The bug

When falling from a height onto some blocks, there appears to be a noticeable directional bias in the direction in which the particles are generated.

How to reproduce

1. Place a door
2. Get on top of it
3. Align yourself as best you can in the middle of the three pixels while at an edge
4. Fly high up without moving horizontally
5. Now fall back down

Expected results

The particles would be generated at the center, where the player is. Since the player is in the middle of the three pixels on one axis, there would be no need to round the particle generation position on that axis.

Actual results

They appear to be shifted to the side by some factor which is visually noticeable.