I’m sorry for the delay.
I use scaling to make camera effect. I cannot find any other way make camera in corona.
All physics objects are in one group (map) and it shouldn’t cause any problems, as I know.
Thick lines appears because oulines cannot be smaller than 1 px. Scaling is too big and this 1px lines drawing as thick lines.
All physics bugs exists only with rectangle character. Circle player works perfectly.
I have the same bug (sphere works good, rect not)
https://www.youtube.com/watch?v=1JKBJJx8wLE&feature=youtu.be
As you can see box shape is big enough to collide normally, and I mean it’s big enough to make i.e. floating platform. Bad idea. Some collision precision option must be grown in settings. Screen resolution is HD 1280x720.
As you can see I have simple polygon here colliding with simple rect. In both cases height or radius are equal = 8