lime glen
Hi everyone. I am a new developer and I am trying to learn Unity. I recently coded my topdown character movement, moving him with rb.linearVelocity
I also have a PlayerManager script that check colliders when colliding and decrease health or kill him:
I want to add knockback when he collide with an Enemy. The only problem is that if the force is being applied every physic frame with fixedUpdate it wont work, unless i deactivate input, but is not what i want.
Any idea or help?
private Vector2 knockbackVelocity;
private float knockbackDuration;
private float knockbackTimer;
if (knockbackTimer > 0)
{
rb.linearVelocity = knockbackVelocity;
knockbackTimer -= Time.fixedDeltaTime;
}
dont consider those lines
clear wind
!code
clear wind
fickle ridge
else
{
// Sennò sta fermo
rb.linearVelocity = Vector2.zero;
}
there's your answer as to why it isn't working
lime glen
So, removing that makes my char sliding.
from sec 3 i am not even pressing any keybind
clear wind
you could add some linear drag or friction to dampen that, but that'd also reduce your speed
you could also disable the movement code for some duration of the knockback
lime glen
would you code movement in a different way? maybe i could rework the enire movement code but i dont know if that is better
clear wind
i have some variables for state, and while stunned i don't allow input movement
lime glen
private void OnCollisionEnter2D(Collision2D other)
{
if (other.gameObject.CompareTag("Enemy"))
{
TakeHit(other.gameObject.GetComponent<IDamager>().Damage);
if (health <= 0)
{
Die();
}
else
{
StartCoroutine(Knockback(other));
}
}
}
IEnumerator Knockback(Collision2D other)
{
Vector2 direction = transform.position - other.transform.position;
movement.isKnockback = true;
rb.AddForce(direction.normalized * knockback, ForceMode2D.Impulse);
yield return new WaitForSeconds(knockbackTime);
movement.isKnockback = false;
}
i "managed" to fix it by adding a Coroutine like this
acoustic arch
would you code movement in a different way? maybe i could rework the enire movem...
it depends what kind of game you are trying to make
lime glen
it is a topdown game
acoustic arch
it is a topdown game
you're making good progress and figuring out what does and doesn't make sense to model with physics
usually, for arcade style top down games, like Hotline Miami, physics is not used to drive the character
lime glen
so i would just move the char with transform?
clear wind
if you aren't using a rigidbody, sure
but rigidbodies definitely help a lot with making collision detection easy, so not sure why you'd opt out of that
lime glen
does colliders need rigidbodies?
clear wind
dynamic rigidbodies drive collision, colliders don't really do much if you don't have any rbs
unless you're using them for sweepcollider checks i suppose
acoustic arch
so i would just move the char with transform?
so because i haven't made that kind of game, i don't really know what to recommend. what i would do is look at this asset - https://topdown-engine.moremountains.com - and see what they did. you don't have to use the asset, but their thinking process was, "what is correct for the genre of game that people are trying to implement"
clear wind
unless you're using them for sweepcollider checks i suppose
hm, doesn't seem like 2d physics has that actually
acoustic arch
does colliders need rigidbodies?
in order to have collissions you do need rigidbodies
acoustic arch
so i would just move the char with transform?
let's talk about what is really going on
there's a feel for controls that players like in top down shooters. the controls were defined by console & arcade games (GTA 1) that predated physics frameworks + scene graph engines like unity.
none of these games were made with naturalistic physics engines like the one in Unity. sometimes people call these games arcade physics games.
in Unity, it's really convenient to express your game rules, like not being able to move into walls and jumping or whatever, with naturalistic physics
the hard part of making this is you want to be able to define walls using 3d colliders, but you want movement that works like gta 1
when you try to use the physics forces to recreate GTA 1 character movement, things don't work well. all the emergent behavior of using the physics engine for movement doesn't occur in GTA 1. GTA 1 they don't have a naturalistic physics engine
@lime glen does this make sense?
lime glen
Yeah, so using only transform would make me going inside colliders maybe?
acoustic arch
that's what the more mountains top down asset does. they carefully set everything up so that you can define walls using 3d colliders, but the movement feels like GTA 1
acoustic arch
Yeah, so using only transform would make me going inside colliders maybe?
yeah exactly
acoustic arch
Yeah, so using only transform would make me going inside colliders maybe?
this is such a complex issue that unity actually acquired the asset (hired the developer of) and made an official package out of Rival (https://discussions.unity.com/t/experimental-character-controller-package-now-available-formerly-known-as-rival/911268)
lime glen
is there a way i can look at moremountains games code so that i can learn from those?
acoustic arch
like i can go and download the top down engine for you and say how they did things, i'm pretty sure they compute the momentum every frame at "the right time", then they check if any collissions occurred after the physics simulation, and then they reconcile the physics consequences with the user input consequences to calculate a new momentum.
acoustic arch
is there a way i can look at moremountains games code so that i can learn from t...
you mean without buying it? no. you'd have to buy it. but i think it's the right idea
almost all of the solutions involve treating the physics and player inputs in phases
the important thing is you are trying all these things and figuring it out
lime glen
mhh. Since i still am new i wont spend money. But maybe i can work around decompiling already top down existing games?
acoustic arch
mhh. Since i still am new i wont spend money. But maybe i can work around decomp...
hmm that will be a huge distraction lol
acoustic arch
the people i know who are best at this already "see" games like GTA1 on a frame by frame basis, and then they sort of intuitively write code that looks like
inside the execution orderl loop
gather the user's input so far
apply the physics forces to model the input
allow physics to execute
look at what happened according to physics. if i am colliding agains ta wall, for example, use that.
reconcile player inputs and update transforms.
acoustic arch
or some itch.io simple games to see how they handle that
they don't
i mean this is why GTA makes a bajillion dollars lol
lime glen
i didnt thought it was that hard to just handle a character moving and apply forces while moving lol
acoustic arch
yeah it turns out ot be ridiculously hard in Unity
like why use unity if you aren't going to use Physics
another POV is, this is why people say they like making these retro feeling games in other engines, but then, because they're using something with product development measured in the hundreds of thousands of dollars instead of billions, they never ship a game
lime glen
yeah, then i should use gamemaker or something like that if I want to move stuff without physics
ideally
acoustic arch
the reason you want to use unity is so that you can attach a collider to an object, and now your character can't move into it
versus say gamemaker, where you can only not move into things that are tiles that are impassable
big difference
lime glen
yeah
acoustic arch
it's all these emergent behaviors
you can look at Rival (unity dots character controller)
lime glen
i guess i'll try to find a way to handle multiple physics at the same time
acoustic arch
actually you could very well just use it as your top down game character controller and learn a LOT
lime glen
i will look at that now i guess
lime glen
is it for a 2D game?
acoustic arch
the way this character controller works, if you model your game on the xz plane, it will feel right
so just from reading these docs, i've learned that the ECS framework (you should think of ECS as Unity 2.0) is flexible enough taht you can implement your own kind of physics object. so imagine if rigidbody had an abstract base class called PhysicsObject, this implements physicsobject.
clear wind
charactercontroller is decidedly for 3d
acoustic arch
whereas the way to achieve that in unity with kinematic rigidbodies is a lot more cantanerkous. it's not at all impossible. that's what the moremountains asset does
lime glen
i guess i'll try to find a way to handle multiple physics at the same time
maybe if i could add forces together and after a period of time silde back to the movement velocity
moving = velocity
knockback = moving.velocity + knockback
after a time
slide to moving.velocity
i know that this is only for this case and not for everything but i could work around like with a function that
takes a force as argument
add that to another rb.velocity
after a time (in the argument)
slide back to rb.velocity