Hello, I am writing a custom modifier (inheriting from Modifier) that adds topology (extending the borders), and whenever I am below it on modifier stack with “show end result” enabled and manipulate elements (move/scale/rotate) in any subobject level it crashes. I have tested ChannelsUsed and ChannelsChanged with ALL_CHANNELS and GEOM_CHANNEL | TOPO_CHANNEL but the problem insists. I also tried the NotifyInputChanged but no luck. Any thoughts, what am I missing?
Custom modifier crashes
har1sf0x
#3
I hope the attached picture and video somehow help you @Klvnk help me because my experience in c++ and max sdk is not extended. Trying to find my way reading and studying the howto, samples and online reference.
har1sf0x
#5
Unfortunately not, I did not manage to get a copy of the mesh as MNMesh in order to operate and copy back, and the effect every time it was evaluated it was stacking. I am using Mesh but when I try to edit interactively it crashes. Actually since the last time we “spoke” I managed to operate with end result enabled but it needs to reenable or change the subobject level in order to update. I used NotifyInputChanged and a custom LocalModData. The issue is that when the editing is stopped it does not emmit something. Should a mouse callback be implemented? It seamed in the sample extrude.cpp much simpler, since you can manipulate interactively e.g. a spline, below the modifier.
TestExtendModLocalData* hs = static_cast<TestExtendModLocalData*>(mc->localData);
if ((int)partID == 134) hs->Invalidate(); //TODO(“check which partID results in int-134”)
if ((int)partID != 134) hs->SetValid(changeInt);
ed.: And I just realised that there is a general issue with editable_mesh and returning to the modifier after being just below the modifier on stack. 
ed2.: TheHold seams to be the answer, need to run more tests before committing to be the answer.