Is there any tip concerning "Blend Curve" ?

I want to create Blend Surface component.

So I choose that 4 curves and blend curve for first step.

But as you can see, that "Blend Curve" method has "Direction(?)" or something.

Curve.DoDirectionsMatch(c1, c3);
Curve.DoDirectionsMatch(c2, c4);

Curve ref1 = Curve.CreateBlendCurve(c1, 0.5, true, BlendContinuity.Tangency, c3, 0.5, false, BlendContinuity.Tangency);
Curve ref2 = Curve.CreateBlendCurve(c2, 0.5, false, BlendContinuity.Tangency, c4, 0.5, true, BlendContinuity.Tangency);

That script is correct 50%. (Last picture)

You guys have any tip ?

Replies to This Discussion

Permalink Reply by David Rutten on February 11, 2014 at 8:09am

What if you compare distances between end-points to figure out whether or not to flip the curves?

curve A

A0---------------------------A1

curve B

B1--------------------------B0

You define distances:

|A0 B0|
|A0 B1|
|A1 B0|
|A1 B1|

And find the smallest one. Then, based on the number of the shortest distance:

Flip A, Leave B
Flip A, Flip B
Leave A, Leave B
Leave A, Flip B

A more advanced metric would be to create all 4 blends, then pick the one that is shortest. Maybe that works better for what you want, maybe not.

David Rutten

david@mcneel.com

Permalink Reply by Digit on February 11, 2014 at 8:36am

Hi David ~

That's so nice !

Ah ! One more question.

"Line" has the "Flip" method and "Curve" has the "Reverse" method.

All those methods have same effect ? (Flip direction)

Permalink Reply by David Rutten on February 11, 2014 at 10:36am

They are not entirely the same. When you flip a line, the line domain is still [0,1] as lines always use a [0,1] domain. However when you reverse a curve, the domain changes from [a,b] to [-b,-a]

David Rutten

david@mcneel.com

Permalink Reply by Digit on February 12, 2014 at 12:49pm

How can I do "Flip Curve" ?

Flip is only for the "Line" ..

Permalink Reply by David Rutten on February 12, 2014 at 2:17pm

You use Reverse on Curve. You just have to realize that the curve domain will be different before and after. If you want to keep the same domain, then you need to use:

Dim domain As Interval = crv.Domain

crv.Reverse()

crv.Domain = domain

David Rutten

david@mcneel.com

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