Dynamic gear engagement

The engagement between gears is now activated and deactivated dynamically.  This means (as the various parts of a construction move around) gears will engage if they move close enough to each other, and disengage if they move apart.  The test that checks if a pair of gears are engaged is fairly expensive, and obviously I now have to do these tests every update.  So to avoid doing this between every pair of gears in a construction (i.e. O(N^2), not good), I use trigger volumes around each gear to find pairs of gears that are close to each other, and then do the engagement check only on these.

New steering wheel part

I’ve added a steering wheel part to the game that attaches to axles.  It has a behaviour similar to the motor, where if “switched on” it will rotate in response to user input (i.e. the usual hold shift + directional controls).

Its obvious application is as a vehicle steering wheel, but more generally it can be used as a “control wheel” anywhere you want to rotate bits of your construction in response to user input.