Box2d：动态物体未完全与运动物体接触

Question

I'm building a simple platformer game based on box2d.

Player is made as ChainShape dynamic polygon object with two sensors (bottom and top).

Floor object is a simple kinematic box.

Problem is that for some reason, player body never fully fall down on the floor body - there is always several pixels between them, making player sprite to look like it is flying above the floor and not standing on it.

Here is a couple of enlarged screenshots: 1) player jumping (body looks fine):

2) player is standing on the floor (something appears at the bottom of player's body and prevents it from contacting with the floor):

Kinematic bodies contact with the floor correctly.

What can be the problem?

Answer 1

I found an answer here http://www.iforce2d.net/b2dtut/gotchas#smallgap

I had 250pixels per box2d unit, so 0.005 of that equals 1.25pixels. Additionally to that it seems that this linearSlope comes from both fixtures, eventually resulting in 2-3 pixel gap.

After changing the world (I had to make 250 pixels to be 5 units, increase gravity 5 times and increase all horizontal velocities also 5 times to get the same game feeling as it was) problem seems to be resolved.