Adding multiple forces at different rates.

Unity Engine
1

So I have an object (crate) that I want to move around on top of another object (ship).

I want the crate to accelerate up to (desiredVelocity - velocity), moving it across the ship’s deck.

I also want to add the ship’s velocity to the crate, so it will move along with the ship.

Right now I’m using this:

Vector3 velocityChange (desiredVelocity + shipVelocity - velocity);

rigidbody.AddForce(velocityChange,ForceMode.Acceleration);

This works, but it has to accelerate up to shipVelocity. So when the ship starts moving, there’s some lag time before the crate starts moving. I decided to try ForceMode.Impulse, and that adds the ship’s velocity instantly, but also makes the crate accelerate to desiredVelocity instantly.

So I’ve tried doing (desiredVelocity - velocity)*Time.deltaTime + (shipVelocity - velocity), with impulse mode, and it accelerates right, but shipVelocity is added waaaay too much.

I know I’m probably missing something really simple like I usually do. Might someone else have an idea about how to do this?

2

Just a guess:

Vector3 velocityChange (desiredVelocity - velocity);
rigidbody.AddForce(velocityChange,ForceMode.Acceleration);

rigidbody.AddForce(shipVelocity-velocity,ForceMode.Impulse);