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hypersuperduper
01-31-2018, 04:15 AM
is it possible to have two instances of one object, but set a modifier or surface or something on one of the instances to flip the normals so that back faces become front faces?

probiner
01-31-2018, 05:58 AM
Input module has Polygon side, which is either 0 or 1 depending on the side of a double sided mesh. Use that on a Mixer or Material Switch.

Cheers

gar26lw
01-31-2018, 06:14 AM
of course that assumes a different material. this is where some global override would be useful.

now i don’t know if you can do this in the new 2018 but in 2015 i know that you could use instance id or object id to dictate a switch between materials.

i used shadermiester and dpont nodes a lot so i cannot remember if this is achievable with std. nodes.

MonroePoteet
01-31-2018, 07:33 AM
As probiner says, you can use the Switch node in the Surface node editor to select a different Material for each side of the polygon(s). It doesn't actually flip the normal of the polygon, though, if you're requiring the actual normal be flipped for a math calculation or some such.

139859

mTp

hypersuperduper
01-31-2018, 07:58 AM
Thanks for the help everyone. I was hoping to flip the normal of the polygon though. I wanted to see if it was possible to do an inverted hull outline effect in layout without having to do it manually in modeler. or resorting to another application like blender.

Sensei
01-31-2018, 10:22 AM
Normals will be flipped if you will use (item) Stretch -1,-1,-1

hypersuperduper
01-31-2018, 12:14 PM
Normals will be flipped if you will use (item) Stretch -1,-1,-1

this also mirrors the item however. even by then using a Mesh info node to move the points back to the correct positions I wind up with inverted normals, but the faces are not flipped.

Sensei
01-31-2018, 12:19 PM
Geometric (polygon) normal is calculated from point positions. 1st, 2nd and the last vertex from polygon are used (cross product between 1-2 and 1-last).

Pressing 'f' in Modeler is simply changing order of points in polygon.
From 1,2,3 to 3,2,1 (or 1,3,2) (for example triangle).

Some times it does matter what is order of points, whether it's 1,2,3 or 2,3,1 or it's 3,1,2.
That's why I made Reorder Points tool.

https://www.youtube.com/watch?v=iSqYGkQAJFc


https://www.youtube.com/watch?v=iSqYGkQAJFc