Mapping a rectangular grid onto a surface

Hi guys,

I have been trying to map a rectangular grid onto a triangular surface but i get a flipped surface (please see image).

Would you have any idea why this is happening?

many thanks,

Arthur

Attachments:

MappingRecgrid.ghx, 187 KB

Replies to This Discussion

Permalink Reply by Giulio Piacentino on May 17, 2010 at 1:48pm

Hi Arthur,
please see if the Three Musketeers method helps (attached).

- Giulio
_______________
giulio@mcneel.com
McNeel Europe, Barcelona

Attachments:

MappingRecgrid_all_for_one.ghx, 170 KB

Permalink Reply by Arthur Mamou-Mani on May 18, 2010 at 2:11pm

Thank you very much Giulio,
i have tried the definition but i still cannot input several triangles with it it seems.
Would you know how i could do that:
http://www.grasshopper3d.com/forum/topics/multiple-geometries-to-ma...
?

Permalink Reply by Giulio Piacentino on May 19, 2010 at 8:11am

Hi Arthur,

please have a look at this definition. It's comparable to the previous one, except it makes use of trees to keep the lists in the right order for many surfaces. The brep faces must be untrimmed.
Hope it helps,

- Giulio
______________
giulio@mcneel.com
McNeel Europe, Barcelona

Attachments:

MappingRecgrid_all_for_one_many.ghx, 193 KB

Permalink Reply by Arthur Mamou-Mani on May 19, 2010 at 8:24am

Thanks a lot Giulio! it's brilliant once again :)
I'm still a bit confused as to when to use a path mapper...

Permalink Reply by Tushar Sharma on May 22, 2010 at 6:10pm

hey guys,
i tried applying this definition.. i am not able to make an untrimmed surface.. as i had polylines and applied planar surface, after reparameterizing it, it gives me trimmed surface..what shall i do in this case?

thanks

Permalink Reply by Giulio Piacentino on May 23, 2010 at 4:48am

Hi Tushar,

examples of untrimmed surface components are: "4Point Surface", surface from points.

Most lofts, sweeps (1 and 2), pipes, sum surfaces, extrusions, revolutions are also giving untrimmed surfaces, but when the input curves have discontinuities they might give polysurfaces (breps containing many surfaces).

Patches and planar surfaces and Boolean solid operations are returning trimmed surfaces. Surfaces having more than 4 discontinuous vertices need in general to be trimmed.
I hope this is helpful.

- Giulio
_______________
giulio@mcneel.com

Permalink Reply by Tushar Sharma on May 23, 2010 at 4:59am

hey giulio,
i have made surfaces using surface 4 points in my problem.. i reparameterized it as well..still it gives trimmed surface.. how can i go ahead with it?

Thanks

Permalink Reply by Tushar Sharma on May 23, 2010 at 5:20am

hey,
when i tried surface from points, i have 3 points, i dont know what values i should be putting in 'u' and 'i' of the component
thanks

Permalink Reply by Giulio Piacentino on May 23, 2010 at 12:15pm

Hi again Tushar,

yes, if "4Pts surface" only receives 3 points it constructs a trimmed surface. You can use surface from point grid with 4 points, where two of them are coincident, to obtain an untrimmed triangular NURBS surface. However, please notice that the parametrization will be small in the area of the two coincident vertices.

I'm attaching a very simple example (Gh 0.6.0059)

I hope this is helpful,
- Giulio
________________
giulio@mcneel.com
McNeel Europe, Barcelona

Attachments:

threePointsSrf.ghx, 22 KB

Permalink Reply by Giulio Piacentino on May 24, 2010 at 5:10am

Hi Tushar, could you please draw a small sketch of what mapping you would want to achieve? I think I do not understand.

- Giulio
_________________
giulio@mcneel.com
Barcelona

Permalink Reply by Luis Fraguada on May 23, 2010 at 2:11pm