Difference between Launch character, Add impulse, and Add force?

Development Character & Animation
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1

Can anyone tell me the difference between:

  • Launch character
  • Add angular impulse
  • Add impulse
  • Add radial force
  • Add force

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2

Anyone know what the differences are?

3

Yep.

But i’m not going to read the documentation to you. You should search for it, and take the time to read it for yourself.

Start here: Physics | Unreal Engine Documentation

4

Pretty much as per above. Read the documentation, that’s what it’s there for. If you get stuck on a specific problem or use case - come back and post another question.

5

Documentation does not help in this case. I understand what force is but adding impulse and launching a character seems to do the same thing and there’s nothing in the documentation that I’ve seen that disproves this.

6

Each has a different use case. Launch character is only available to Character Blueprints. If you attempt to launch a pawn it will not work. Others are physics actions, each has a specific use case. For example if you were simulating an anti gravity field, you might choose to use Add Radial Force. An explosion would probably be best simulated by Add Impulse, etc

7

Impulse vs Force

AddImpulse will apply the force vector without adjusting for frames per second (fps). AddForce adjusts the force vector according to the current fps as it is intended to be called every frame. For example, if your frame rate were 60 fps and you called AddForce once then you would have to multiply the force vector by 60 (or call AddForce 60 times) in order to get the equivalent effect as calling AddImpulse once.

Vel Change vs Accel Change parameters

These two actually do the same thing which is adjust the velocity without taking the mass of the object into consideration. I can see why Epic named the boolean “Accel Change” on the Force functions even though it is a velocity adjustment because AddForce is intended to be called every frame over time so effectively it is an acceleration change. I think it would have been better to name both of the parameters “Ignore Mass” for consistency and clarity.

Radial

The radial functions provide an option to specify an origin where the force occurs such as the location where a bomb went off.

Angular

Angular is the spin on an object. So instead of adding force to x, y, z you are adding spin force to pitch, yaw, roll. I don’t think you meant to include this in your question as it doesn’t really relate to the other functions in question.

Launch Character

The LaunchCharacter function is not part of the physics simulation functions (no mass, no friction) like the others are and is only available on Characters instead of primitive components. This function adds or sets the character velocity to create basic force effects. Setting the xy and z override parameters will set the character velocity instead of adding to it.

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8

That was a great answer @Zectbumo54

Thanks for that!

9

Just wanna say thank you for this. Helped me get my project working :slight_smile:

10

Thanks for actually answering instead of asking the guy to RTFM…I’ve regularly had similar questions after reading their documentation.

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11

Lon
In no nhija

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12

Thank you! It’s actually nice when people answer the question instead of being edgy and crying “documentation”. Documentation fails at explaining half the stuff in there. We wouldn’t have answers.unreal or forums.unreal if documentation was THAT good.

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  1. AddForce

    Add force,unit:kg·cm/s^-2,should be called in a duration;
  2. AddImpulse

    Immediately give the object the speed of addforce in 1 second total;
  3. LaunchCharacter

    Just for character,may same as MovementComponent->SetVelocity?If you are on the ground, the speed will decrease rapidly,It’s about "braking deceleration "setting.
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14

Super cool and detailed answer. Please someone set this as the solution.