subsurface extraction

hi, first of all, pardon for my bad english.Im a grasshopper newbie and hope u guys can help me out with my problem.

I have an issue with extracting a subsurface from an untrimmed surface basically I wanted to create a definition by inputting a surface and then GH will simply create a window frame based on that input surface.

[I have attached my definition and a screenshot for you guys to have a look.]

I added a slider to control the dimension for the frame. I dont wanna use the "offset crv on Srf" approach, because that component seems to be sending the definition to rhino and then convert it back to GH.

so I decided to use subsurface extraction to get the untrimmed surface which then I can feed it to another definition.

the problem is that because the Srf needs to be reparameterized, I cant control the frame dimension. I added simple math definition ( Frame width/Crv Length in U direction ) to translate the frame dimension to fit within number 0.0 to 1.0

the problem is that if the surface is trapezium, the frame width will slightly change on one side of the surface. ( because of how UV works )

is there any way to solve this problem?? any help would be appreciated.

thank you guys....

Attachments:

help guys.PNG, 153 KB
help me guys.gh, 5 KB

Replies to This Discussion

Permalink Reply by Runnie on January 14, 2015 at 7:50pm

wow guys awesome definition!!! thank you mate..really appreaciate ur help guys. I am studying all your def.now. sorry for the late reply, I v been on business trip for few days

so there is basically no way of getting a fully Untrimmed surface output without having to rebuild the Srf from network SRf. these trimmed and untrimmed paramter has been an issue in NURBS modelling IMO, but I heard the development team from TSPLINE will come up with the brand new algoritm to deal with Trimmed SRF in their next TS release, so I wonder if rhino mcneel will do the same to hv a better control over trimmed SRf.

one more silly question maybe u guys have heard about=

knowing that GH is widely used by architects and designers I wonder if there is any implementation from GH to WACOM tablet? WACOM stylus can give a complex input to GH because it sends thousands of thousands of data in seconds depending on your pen pressure and tilt angle (it is couple of times has more resolution than standard computer mouse as well)

a kind of complex input can be used to sculpt surface with much freedom (Similar like Zbrush)

as a designer myself, I am looking forward for rhino+GH to be a little more considerate towards artist and designer, it is a scripting plug in, yes, but maybe you guys have your own opinion about making GH much more versatile and really kicking ass? :PP

thank you, as I would say in Chinese = XIE XIE ^_^

Permalink Reply by Riccardo Majewski on January 15, 2015 at 6:40am

Subsurface extraction using original surface isocurves would be perfect ONLY if the original surface is a flat parallelogram, where isocurves are ALREADY offsets of external edges.

So you can perfectly "shrink" the extracted trimmed surface.

In other cases, you have to rebuild.

Instead using surface network, you could use Surface From Points (SrfGrid) component, but it is similar.

For the wacom question...

I have no knowledge about external implementations for grasshopper.

Normally it's better to open a new discussion for questions out of original thread, there you should receive more answers, maybe...