Hi Michael,

In the Sweep menu there are the options:
Pointy end,start,both pointy

I is giving me example 'A' which is useless to me,
i expected example 'B'

So the unless someone on this forum needs it that
way,you could eliminate it in the next moi3d version
(no offence)

Paolo

I think this is how it was intended to be used. (see jpg)
(I like it's working very much and I think most of us would.)

Brian

Hi Brian,

I tried to follow your example:

Example 'A' is ok but 'B' and 'C'
appear strange to me

Hi Paolo, the part that you don't like there is the blending that happens as one profile is being morphed into the shape of the next or previous profile in the sweep.

This morphing is done using a kind of "ease-in / ease-out" method which results in the shapes that you see there.

That style of blending allows for the surface to be smooth at that center point.

If there was no kind of ease-in / ease-out at all and just a direct averaging kind of blend, it would result in a shape like this:




That does not work very well because the surface has an abrupt shift in shape where it hits a profile curve.


The current blending works with this kind of a function to make a smooth step from one profile to another (in the case of a pointy end then one of your profiles being blended is a point):



It sounds like you want a blending profile more like this instead:




Unfortunately it is not an easy thing for me to just switch everything over to use a blending mechanism like that instead - one mechanism is not automatically "better" than another and actually in other cases the current blending function is probably the more expected result, for example here:




If the blending worked the way you are talking about, the tube would have kind of "fat ends" where the center profile would have a sort of more exaggerated weight than the ending profiles.

The current mechanism treats each profile with equal weight which I think is probably the best for a default processing.

So it is not really an easy thing for me to change without causing undesirable side effects.

For now at least if you want to have more exact control over the way the sweep is shaped, a 2 rail sweep will be a better choice for that like you showed previously since that gives you a different method to control how the profiles are shaped since they will continuously stretch to match those guide rails in that case.

With one-rail sweep (without a scaling rail) the only method applied to the profiles is the ease-in / ease-out blending and nothing else affects them.

- Michael

Hi Paolo,

> Example 'A' is ok but 'B' and 'C'
> appear strange to me

Actually though all of your examples are doing the same thing.

If you sweep along a line with "both pointy" enabled, you can see what is happening more clearly:



All the examples that you show are variations on this shape.

One other factor though is that blending can currently be stretched out to different proportions depending on the control point spacing of the path curve, so this may be causing some additional stuff there that you don't like.

I do plan on correcting this for v2 so that the shaping will be based only on the distance traveled along the rail curve instead of being sensitive to the spacing of the curve's control points. But it is not an easy thing to fix, I am currently planning to do this as part of a batch of work to sweep that I would like to do a bit later on in the v2 development.

- Michael

Thanks Michael,

>> depending on the control point spacing

I experimented by adding controlpoints on the
rail curve,and then snapping those points on
the endpoint of the rail, giving me a promising
result