Normals on a surface are shifted into space, not on right location?

Hey everybody,

I managed to make a ruled surface (hypar), make some subdivisions by a grid of lines and now I want to have on each intersection point of the gridlines a vector which is normal to the surface. When I use 'evaluate surface' and feed the surface and then the intersection points into uv, I get a very strange solution for the normals:
- when I do not reparametrize, I get strange vector which are shifted into the X and Y direction. not ok
- when I do reparametrize, I get normals scattered into space, seems they are a factor 10 to big, it's all wrong.

What am I doing wrong?
See PDF with pictures of the two wrong solutions and the definition file

Attachments:

Ruled HYPAR.ghx, 213 KB
reparametrize.pdf, 509 KB

Replies to This Discussion

Permalink Reply by Benjamin Golder on October 26, 2009 at 2:36pm

it looks like you are feeding points into the evaluate surface component where you should be using uv coordinates instead. try putting a "find closest point on surface(or brep)" in between your intersection points and your evaluate surface component. take the uv data out of the closest point on surface component and feed that to your uv input for evaluate surface.

uv coordinates are in a different coordinate system that is based on the surface, they do not correspond to xy coordinates of the same value.

Permalink Reply by Niels De Temmerman on October 26, 2009 at 4:37pm

Hey Benjamin,

genius! thanks alot. it works a treat. Will remember that function 'closest point on surface'

cheers,

Niels

Permalink Reply by Paolo Cappelletto on October 27, 2009 at 5:03am

Hi guys
can you check this, I'm not sure to understand.
I'm a bit confused about the normals...
Thanks
Paolo

Attachments:

RuledHYPAR_00.ghx, 246 KB

Permalink Reply by Niels De Temmerman on October 27, 2009 at 5:52pm

hey paolo,

I've uploaded the file which does exactly what I wanted, thanks to the function 'find closest point on surface', which was tipped to me by Benjamin.

Just check it out

Attachments: