[x3d-public] Extrusions, take 3 - no spine direction

[Alekseyev, Vsevolod (NIH/NIAID) [E]]

>> 2) When the spine goes (0,0,0)-(0,1,0)-(0,0,0), what is the CSP?

> First a flaw in the specification prose above:
>	"If two points are coincident, they both have the same SCP."
> is better expressed by something like
>	"If two sequential points in a spine array are coincident, they both have the same SCP."
>If we think the case you give can be generalized into a special-case definition, we should provide one.  Otherwise it should be covered in the degenerate definition.

The problem is not that the points are coincident. The problem is that the *spine direction* for the purposes of the "rotate the Y" rule is not well defined here. The spine is clearly collinear, but what is its direction?