I've been working on a mod for a while, and for it I modified EntityArrow to do a bunch of things, but now I seem to have hit a bug that I can't seem to squash.

I made a MovingObjectPosition field called lastHitMOP in it that, when not null, will make onUpdate do the hit code (damaging a living entity or seting inGround true). However, it seems that the hitVec value in it gets set to 0, 0, 0 after a few ticks (it doesn't always seem to happen, it's rather unpredictable), and I have no idea why. I also tried making the hit vector be three double fields instead, but they seemed to get reset too. Here's a pastebin of EntityArrow.java:

 

http://pastebin.com/B7sUcKq4

 

lastHitMOP is set on line 1067. The hit code begins on line 737.

 

Example debug output:

2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT pre -12.461743733321669, 70.04916143532088, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT afterSetPrevMOP -12.461743733321669, 70.04916143532088, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT endrealtick -12.461743733321669, 70.04916143532088, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER pre -12.45898904572035, 70.08384683688837, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER afterSetPrevMOP -12.45898904572035, 70.08384683688837, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER endrealtick -12.45898904572035, 70.08384683688837, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER endrealtick -12.45898904572035, 70.08384683688837, 260.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT endrealtick 0.0, 0.0, 0.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER endrealtick 0.0, 0.0, 0.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT endrealtick -12.0, 68.0, 255.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER endrealtick 0.0, 0.0, 0.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT endrealtick -0.093770332634449, 0.24353814125061035, 0.9653477072715759
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER endrealtick 0.0, 0.0, 0.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT endrealtick -0.093770332634449, 0.24353814125061035, 0.9653477072715759
2013-05-03 13:32:51 [iNFO] [sTDOUT] CLIENT calculations 0.0, 0.0, 0.0
2013-05-03 13:32:51 [iNFO] [sTDOUT] SERVER calculations 0.0, 0.0, 0.0

 

Anyone have any ideas why it's happening?

I made hit vector position fields and made it re-set the hitVec to their values and now it's working... perhaps not the best solution, but at least it's working now.