Hi Shane,

> Is it possible to have the back faces in MOI shade a different
> color? It would be very useful to see the surface normal direction
> in MOI and correct the reversed faces before exporting as an
> .obj for rendering.
>
> If not currently possible would this be a possible addition in
> the future?

There is not currently any way to do that in MoI, but it is something that I want to add in the future, it's been on my todo list for a while.

Right now the easiest thing to do is to just enable 2-sided shading in your rendering program - that way your object will be rendered properly no matter which side of the object happens to be the positive surface normal direction and then you don't need to worry about the orientation any more at all.

Also if you make your object into a fully closed solid in MoI before exporting it, that will automatically orient the surface normals to the outside of the solid volume when the mesh is generated for it.

- Michael

Hi Mike,

> Michael, I think this would be an easier feature to employ
> by building the capability to view the reverse sides when
> in the export to poly's dialog.

I've thought some about doing it at that stage before, but one issue with that is should the flip be done just for that one export only? If so then what if you want to do several exports in a row, say with different resolutions or with new objects added or whatever - would you then need to redo the flipping on each export?

Or would the flipping at export time stick and actually edit the object? If so then that's also kind of conceptually a bit weird to be editing the model in some way as part of the export - it's somewhat unusual for the base data to be edited as part of a export process.

So that's why it may end up as a separate command or display mode.

Anyway, that bit of uncertainty about how to best set this up is one reason why it hasn't been implemented quite yet.

- Michael

Then in that case, it would work better universally to implement this in the UI.

As to how... does the DirectX draw allow for the rendering of polys with separately colored sides?

I think I remember seeing in Rhino, that they achieved the same effect by showing little hash lines emanating from the middle and normal face with a little arrow.
That can be drawn in and out as the temporary construction lines behave.

A check switch in the option's view section could suffice to activate this demarcation feature.
Therefore, we can leave it to the designer to choose which surfaces to "correct" by selecting and Flipping.

Hi Mike,

> As to how... does the DirectX draw allow for the
> rendering of polys with separately colored sides?

It's not a "built in" feature of DirectX that can just be turned on with a single switch, but it's still possible to do it either by making 2 display passes (one for front faces and one for back faces) or by using a shader.

That part is not really the issue - it's more about figuring out the UI for it.


> I think I remember seeing in Rhino, that they achieved
> the same effect by showing little hash lines emanating
> from the middle and normal face with a little arrow.

Yeah, I set it up that way in Rhino because Rhino was primarily designed to work in wireframe display mode where there isn't any shading going on at all.


> A check switch in the option's view section could suffice to
> activate this demarcation feature.

Yeah, that's kind of another still open question - whether it should just be a display mode that you can turn on or off and then have a pretty simple flip command that just flips things and doesn't do anything else, or whether the flip command should be a little beefier and temporarily turn on that kind of display and then let you click on things you want to flip rather than working on preselected objects like it does right now.

- Michael

I would like it as just a simple view option or view mode. You could switch on colored back faces, flip the needed surfaces then click it off. I think in most cases I would just work in that mode. I feel an elaborate flip command with colored back faces is getting a bit too specialized.

Thanks,

Shane

Yes, if you can see the reverse faces, then you can select them and Flip them at will to suit.