Most Efficient Method for Steering for Vehicle AI

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Hi Unity Community!

Any tutorial regarding vehicle AI gives the following code for getting the steering magnitude (-1 to 1) to the next waypoint:

 Vector3 pos = transform.InverseTransformPoint(nextWaypoint.position);
 steerMagnitude = pos.x / pos.magnitude;

But since this involves the Sqrt operation, is there a more efficient method? Because I plan on having about minimum 50 vehicles in the scene at a time. But that can even increase to 100 - 200 vehicles. Or is the Sqrt operation fast enough for mobile devices to cope with 200 vehicles using this code each FixedUpdate? I also have other code like OA, etc.

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Answer by tanoshimi · Dec 16, 2014 at 02:15 PM

What's your fixed timestep? I think the default is 0.02, but there's no way when I'm driving I adjust by steering 50 times a second.... if you need to keep the timestep that high for other calculations, then don't recalculate the steering magnitude in every FixedUpdate() - put it in a coroutine, say, that runs less frequently.

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EvilTak · Dec 16, 2014 at 02:32 PM 0

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That's a good idea. I'll try that later. Is there any limit for the number of coroutines running simultaneously? Do a lot of coroutines running together have an impact on performance? Since I have a lot of coroutines running forever (but waiting for few seconds after two-three statements) in my other code also.

tanoshimi · Dec 16, 2014 at 04:18 PM 1

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Coroutines don't run "together" - they still run on the main thread, but since they remember their internal state and resume from where they got to after each yield, they allow you to spread calculations over several frames.

Most Efficient Method for Steering for Vehicle AI

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