Question by Artanisx · Jan 15, 2021 at 09:52 AM · physics rigidbody.addforce calculations

How to calculate how much Force (ForceMode.Inpulse) to apply to reach a specific target transform in 3D space?

Hello!

I need to calculate how much Force to apply (ForceMode.Impulse) to a Rigidbody so that it will reach a target transform in 3D space.

Currently, what I do is calculate the direction from the object to the target transform:

         // Get the direction towards the target
         Vector3 direction = target.position - playerRB.position;

Then I add some upwards direction because I want for it to arc like it's a ball (well it IS a ball) launched in the air, as I don't want for the object to go to a straight line:

     // Normalize the Direction vector
     direction.Normalize();

     // Add some UP movement
     direction = direction + Vector3.up;

And finally, I try to calculate how much force to apply accounting for the Distance between the two objects, but here it's mostly guesswork and it doesn't really work often (I save this calculated value in a float called forceToBeApplied).

Afterwards I launch the object:

     // Add force to the ball (Launch)
     playerRB.AddForce(direction * forceToBeApplied, ForceMode.Impulse);

Alas, as I mentioned, the forceToBeApplied float is hacky and the results are not always the intended ones.

How can I calculate that float so that the rigidbody reaches the intended target? I assume we need to consider the world gravity, the rigidbody drag and the angularDrag.

Any help will be appreciated :-)

Thanks!

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