Hello.
I'd like to set up collisions for my game in such a way that if you were to push up against a wall at an angle your avatar would slide along the wall … if you get my meaning. Right now you just stop entirely - and it can be awkward navigating small spaces as if you bash into a wall you'll often have to backup and turn around.
I was just wondering if anyone had some insight into how this would be done. I was thinking about firing a ray off at an angle to the left and right of a player and working out … something … I haven't thought it through so much but I figured there might be a better way than whatever-it-is that I'm thinking but can't put into words. 
Well I use jbullet for the player movement.
I have a similar issue right now in fact, so glad you brought this up.
My suggestion (but I haven't tried it yet) is to break the movement up in to two pieces. The forward/backward, and the left/right. Do collision checks for forwards/backwards (and move if allowed). Then do a collision check for the left/right (and again move if allowed).
Let me see if I can get an implementation working on this…
You can do the shoot the ray thing (calc strike angle to offset player movement) but its probably easier to use a physics package. I have used the simple physics package noted in this thread for wall sliding:
http://www.jmonkeyengine.com/forum/index.php?topic=5073
And here's a webstart demo of it in action (in a "lab/test" area):
http://www.jmonkeyengine.com/forum/index.php?topic=5073.msg80483#msg80483
Its not too tricky to set up.
@Ashtonov,
you use JME1, right? Or did you port SimplePhyiscs successfully to jme2?
Regards,
snare
mcbeth ported it to jME 2 and that's what I used for the lab/demo stuff.
Come to think of it, I don't think that it ever got a permenent link on the website or forum. I think he pm'd an url to me that had the code.
mcbeth: are you out there? Can you post it or point to the link?
If he's not out there then I can put something together and post it… but it might be a few days before I have any real time to do that.
The math isn't all that hard, so if you are not already using a physics package then just do it all using jME.
http://www.jmonkeyengine.com/forum/index.php?topic=4031.msg32166#msg32166