Geometry nodes – sweeping a cross section along a path, and modulating its thickness

[erikitect]

I see you can create a shape by moving a cross-section curve along a directrix curve, and thereby generating a mesh.  (for instance a circle along a line yields a cylinder) 

But I am wondering, can you vary the size of the cross-section as you go along, and thereby have it more bulbous at one end, for instance?

[Martin Bergwerf]

Hi @erikitect ,

Of course you can!

For instance:

[erikitect]

Thank you. I was thinking that the radius factor would have to be plugged into the socket of the profile curve rather than the first curve. And so I was wondering whether you would have to copy an attribute from one curve to another in a complicated way.

But if it’s as simple as you say, then I can probably do what I was thinking of relatively easily.

[erikitect]

Thank you for your suggested node diagram.

I am coming back after actually trying it.

I want to modulate the curve along its length, so it is bulbous at one end and then tapers off. 

My attempts to do that by putting a “Float Curve” node or a “Color Ramp” node in the place of the “Multiply-Add” node in the diagram do not work.

My idea of just what I am controlling seems to be wrong. If I change the curve a little differently, the whole curve disappears.

[Martin Bergwerf]

@erikitect ,

If you use the Factor output of the Spline Parameter Node, you always get a result from 0 (beginning of Curve) to 1 (end of Curve).

That might be easier to manipulate with Math or other Nodes.

The Length goes from 0 to the length of the Curve (duh).

[Author]

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