Hi NightCabbage, just some more details on this part:

> For example, I just imported a .lwo file, with some flat surfaces
> from moi, and half of them were back to front (backfacing).

By flat surfaces you mean some planes that are non-solid open surfaces?

Those will not necessarily have any one fixed orientation for their normals - it will depend on things like whether you drew some of their construction curves clockwise or counter-clockwise or things like that.

Unlike a solid, an open surface all by itself just does not have any automatic "correct" orientation to it.

Here's an example - say you draw a vertical plane like this:




If it just stays as an independent isolated surface like that, there isn't any way for MoI to know whether it is supposed to be the front part of an object like this:



or whether it is supposed to be the back part of an object like this:




This is not unique to MoI or even NURBS surfaces - if you build objects in a poly modeler one individual polygon at a time you will run into the same thing.


But in MoI if you join all the individual surfaces that touch each other like that into a completely closed solid, then there is a well defined inside and outside to an object like that and all the surface normals will automatically get oriented towards the outside of the solid object.


If you are not making a full solid, then you can either flip the output in your polygon modeling program, or you can also set up a keyboard shortcut with the Flip command in MoI which you can run on an open surface object in MoI to flip which side is considered to be the positive surface normal side.


In the future I want to add a kind of "direction showing mode" that would show the negative surface side of the object in MoI in red so that you could more easily see which side was which. Right now there isn't anything for that, mostly because there isn't really anything in MoI itself that is particularly sensitive to that.


- Michael