Generate Complex Blues
GenerateComplex is a very unique tool dealing with a situation which isn't allowed in most CAD apps: Internally it deals with non manifold triangles. Plus (considering MM's history), it's a new tool - there ARE issues I'm aware of (especially if one splits the resulting complex) generating complexes based on the face group's boundaries:
- if there are more than one group boundaries (ore even more) connected to the same 2nd group doesn't work. E.g. something like (the green group meets the white one twice):
Instead if you split the white group into two like this:
GenerateComplex (and splitting it) will do it's job(in most cases)...
Also: A group's boundary needs to touch a single neighbour group. E.g. this will NOT work:
for the green group's left boundary is in contact with two groups.
Another issue may be low-poly models (as you might get on export from BRep CAD apps). You'll may run into problems if a single triangle face reaches from one to another group boundary.
Accepted solution
Argh - that's bad meshing.
There are tons of internal faces connecting the outer surface through the object:
E.g if you cut off one shoe it looks like:
You need to get rid off these issue before trying to generate some complex.
Whenever you import a mesh from a third party source you should run some checking analysis:
- Hit W to watch the wireframe: Is it a low poly mesh with long stretched triangles? (in your case: That's ok for the outer surface)
- Is the object composed by not connected shells? Try EDIT/Separate (in your case: That gives one particle object which is that small that you can't see it.) Delete not needed objects.
- turn the object transparent (e.g by hiding it while it is the active object, or using the Transparent SHADER).
- run ANALYSIS/Inspector to check whether MM finds some issues to repair.
Doing this you will understand the mesh's quality and give you some hint what you need to do.
Now with the given mesh GenerateComplex will not work properly.
Try EDIT/MakeSolid at SolidType = SharpEdgePreserve to get rid of those internal faces while keeping sharp edges . You'll need a high SolidAccuracy and MeshDensity (Note: That will increase the file size and therefor the load you machine has to handle). Hit the Update button (this is very slow so go for a coffee !). If you're satisfied with the result Accept.
After you made the mesh a solid (watertight outer shell) it's time to get working face groups.
As a rough start run EDIT/GenerateFaceGroups.
Set its SizeTheshold to max to avoid tiny groups. A AngleThreshold at 13 gives the best grouping in this case here:
That's a raw grouping only. As you see at the hair or shoes there are still tiny groups but others are perfect.
Select the main group you want to split off. E.g:
Check this selection for missed islands or missed/not needed faces at the boundary. Add or remove such faces using a small brush.
When done run Modify/CreateFaceGroup.
Now select the regions of that group again and hit I to invert the selection:
Again run Modify/CreateFaceGroup on that selection.
Now we ended in two groups only. But we made sure that each face is either group A or B and there's no missed face.
As I tried to explain in a previous post GenerateComplex only works if one group is connected to another group on a single, closed loop.
So we need to split the groups again. In SELECT select a region of a group by double click and run Modify/CreateFaceGroup on it. Do this for each region until each group touches another group one time only:
Now going to EDIT/GenerateComlex shows all the seams:
Hitting AutoGenerate now inserts parting surfaces for each loop with a single click:
Accepting and splitting the complex gives this result:
Note the result at the eyes. Here is a ugly intersection. That's due to the definition of the groups there. I could go back and redefine these groups or go back to the GenerateComplex step and use offset of groups instead of fill boundary loops for these cases.
