Box2D Forums

Anyone ever have this issue? My conveyor belts have started going backwards. This has never started happening on my machine, but it has happened twice now when the other designer/developer working on my game levels has been doing edits. Once he saves his level and commits it to SVN, then I've got the problem as well from that point forward.

So, the only fix we've found is to find a level where they don't go backwards and paste the old belts back in... Now, it appears that the deferred creation of my Avatar(BoxMan) is causing this... it only happens to the character, not other objects.

I'm sort of stumped. We can currently fix it be not doing a deferred creation of the Avatar, but the purpose for doing that is so the player can enter and leave the level from different points. If I try to position a "live" character, he gets that offset in velocity and flies out of the level. The deferred creation was my solution to position him, then "create()" him.

Thank you in advance.

Actually, I've noticed conveyor belts sometimes have a sinusoidal motion... i have pieces that are supposed to go from conveyor belt to conveyor belt (often with a falling motion). Some of them will hit a conveyor belt and then start reversing directions.

I'm starting to think I need to look at rolling my own solution or do a lot more digging into the code and see if I can find out what is amiss.

I see, mayo, that you've had this problem all along... If you have any hack solutions that come to mind let me know.
viewtopic.php?f=3&t=5413&p=25281&hilit=conveyor#p25281

I think the solution we're going to go with, because we're n00bs and can't think of anything smarter at the current time is as follows:
we have to conveyor belts. One doesn't collide with "blacklisted objects". It has a conveyor belt speed of -3 (left). The other ONLY allows blacklisted objects to collide and has a speed of 3. This allows both sets of objects to go the correct direction (at least the one we want it to be)

I'm just replying to say I have not found a solution to this. I agree it's kind of infuriating. Maybe BodyShapes can have a flag "reverseConveyorBelts" that cause that cause the effect to be multiplied by -1. I get the impression from your post it happens to the same objects every simulation? I wonder if conveyorBelt-to-conveyorBelt the effect is reversed for a particular body, or if it's only reversed for particular belts.

I'm not sure. I do know that the act of creating a shape after the level is up and running, as I do with my main player character, seems to make it reliably backwards for that physics object. The other ones, they tend to get their behavior rattled by transferring from one conveyor belt onto another.

The effect I'm going for is an autonomous factory that the player happens upon. Pieces sort of travel along a system and then get collected, destroyed and recreated at the start of the system. I definitely want to share those components when I am able to.

You might try following up with Erin. I just tried to implement this, and they seem to behave very randomly.