change direction of a surface

I have a bunch of planar surfaces, but the direction of the surface ( normals ) are not consistently pointing either outward or inward, it is a combination.

Is there an easy way in GH to change the normal direction of the surfaces, in such a way that they all point either outward or inward ( meaning, some will change some will stay the same ) ?

thanks

Replies to This Discussion

Permalink Reply by Chris Tietjen on June 13, 2013 at 2:50pm

Surface>Utilities>Flip

Permalink Reply by marcello on June 13, 2013 at 7:48pm

that seems to flip all of them, what I am looking for is to find a way to flip some of them so that all of them face the same way, does that make sense ? I have difficulties conceptualizing what to assign or how to go about to select the ones that are different. is it a list thing or can I select the orientation direction towards a centerpoint or something like that

Permalink Reply by David Stasiuk on June 14, 2013 at 12:55am

If you have one surface you can always identify as being oriented correctly, you can feed it into the "g" input on the flip, and it will only flip those that aren't oriented in a similar direction. Otherwise, if you have a guide vector that's pointed generally in the correct direction that you can use to compare your other surfaces to, then you should extract all of their normals, do a vector angle test between them and your guide vector, and pass this value to a conditional expression to generate an index for a "pick 'n' choose" component: If(x>Pi/2,0,1). Run your surfaces through the flip component, and then feed your flipped surfaces into the 0 input of pick 'n' choose and your original list into the 1 input.

Permalink Reply by Pablo Mora Chatski on January 15, 2018 at 7:02pm