Box2D Forums

From the pom.xml file I find "version: 2.1.2.1".
I also use Fizzy wrapper, so creating the bodies is a little easier. I hope you don't blame Fizzy, since the wrapper is so simple that I don't think it's causing the bug. Well, I could be wrong.

Here's why I think the body's reference point has something to do with the bug:
When I create a body using the coordinates {9.6 , 2.5} , {10.0 , 2.5} , {10.0 , 10.0} , {9.6 , 10.0} with a reference point 0,0
I get the bug.
But when I use coordinates {-0.2 , -3.75} , {0.2 , -3.75} , {0.2 , 3.75} , {-0.2 , 3.75} with the reference point at 9.8 , 6.25
the bug disappears. Now the reference point (the body's origin) is at the center of the body. The body is still at the same location, with the same measurements. You can double-check the coordinates.

EDIT:
okay, just found out the bug occurs only when a box (rectangle) collides with the wall. Circles collide correctly.

The problem might be in JBox2D, since the world's physics update in Fizzy calls only two methods:

This means that Fizzy has nothing to do with the actual physics simulation. Now, this could mean that either there is a bug in JBox2D, or Fizzy gives some crazy values for the jbox bodies. What do you guys think?

I had a problem like this when my polygon shapes were not ordered right (points in wrong order)
things teleported through them. If you make a dynamic box shape for the character and static / 0 density box shape walls you shouldn't have a problem.
Try make everything dynamic out of boxes and circles (add multiple box/circle shapes to 1 body if you want), and use 0 density box shape/circle shapes or edge shapes for static stuff. Works for me.

Definitely check out the latest version (2.1.2.2), it fixed one of my bugs.
And try not using that wrapper. Make your own

The problem will be in the creation of the shape, not the simulation (update) method

Okay, maybe I should study more on how JBox2D works, and then build my own wrapper.

Yes, please use the 2.1.2.2 version, it will probably fix this. I should make an official 2.1.2.2 release soon