Texture painting problem with particular object

This problem has been driving me crazy for two days and I can’t figure it out. I think I’ve ruled out a Blender bug…I’ve been using 2.82 and I tested the issue with another object and it works ok.

Here’s the issue…

This is a just a dummy texture I made to show the problem. By the way, this happens regardless of whether I use a single UV tile or UDIMS. It happens whether or not I use the original UV map from the imported OBJ, or create a new one.

When painting on the object, everything is OK when first opening the scene. If switch from texture paint mode to edit mode, then back again I either can’t paint in the spot the brush is or I get jagged poly imprints and colors in the wrong spots. It just looks like a mess. Zooming in and out will make the look change, but it still looks like crap. If you look at the UV map, the texture looks good. It’s just the way it draws in the viewport that looks weird.

I tested with another imported OBJ and it works fine. I would love to avoid retopologizing this object. Can anyone think of a reason that an object would make painting such a pain? One other thing I’ll mention is that Blender gets very sluggish when the problem starts happening during painting. My GPU and CPU fans go into overdrive and everything slows down. It only happens with this object.

Of course, an option to fix this problem is to NOT switch to edit mode during painting, unless I want to restart Blender…but I’d like to understand what’s going on. I also have the suspicion something is wrong with the model.

Is it only switching to edit that does it? Or are you doing something in edit? Something as simple as hiding or unhiding verts?

If you’re sure you’re not doing anything in edit, I would be looking for any texture painting settings changing on switch/switch back.

I found a fix…if I select all of the skin polygons and “separate” to a new object, I can now paint on it properly. Maybe it has something to do with all of the little unconnected pieces like the teeth, tongue, etc.

Will investigate further.

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If such problems arise I try the following: export the object and reimport it (try different export formats). However, you should only use beta versions for testing. :wink:

That didn’t work…but thanks for the suggestion.

Ok I think I’ve found the final solution to this problem. I checked the polys using the “mesh analysis” feature in the viewport options and found a bunch of non planar polygons. They’re mostly that way because in many cases I like to distort polys to extreme non planar positions to get the details I want, as opposed to making new edge loops, etc. Once I shifted the majority of the red polygons to be more “safe”, there’s no weird painting artifacts when switching between modes.

By the way, that mesh analysis is one of the coolest things I’ve ever seen in a 3D software. I never had access to that kind of detail in Softimage.