Carve by arclength instead of parametric 0..1 ?

Forums Technical Discussion Carve by arclength instead of parametric 0..1 ?

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geometryNerd: Member; 11 posts; Joined: Aug. 2017; Offline

Dec. 19, 2017 8:50 p.m.

Is there a way to use Carve SOP and provide the first U/Second U in meters rather than a U parameter (0..1) ?

I have real world measurements curves (adaptively sampled, so more points where more curvature) and I need to “shave off” a specific length.


dedeks2999: Member; 85 posts; Joined: May 2011; Offline

Jan. 13, 2018 7:37 p.m.

http://www.sidefx.com/docs/houdini/expressions/arclen.html [www.sidefx.com]

— dedeks 3000 —


matthias_k: Member; 483 posts; Joined: Dec. 2006; Offline

Jan. 13, 2018 11:36 p.m.

@geometryNerd
If I'm right: no

But you can get the length as dedeks3000 pointed out and then
edit parameter interface…
add some math, to get your “meter” slider

Attachments:
arclen.hip (64.0 KB)

English is not my native language, sorry in advance for any misunderstanding :-)


vusta: Member; 555 posts; Joined: Feb. 2017; Offline

Jan. 14, 2018 8:52 p.m.

easy…

(you could just skip the CTRLS and just use the value ladder in the carve…but it's more userfriendly)

(don't know the exact meaning of ‘shave off’…ie. from which end…but I'm sure you can adapt/flip the logic to suit your needs)

Edited by vusta - Jan. 14, 2018 21:06:17

Attachments:
vu_CarveByDistance.hipnc (62.5 KB)


Aizatulin: Member; 471 posts; Joined: July 2005; Offline

Jan. 15, 2018 3:38 p.m.

Hi,

just in addition, you can also create a carve tool with the attribute wrangle. After you've calculated the length for a curve (arclen not working in wrangle for me ?!), you can use the length to build your own curve by defining a curve function by another wrangle. Resampling is useful before (it is doing the main work), to get an uniform sampled curve.

Attachments:
CLen.hipnc (82.2 KB)


dedeks2999: Member; 85 posts; Joined: May 2011; Offline

Jan. 15, 2018 4:42 p.m.

hye Aizatulin,

Did you try this function in your code ?

http://www.sidefx.com/docs/houdini/vex/functions/primarclen.html [www.sidefx.com]

Apparently, you can also get it from the arclength primitive intrinsic attribute

— dedeks 3000 —


Aizatulin: Member; 471 posts; Joined: July 2005; Offline

Jan. 16, 2018 1:35 p.m.

Hi dedeks,

Thanks for the advice. primarclen works fine for me, except one little thing, that there seems to be no overloaded version, where you can use the input id instead of the whole path string. Btw is there any function which maps the input id to the fullpath of the input?


dedeks2999: Member; 85 posts; Joined: May 2011; Offline

Jan. 16, 2018 1:55 p.m.

hye Aizatulin,

Look here :

https://www.sidefx.com/forum/topic/49076/ [www.sidefx.com]

— dedeks 3000 —


Aizatulin: Member; 471 posts; Joined: July 2005; Offline

Jan. 16, 2018 2:03 p.m.

Hi,

Thanks, I've forgotten that the Input count starts with 1 and not with 0 for @OpInput*.


Octop: Member; 13 posts; Joined: Oct. 2013; Offline

March 4, 2018 9:48 a.m.

I RFEed this once. I got this reply.

“I am told the Carve Curve Arc is available as a prototype node (ie, not formally supported but available for use at client's discression).
To install it, run ‘proto_install’ in a command line and follow the commands.”

So it's built in…in a way.

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