Get down with Rawrbots

Get down is a meme that has it’s origin in a glitch in GoldenEye for the N64 and we had something similar in Rawrbots. If you want a lesson in what Get Down is visit http://knowyourmeme.com/memes/get-down-????.

The problem occurs in Box2D when you have multiple revolute joints attached to a single body. The torque on that single body becomes so large that Box2D and it’s constraint solver don’t know what to do so it takes a vacation.

The result of the absence of the one in charge over physics can be seen here.

Browsing the web and asking our good friends Google and the Box2D forum we found three solutions.

1. Don’t let the players build their own physics, since that is what Rawrbots is all about this wasn’t possible.

2. Increase the weight of the body that have all joints attached to it. This sounded like the solution we were looking for, the only problem is that you can’t increase the weight of all bodies, only the “hubs”. So if we would have gone with this solution we would need to check which bodies had many joints attached to them and then increase their weight and that would lead to some odd mechanics.

3 . Increase the number of iterations that is sent to Box2D’s step-method (@param iterations, the number of iterations to be used by the constraint solver). By increasing the number of iterations you suffer some performance loss but you get a much better simulation.

The third solution is the one we went with and we cranked up the iterations so much the creators of Box2D must be crying but the performance didn’t suffer that much. You can still build Get Down Rawrbots if you play the game as it’s not intended to be played but we had to draw the line somewhere otherwise we would end up with a game that is running at 2 fps.

Leave a comment with your best Get Down Rawrbots!