For over a week I'm trying to find a bug in my raycasting engine. I followed F. Permadi tutorial and everything looks good except one thing - when player is facing south-west or south-east (angles between 180 and 360 deg) strange artifacts on walls can be spotted

[attachment=33753:aaa.png]

They are precisely at the beginning of each wall block, but after rendering few wall slices everything back to normal. Looks like for unknown reasons all these slices have equal distance but I have no idea why.

I would like to ask you for a help to find a fix for that.

Raycaster code can be found here: http://pastebin.com/BR3MLJKB