Hi All,

We are using MOI to export very heavy models to Modo via .obj. Most of the parts come fine but sometimes we see cases where the vertex maps make the parts look completely black in Modo or mostly black with bubbles/splotches of the material color assigned. This is always on parts that are not closed solids and have flipped normal. In Rhino we can see the flipped normals with a custom color for backfaces, but if we want to take Step files to Modo via MOi's mesher and skip a Rhino stop, we never know this. Does anybody have a good workaround for this?

Thanks,

Hi gustavo, there is not currently a way to visually see which side MoI is considering the "outside" direction of a surface object that is not a closed solid. Some kind of display for that is something that I want to add in the future. It hasn't been done yet because the modeling operations in MoI are pretty much set up to avoid being sensitive to that.

If you do know you have an object that needs flipping, there is a Flip command in MoI that you can set up on a shortcut key to flip the particular object.


Do you only render with single-sided materials? Does the blackness go away if you use double-sided lighting in the material?


One thing that's a bit odd is getting a splotchy result - is it possible that there are 2 objects stacked up right on top of each other in those situations?


Another thing to be careful of is that you can get the vertex maps out of sync with the geometry if you do some things in Modo like if you transform the object while not in "item" mode. That can do stuff like transform all the vertices of the object but it won't update the vertex normal map when not in item mode so the normals are out of sync with the object when that happens.

Is it possible that some of the problem objects were transformed in Modo while not in item mode?

- Michael

Hi gustavo, the other reason why there isn't a "backface" type display in MoI is that for a long time I assumed that could be done in a polygon modeling program, since every polygon modeling program seems to have a flip function in it.

Unfortunately many of them seem to be broken when flipping meshes with vertex normal data attached to them. Is that still a problem in Modo now?

Could you ask them to fix that up? It's a pretty simple thing - if you flip a mesh that has vertex normals, it should flip the vertex normals as well.

- Michael

thanks Michael, I will ask, and let you know if this gets fixed on their end.

Have you tried : Geometry-> Vertex -> Merge...
Not the "Merge Tool".
You may need to run the tool a second time.



Also, if there are any left(There are usually no left-overs if I use LWO format for export):
1 - In polygon mode, with nothing selected: press F two times( I don't know why this works, but it does).
2 - Polygon-> Align.
3 - Sometimes there are still strays left over, in this case you must flip them individually(even if their normal is facing outwards) and apply Polygon -> Align