Normal Direction..again, sorry!

Hi all!

Having some problems pointing my surfaces normal in one uniform direction. I'm trying to generate an inner surface for this folded geometry (similar to a 'shell' operation) to eventually be left with separate panels. I'm starting with the intersection points at each of the surfaces corners. I'm thinking if i can find the 'average' vector direction at each intersection point I can use this to generate the intersection points for the inner surface (or outer)...

The problem is once I start to evaluate the surfaces that share each intersection point, their normal's appear to be pointing in different directions.. I have been through many discussions on the forum which have raised similar issues (including flipping curves and surfaces using guides) but having no luck resolving the problem. I have attached a definition showing my approach... Is there another way? can anyone help?

Thanks

Dean

Attachments:

vector direction.ghx, 386 KB

Replies to This Discussion

Permalink Reply by Shawn Fernandez on November 17, 2010 at 1:33pm

I was thinking that you generate a vector from the reference point to say the start point of the normal vector and then test the angle between the two vectors and make sure they are less than pi/4. The method you described will create positive vectors because they really aren't considering the direction of the surface, but simply using the points as basic inputs for making a generic vector.

I did something similar here for a set of curves to make sure they were oriented in a clockwise manner.

Attachments:

Clockwise Curves.ghx, 133 KB

Permalink Reply by Shawn Fernandez on November 17, 2010 at 2:05pm

Sorry should be less than pi/2 in your case if you use the reference point as the start.

Permalink Reply by Dean Foskett on November 17, 2010 at 2:15pm

If i remove the reverse x axis and make it less than pi/2 I get two faces still flipped... getting close!

Could it be how the surfaces are generated after using planar component?

Permalink Reply by Dean Foskett on November 17, 2010 at 2:20pm

image attached

Attachments:

angle curve.jpg, 109 KB

Permalink Reply by Shawn Fernandez on November 17, 2010 at 2:47pm

I think you mostly got lucky! XD I didn't mean for you to incorporate the file I gave you exactly, but rather to use as an example. I meant for you to compare the angle of the two vectors in a similar fashion as I did, not apply the sample to your curves. Try the file I posted below, it may need some tinkering still.

Attachments:

temp.ghx, 228 KB

Permalink Reply by Dean Foskett on November 18, 2010 at 12:23pm

A seriously big thank you to both Vicente and Shawn for their help – turns out the 2 definitions are very effective at solving the problem in very different ways.

Vicente, the script component has saved valuable time by computing the normals.

Shawn, I used the pattern from the flip component to reverse some of the lines between the two vectors I generated, it worked a treat!

Permalink Reply by Dean Foskett on November 18, 2010 at 12:26pm

Definition images attached

Attachments:

Mesh Def.jpg, 89 KB
Pi2Def.jpg, 142 KB

Permalink Reply by Shawn Fernandez on November 18, 2010 at 1:44pm

Sweet! Glad I could help. There's usually more than one way to get to where you need to go. =)

Permalink Reply by Guilherme Bera on July 10, 2017 at 3:59pm

Hi, I really don't want to bother anyone in old threads, but it seems to be exactly what I'm looking for.

The problem is that I just started in GH and I can't recognize all this icons from definition. Would you mind to post the image with the full names, please? Thank you!