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Skin modifier crashes Blender
Open, Confirmed, MediumPublic

Description

Windows 10

Blender 2.79a 8928d99270f

Adding the skin modifier to the stack, after boolean modifier with Union and the BMesh solver, crashes blender. (if the solver is Carve, blender doesn't crash)

Have a cube, then have another cube. Unite these cubes with the boolean modifier (the operation has to be Union) the solver has to be BMesh then add the skin modifier to the stack; and then blender will crash.

Details

Type
Bug

Event Timeline

LazyDodo (LazyDodo) triaged this task as Confirmed, Medium priority.

can confirm the issue on latest master.

to make repro easier, open file, add skin modifier.

@Campbell Barton (campbellbarton) do i need to add this to T47030 ?

(Disclaimer: I'm completely new to Blender dev, and I randomly picked this bug to have a look at to try to figure out the code. I've *think* I've tracked it to a certain point, described below, but please use caution when trusting what I say...)

This seems to be caused by the boolean modifier creating a DerivedMesh with a vertData layer of type CD_MVERT_SKIN, but with the radius set to 0 (or actually just never filled in). I've so far failed to find out where that should actually get filled in.

This causes a whole bunch of NAN's to be spat out into the vertex data of the convex hulls of the Skin modifier.

Hope that's helpful! Apologies if it's wrong/obvious.