1st. what known bugs are causing you problems as of 4.12.4 —
So far the problems I have had have existed since I started with vehicles in 4.6: The physics bodies of the vehicles have a lot of artifacts when interacting with other physics bodies, and particularly character movement capsules. I got around this by always protecting the vehicles physics bodies with an external collision body I add in later and flag “ignore vehicle”
A big problem which causes me to have to spend a lot of extra time in level creation is when the physx wheels clip over a protruding piece of collision, like say a rock or a short post, the sudden change in height can cause the physx to react sharply and potentially flip the vehicle, this happens a lot when turning into the object and hitting it from the side. I have to spend a lot of time going over every part of the map and either setting collision on objects to ignore vehicle, or putting in tall vehicle blocking volumes to prevent the vehicle stepping up on the object.
The gearbox, the current gearbox only allows for gear shifts based on RPM, as it stands if you have a vehicle trying to climb a hill it will shift up, lag, then shift down, and repeat. This only happens when climbing hills, the gearbox won’t sit in a gear and crawl. I have made a custom gearbox that shifts based on speed, but it is far from perfect.
The engine torque, as it is right now, the engine does not lose RPM when shifting up a gear, it seems to operate more like an electric motor with a brief lag between gear shifts, this is more common in heavy vehicles with slow top speeds and higher gear ratios.
Also wall riding still happens, vehicles don’t like to roll over unless the wheels have already broken contact with the surface for other reasons (jump, fall)
A bug with the replication - the vehicle shuddering left and right when moving at speed, I think it may have to do with location updates in the networking.
Super heavy vehicles - setting the vehicle weight to anything over say 10, 000 and the vehicle just does not operate well at all.
2nd. how do you want to make your vehicle ‘engine side’ eg using a ‘wizard’ / base blueprint with add on components / base code with as much open as posible / other ideas — **
I like the way everything is set up as it is, you can use external curves for the engine torque, it just all needs a bit more tuning especially with load and gear shifts.
**3nd. how important is realisum to you eg. control variables/physics — **
Realism is nice, however too much realism is expensive performance wise, I like a balance, I just think the obvious unrealistic results of crashing or flipping a vehicle should be fixed.
4nd. what sort of vehicles do you want to create —
I have created 2wd, 4wd, 8wd, half tracks and tanks, this is mainly the stuff I work with, however motorbikes would be awesome one day, I have attempted but the results were not very good.
Some things I have yearned for in the UE4 vehicle is to have “contact surface” from the debug exposed to BP so we can change effects etc based on the physmat the vehicle is on, and also for some basic skidding or slip detection in built in (might be there already and I goofed)
All in all I am pretty happy with the vehicles in unreal, there are some obvious bugs that need to go, but I think the system offers quite a lot considering how difficult vehicles can be!