Why cannot you make a straight section with splines That has more than 2points?

[cekuhnen]

[PhilProcarioJr]

@cekuhnen

I was just wondering this the other day...thanks for posting this.

[jeff_strater]

I'll take a shot at answering, but with some trepidation.  Be kind...  I am not a mathematician.

The reason is that Fusion splines are "energy minimization" curves.  That is, the spline solver tries to minimize an energy function across the entire curve.  So, changes to any of the fit points or tangent handles actually affects the entire curve.  You can see this in this screencast:

This "global effect" is what is preventing your "I want" case.

We inherited this spline solver from Inventor.  The behavior there is the same.

As has been said before, the team is working on CV splines, which will not have this behavior.

Jeff

[cekuhnen]

@jeff_strater

So that the changes to the spline translate to changes across the complete spline makes sense.

I am still struggling where the G2 handle could be useful for "on" a spline.

The tangent one can produce a nice and smooth arc around a center fit point where with the G2 handle

I can change it to a way that the curvature is crazy.

I know that with making the G2 handle very tine I even bend the spline inwards

Most times I use the G2 constraint when making a blend curve which seems to be the most common application

while there the G2 handle is disabled for the blend curve - only the G1 handle can be activated.

Also the handle bug is still present:

[jeff_strater]

Agreed.  The curvature handles are of questionable value.  I suppose you could argue that it's just another way to modify the shape of splines, but that is more control than I ever need, so I tend to stay away from them.

And you are correct about the bug.  I have seen that myself.  Thanks for the reminder.

Jeff

[cekuhnen]

@jeff_strater

Don't misunderstand me actually. In certain situations spline is a much nicer tool than CV.

I see the spline a piece of plastic that wants to destress and I think your way of explaining it follows a similar logic.

For smooth shapes like this (espresso damper) it is ideal and much nicer than in Alias - also the workflow in Fusion is better.

In Alias I could also work with a degree 3 but it seems I have less the smoothness of the spline specifically the tip in Fusion is pleasing.

[cekuhnen]

@jeff_strater

I just finish another old model just now new in Fusion and it is a very organic shape.

For sure getting this smooth and even with a nice curvature comb is D like DRAMATICALLY easier than in Alias with multiple curves

For this type of a model the splines are actually ideal !!! You always end up with good graphs a lot faster than all that CV pushing with a CV curve for something like this.

[cekuhnen]

@jeff_strater

Here is a finished version but unfortunately the Patch tool does not really deliver accurate G1 or G2 surfaces as one can see the break in the zebra and shaded highlight.