dependent on things like what direction (clockwise or counterclockwise) you drew some of your initial curves in or things like that. If you make things into a solid then it will orient surfaces to have the positive normal direction pointing to the outside of the solid.


> Also, as you can see both surface have the same Y length,
> so I expected the ring to have the same Y value as the original
> and since in the X direction the surface have different length
> I expected the ring to be strech.

So what is happening here is the U and V directions of the rounded surface are swapped from what you're expecting.

Every surface has a kind of UV space associated with it, similar to how texture mapping works in rendering. One direction of a surface's control point grid is the U direction and the other direction is the V direction. They're not really forced to be aligned in any special way to the world axis directions.

Flow actually maps things from one UV space to another UV space, it doesn't really map things in world x/y/z axis directions - the directions all come from this UV space.

So in this case the U direction of the plane is the horizontal one, but the u direction of the surface is the vertical one it ends up mapping from one direction to the other causing this distortion.

Right now I don't have any way set up to swap the UV axis directions so the solution right now would be to squish the plane so that it was horizontally the size that you wanted to map to the vertical direction of the rounded one.


> I think for cases like the first example, it would be nice to
> have somekind of option to flip the ring to the inside/outside <...>

Yeah I want to make some way to control it - that's an area that I still need to work on adding to the Flow command, I just didn't want to delay the beta any longer before finishing that up.

I'll probably be trying to make it work by paying attention to which corner you click nearby on each surface when you select them and then matching those corners together, that should make it so that you won't have to worry about u and v directions anymore.

For curve to curve flow that works already - it matches things starting with the ends that you clicked closest to but I didn't finish the equivalent thing for surface to surface flow yet.

- Michael