[Closed] A query about trimesh selections

i don’t think so…
is not always going reverse to the pair edge.

Lets say we have triangles [1,2,3] and [4,2,3] . Edge 2 (2,3) of triangle 1 and edge 2 (2,3) of triangle 2 are ‘reversed’ but both are going same direction. But we can change the triangle 2 to different order – [4,3,2] for example. In this case second edges of triangles are going reversed to each other.

That would also flip the face normal.

(
	obj = converttomesh (plane length:100 width:100 lengthsegs:1 widthsegs:1)
	
	f1 = getface obj 1
	f2 = getface obj 2
	format "  face1:%   face2:%\n" f1 f2
	
	n1 = getfacenormal obj 1
	n2 = getfacenormal obj 2
	format "normal1:% normal2:%\n\n" n1 n2
	
	setface obj 2 [f2[1],f2[3],f2[2]]
	update obj
	
	f1 = getface obj 1
	f2 = getface obj 2
	format "  face1:%   face2:%\n" f1 f2
	
	n1 = getfacenormal obj 1
	n2 = getfacenormal obj 2
	format "normal1:% normal2:%\n" n1 n2
)

@Klvnk
At first glance I would think yes, the outer and inner edges goes in the direction you have described, but I can’t make a statement out of it.

turns out I’d didn’t need it, though it’s an interesting property if it is the case.