Raycast Hitting the backside of collider!

[proven bane]

I currently working on a FPS game where I have player who can shoot a gun via a raycast, The issue is that the raycast when it hits the player, it detects the collision on the backside of the collider while passing through the front side.

Does anyone have idea why it happens, or how to debug the same?

[modern drum]

Can you tell me how you know it's the backside?
Did you Debug the position?

[proven bane]

turns out that it wasnt backside, but rather that the hitpoint was further away

allow me to send some pictures for claritty

when I shoot the zombie and use the raycasthit to obtain the hitpoint and normal of the raycast. When the zombie is moving fast, the hitpoint seems to come behind the zombie
Allow me to show some picture to drive my explanation.
as we can see above, I drew a Gizmos Line from player's gun to the raycasthit.point and it comes to be behind the zombie
and this is when the zombie is at speed 10 (im using a navmesh agent)

exact same scenario but the speed of the zombie as been ramped up to 20

I want to add blood decal effects to where the player shot, but with raycast, I am not able to achive this functionality
Can anyone point out, what could be the potential issues?

[modern drum]

Welp, that's just the limit of physics calculations

The best approach would be to increase the size of the hitbox ig

[proven bane]

Damn, I really wanted to add decal to where the player shot. So do you have any idea how that can be done?

Will retracing the ray back and finding a point on the collider a good idea? Not that i know how to implement that 😆

[modern drum]

Actually, can you try Physics.SphereCast instead?
It might have a better chance to hit the collider correctly

[proven bane]

I can't increase the size of the collider cause, I plan to convert the 3D model into a ragdoll once the zombie is dead

[proven bane]

i will give it a try
thanks for the advice!

[proven bane]

i tried with spherecast

i drew a ray from player to raycasthit.point and drew a sphere a radius of the spherecast

the same issue still seems to persist

same scenario but the zombie's speed is made twice as fast

[modern drum]

I meant using SphereCast instead of RayCast, not Physics.OverlapSphere
SphereCast shoots a sphere instead of a ray, so it has a greater chance to collide properly.

[dusky wedge]

@proven bane have you tried calling Physics.SyncTransforms() before doing the cast? Im not saying you should do that in the actual game but it would be a way to varify where the problem is

[proven bane]

i have used Physics.SphereCast itself

[proven bane]

 if (Physics.SphereCast(PlayerEyes.position, 0.2f, Spray, out hitinfo,  1000, _enemy)) 
                {
                    GameManager.Instance.ShowBloodParticleEffect(hitinfo);
                    hitinfo.transform.gameObject.GetComponentInParent<HealthManager>().TakeDamage(CurrentGunData.Damage , PlayerEyes.forward,hitinfo.rigidbody); //damage the enemy if shot
                }

my code looks something like the above

[modern drum]

And it still overshoot?

[proven bane]

I am not familiar with this, i will try

[proven bane]

yep

im am completely confused as to why

[modern drum]

Is this in Update()?

[proven bane]

yes

[dusky wedge]

so did you try it already?

[proven bane]

there is a function i made called Shoot() that does the raycasting

[proven bane]

I DID!

and it FIXED THE PROBLEM!!!

THANK YOU SO MUCH @dusky wedge !!!
i was stuck on this for like 3 days 😆

[proven bane]

why do you advise i shouldnt use it in the real game?
is it expensive?

[dusky wedge]

yes it is expensive. now we atleast know its because it takes some time to the changes in navmeshagent position to update to the physics system

[proven bane]

ohhhhh

[dusky wedge]

btw do you have some animation on the zombie?

[proven bane]

this is my first time working on a 3D game, i used to make 2D games before

[proven bane]

yes
i play animation but i removed "Root Motion" so that it doesnt effect the navmesh traversal

once the zombie dies, i disable the animation component and activate forces on the ragdoll for the death

[dusky wedge]

you could try to change the Update Mode on the Animator to Update Physics. that alone could potentially fix the problem, though I'm bit sceptical

[proven bane]

let me give it a try

[proven bane]

ok small update

SyncTransforms actually doesnt really fix the problem, it just makes the hitpoint more accurate, but sometimes it goes off and into the enemy body

[proven bane]

I tried it, i dont see much of a difference 😢

[dusky wedge]

if that doesn't work, only better option (than Physics.SyncTransforms) that comes to my mind is to separate the Nav Mesh Agent and the visual zombie mesh with the colliders completely. the way I'd approach that would be to remove the Nav Mesh Agent component from the zombie, make a new empty gameobject with that Nav Mesh Agent component. now the zombie is not moved by the Nav Mesh Agent, the agent just moves by itself. to make the zomvie follow the agent again, you can set zombieRigidbodyWhatever.position = navMeshTransform.position (same for rotation). when you set rigidbodys position directly, it should immediately update to the physics system unlike navmesh does

[proven bane]

as of now i have the zombie model and its animation as the child of the navmesh object

[dusky wedge]

how deep in the enemy body does the hitpoint go? could it just be the colliders of the zombie representing the shape bit inaccurately?

[proven bane]

this happens when i put the update mode to Animate Physics

i mean the animation update mode

if the animation update mode is Normal, then its all perfect

[dusky wedge]

ah ok

[proven bane]

so basically this problem is arising cause the physics engine and the unity game loop are not in sync right

[dusky wedge]

then I guess the correct way would be to do this (so you don't need to call SyncTransforms) and keep the update mode to Normal

[proven bane]

I will give it a try!

[dusky wedge]

kinda... yeah. updating all the changes immediately to the physics engine would be bit too expensive I guess

[proven bane]

or would it be better if i put the shoot logic in fixed update

idk how that would effect the gameplay tho

[dusky wedge]

you could try but I'm afraid it won't still work. I think the changed transforms are not updated even every fixed update tho I'm not sure

[proven bane]

ohhhh

[proven bane]

Hey, i dont think this is possible, cause the animation is overriding the transforms

i tried doing what you did

[SerializeField] Rigidbody _enemyRoot;
    private void Update()
    {
        Debug.Log(transform.position);
        _enemyRoot.transform.localPosition = transform.localPosition;
        _enemyRoot.rotation = transform.rotation;
    }

i attached a script to the navmesh and did this

and the zombie is just stuck at where it is

but the navmesh is moving around

[dusky wedge]

does the zombie have a rigidbody on it?

[proven bane]

i trying to achieve ragdoll on it
so it has multiple rigidbodies on each of this limbs

[dusky wedge]

but does the main body have a rigidobdy?

[proven bane]

every red element you see on this image has a rigidbody

[proven bane]

noope

[proven bane]

Ok i added a rigidbod to the main body and tried

the problem persist

the raycast is still detecting inside the body

[dusky wedge]

now that you have rigidbody on the body, you should move the body using rb.position and rb.rotation, not the transform ones

[proven bane]

oh ok my bad

let me try again

IT WORKKSSSSSS

your solution fixed the problem

now im getting decals properly as to where the player shot

Thanks a lot @dusky wedge !

Thank you @modern drum as well!

[dusky wedge]

no problem, keep in mind that you have now added rigidbody to the main body. you may need to set that as kinematic when the ragdoll is enabled so it doesn't get messed up

[proven bane]

Yep sure!

thanks again

i guess now i will have to close this post

Untill we meet again!