Why is my 2D arm mesh twisting wierd?

Question

So I imported a PNG of Peppa Pig as plane and edited it as a 2D mesh directly. Being a newbie, of course, I fxxked up hard.

You can tell by both the weight map and render view how screwed I was. The weight distribution was going coco and the texture went wild. I assume that this is because my mesh was simply just bad, but I can hardly find any suggestion on making a proper 2D mesh, so any suggestion about this messy situation of mine will be really appreciated.

Here is my .blend file.

BTW, just in case if you are wondering why can't I just seperate the forearm and upperarm and hand: my boss asked me to deal with it as a whole, hence I have to deal with it.

Answer 1

Right - bad topology ... what you see in your first image is z-fighting (overlapping two faces).

Find this whole hand face

And delete. It should be OK.

Since your triangulated hands has no UV, select hands vertices go to front view and Unwrap from View (U). Switch to UV Editing layout and reposition uv on image.

... or you can go an opposite way - delete triangulated hands and keep the one-face version and search for Triangulate Faces (Ctrl/Cmd+F) operator. Since this is unwrapped and weight painted you don't have to do do noting more.

Answer 2

The reason your arm is twisting wierd really comes down to two things:

1. your mesh is not dense enough (it needs more detail to be able to deform well. You can most often accomplish this by adding a modifier > subdivision surface.

2. You have attempted to apply a human rig (To my understanding) to peppa. In this rig are multiple bones which are redundant and are highly likely to cause errors. You will need create a custom rig for peppa to deform correctly.

I did attempt to fix peppa, but encountered a crazy amount of problems. I won't go into it, but heres sort of where I got up to:

So, what is the next step for you? I highly recommend you learn how use blender to an intermediate level in 3D before attempting to use Blender's 3D tool to work with 2D artwork. Learning 3D first will fill in a huge amount of unknowns about how the software works and allow you to work without error in 2D from that point on.