Accelerating rotation by difference in direction | Official Unity Discord | Page 1

pure coral Jul 17, 2025, 7:16 AM

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I am attempting to rotate an entity with physics via adjustment of PhysicsVelocity.Angular in order to gradually point the entity in a direction (in this case the direction it is wanting to accelerate in) but cant figure out how to get the amount i wish to adjust angular velocity by to rotate it in the right direction, all i have managed to do thus far is make a spinner. (i know barely anything about vectors and quaternions)

cyan crown Jul 18, 2025, 8:45 PM

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I wonder if a PID solver will help you? I've done something similar in my project to get the exact angular velocity I need. You might also be able to lerp between current rotation and a target rotation if you only need someting simple

pure coral Jul 20, 2025, 4:02 AM

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sadly, lerp is not enough
but im just not sure how to get it rotating the correct way

mighty marten Jul 20, 2025, 12:23 PM

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~~are you using a spherical lerp?~~nvm im hallucinating

pure coral Jul 20, 2025, 7:48 PM

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   Vector3 unitEuler = unitRotation.eulerAngles;

   float3 differenceR = (unitEuler-new Vector3(180, 180, 180)) + (targetRotation.eulerAngles - new Vector3(180, 180, 180));

   float3 rotForce = math.clamp(differenceR, -maxRot, maxRot);

   angularVelocity += rotForce; //rotationalThrust;

   physicsVelocity.Angular = angularVelocity;

this is what my latest attempt looks like (but it just turns into a infinitely accelerating spinner)
i know using euler isint optimal, but i have even less of an idea on how to properly use quaternions for this

mighty marten Jul 20, 2025, 9:32 PM

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what about something like this?

var diffRotation = Time.fixedDeltaTime * math.mul(math.inverse(unitRotation), targetRotation); // maybe flip the multiplication order, I always forget
physicsVelocity.Angular = math.Euler(diffRotation);

pure coral Jul 21, 2025, 12:45 AM

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yeah, thats works, though it looks like i will need a predictive element aswell

mighty marten Jul 21, 2025, 7:49 AM

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predictive?

pure coral Jul 21, 2025, 9:18 PM

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just something to stop it from rotating too much and overshooting (because i want the rotational force to be small but additive)

mighty marten Jul 22, 2025, 8:07 AM

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ah, i didnt expect it to overshoot actually, but I'm sure you can figure it out
you are changing this physics angular velocity in the fixed update right?

pure coral Jul 22, 2025, 9:11 AM

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Yes, its just overshooting because im making it add an amount to velocity each update

mighty marten Jul 23, 2025, 8:05 AM

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yeah though my example will add less if the difference is less, so I didn't expect it to really overshoot

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anyway soudns like you got it working 👍

#Accelerating rotation by difference in direction