Creating particles on a specific surface when a raycast passes through

[kindred sage]

Ey, just wanted to poke around in here. Had a question about raycasting and hitscans, couldn't find anything related to my question here or anywhere else online. Basically I wanted to know the best way to create decals/particles when a hitscan weapon for example, shoots through something like water, and hits the surface below it (like an ocean floor) but creates splash particles at the surface of the water.

I've tried using two separate raycasts in the same script that determine which surfaces are hit, the above water example using layer masks, but it's tricky. The raycast which hits the water instantiates a particle when I am looking at the water and firing the weapon, at even when looking at above-water terrain. Sorry for the long post, just hope there's a better solution out there of if I'm missing something, help could be provided

(I think this would also help with firing a weapon through glass for example)

[tough dove]

I'd still use 2 raycasts

One for the water (create splash)

and one from the hitPoint in the same direction

with different layer filtering

[kindred sage]

Seems like the best option, yeah

[tough dove]

I dont think you can do this in a single raycast

[kindred sage]

Ok

[tough dove]

2 raycasts gives you more control

and it is not less-performant

[kindred sage]

Then the only thing to work on would be to have it so the particle only displays on the surface of the water, not anywhere the player is looking when the water is within the raycast as well

[tough dove]

i don't get it

[kindred sage]

I know, it's kinda hard to explain

[tough dove]

just instantiate the particles on the hitPoint with the water

[kindred sage]

Well, the hitpoint needs to hit two surfaces, basically

[tough dove]

hitpoint cant hit anything

it's a point your ray hit

[kindred sage]

Like when you fire a bullet into a pool of water, the bullet hits the surface and creates a splash, but also hits the surface underneath the water

[tough dove]

yes so whats the problem

make 2 raycasts

[kindred sage]

Sorry, you're right

[tough dove]

RaycastHit waterHit;
RaycastHit surfaceBelowWaterHit;

if (Physics.Raycast(hitscanOrigin, hitscanDirection, out waterHit, maxDistance, waterLayerMask)) {
    Vector3 waterHitPoint = waterHit.point;
    InstantiateSplashParticles(waterHitPoint);

    if (Physics.Raycast(waterHitPoint + hitscanDirection * epsilon, hitscanDirection, out surfaceBelowWaterHit, maxDistance - epsilon, belowWaterLayerMask)) {
        Vector3 surfaceBelowWaterHitPoint = surfaceBelowWaterHit.point;
        InstantiateImpactParticles(surfaceBelowWaterHitPoint);
    }
}

want me to make you a step-by-step guide? 😄

[kindred sage]

Maybe lol

Ty tho, for responding so fast and all

[tough dove]

1. Fire raycast in the aiming direction with water layer mask

2. If you hit a object with a collider that has a water layer mask assigned, create splash particle at hit point. Inside the same if(where you hit the water), make another raycast in the same direction you were shooting but with under water layer mask

3. if you hit an object with a collider that has a under water layer mask, create impact particles at hitPoint

1 raycast for water

then if you hit water, second raycast from water position in the firing direction for ground

[kindred sage]

Yes, almost what I was doing, didn't think about casting a new raycast where the first one hits. That's interesting

[tough dove]

well you can do it from weapon's fire point aswell

but there's no point to do that really

i also assume you have some kind of firing range

so you cannot shoot at 1 kilometer with a pistol

so you can also set the raycast distance based on your firing range

let's say that you have pistol, with 10 range

distance from your gun to water hit point is 6 let's say

so the second raycast you make from water would be 4 distance (10-6)

sorry if that's to complicated 😄

[kindred sage]

No you're fine

I don't think that would be the most ideal, but it's definitely an option. You're saying that once a bullet hits the surface, it sends another raycast into the water. But I'm tryna think about if the weapon range would indeed complicate things a bit

Regardless if whether the range is 100km, maybe it's fine, as the raycast will hit the water surface anyway

[tough dove]

as i said

just manipulate the second raycasts ray distance

based on weapon shooting range

[kindred sage]

Tyvm yessir/ma'am