Bullet Penetration Method

[earnest tendon]

The variables that are accessible are the RaycastResult, The Direction and Origin of the Raycast (Vector3 obviously), The Instance properties and what im trying to get from this is the other surface end point in a Vector3 value (Penetration length can be obtained by subtracting origin Vector3, the calculated Vector3 Penetration point and index .Magnitude), I have tried doing the method where you perform a 2nd Raycast check with the 1st RaycastResult Instance excluded and then the 3rd Raycast is from the 2nd RaycastResult Position with the inverted direction and get the 3rd RaycastResult Position and subtract the 1st and 3rd Position and get the Penetration length, this leads to more bugs one of which that if an object is inside the part it will get inaccurate results.

Maybe is there a bunch of math formulas that can help only to calculate the Penetration position and its length ?

Here is the method I tried came up with

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()
local runService = game:GetService("RunService")

local function raycastAndPenetrate()
    local direction = mouse.UnitRay.Direction * 1000
    local currentOrigin = mouse.Origin.Position

    while runService.RenderStepped:Wait() do
        local params = RaycastParams.new()
        local firstHitResult = workspace:Raycast(currentOrigin, direction, params)
        if firstHitResult then
            if direction.Magnitude - (firstHitResult.Position - currentOrigin).Magnitude <= 0 then
                return firstHitResult
            else
                params.FilterType = Enum.RaycastFilterType.Exclude
                params:AddToFilter(firstHitResult.Instance)
                local secondHitResult = workspace:Raycast(firstHitResult.Position, direction, params)
                if secondHitResult then
                    local backDirection = (firstHitResult.Position - secondHitResult.Position).Unit * direction.Magnitude
                    params.FilterType = Enum.RaycastFilterType.Include
                    local backHitResult = workspace:Raycast(secondHitResult.Position, backDirection, params)
                    if backHitResult and backHitResult.Instance == firstHitResult.Instance then
                        local penetrationDepth = (firstHitResult.Position - backHitResult.Position).Magnitude
                        if penetrationDepth > 5 then -- getMaxPenDepth(penetrationDepth, firstHitResult.Material)
                            return firstHitResult
                        else
                            currentOrigin = backHitResult.Position
                        end
                    else
                        return firstHitResult
                    end
                else
                    return firstHitResult
                end
            end
        else
            return
        end

    end
end

mouse.Button1Down:Connect(raycastAndPenetrate)```

[earnest tendon]

[twilit fractal]

why is it so long

All you need to do is check if hit part is penetrable, if yes, raycast again from result position to goal and add the part into a blacklist

Oh I see you're trying to get the depth that needs to be shot through

[earnest tendon]

No I already know that, my goal is to get both penetration depth and the position, not using more raycast but math

also since its penetration the first RaycastResult value is accessible for the penetration calculation (and the Origin and Direction)

[grand goblet]

Sounds interesting

You could look into RaycastResult.Normal

As far as I know, there is no way to work with part surfaces directly

Using the part size may be inconsistent with non blocks like spheres

A double raycast sounds like the best choice

You can filter it to only include the part that’s being checked for penetration

But I don’t know any way to check mathematically

[earnest tendon]

Dang forgot about that

guess ill find out when I finish highschool

[grand goblet]

I don’t think it’s actually possible with just math

I had a similar issue with something else a while ago

Actually it’s a very similar issue 🤔

I was trying to do it without raycasting but in the end, I decided it wasn’t worth the trouble

If you are curious: https://discord.com/channels/448986884497211392/1275985899825659935

[twilit fractal]

You are trying to get the depth of which the bullet has to travel through without raycast?

[earnest tendon]

yeah the other end

[twilit fractal]

Hmm, I dont think there is a way without assuming its a square

Actually even for a square you would still need more and sifferent data

Since you dont actually know much about the hit part

[still prairie]

@earnest tendon

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()
local runService = game:GetService("RunService")

local function performRaycast(origin, direction, filterInstance)
    local params = RaycastParams.new()
    if filterInstance then
        params.FilterDescendantsInstances = { filterInstance }
        params.FilterType = Enum.RaycastFilterType.Exclude
    end
    return workspace:Raycast(origin, direction, params)
end

local function calculatePenetration(firstHit, direction)
    local penetrationDir = direction.Unit * 1000
    local secondHit = performRaycast(firstHit.Position, penetrationDir, firstHit.Instance)
    
    if secondHit then
        local reverseDir = (firstHit.Position - secondHit.Position).Unit * direction.Magnitude
        local backHit = performRaycast(secondHit.Position, reverseDir)
        
        if backHit and backHit.Instance == firstHit.Instance then
            local penetrationDepth = (firstHit.Position - backHit.Position).Magnitude
            return penetrationDepth, backHit.Position
        end
    end
    return 0, firstHit.Position
end

local function raycastAndPenetrate()
    while runService.RenderStepped:Wait() do
        local direction = mouse.UnitRay.Direction * 1000
        local origin = mouse.Origin.Position
        local hitResult = performRaycast(origin, direction)
        
        if hitResult then
            local penetrationDepth, penetrationPoint = calculatePenetration(hitResult, direction)
            if penetrationDepth > 5 then
                return penetrationPoint
            else
                return hitResult.Position
            end
        else
            return
        end
    end
end

mouse.Button1Down:Connect(raycastAndPenetrate)

[earnest tendon]

There is the first RaycastResult

[earnest tendon]

Looks like you gave me the same method I want to avoid and gave me no explanation

[still prairie]

give me what you want, give me your desired result to the tee, help me understand.

i can also toss some comments for you.

[maiden onyx]

** You are now Level 3! **

[earnest tendon]

maybe put the post description to ur model

[earnest tendon]

this one

[twilit fractal]

Yeah that's where it ends

Hit position, size of the part is irrelevant because even if you knew how to get around it being oriented differently

if its hit at an angle it no longer applies

Normal wouldnt help at all either

So all you really know is the hit position and bullet direction

I don't think you can find much from this without another ray cast

I am still not sure where your third raycast comes in though

[earnest tendon]

yea like this, theres gotta be mathematical wizardry to make this happen

[twilit fractal]

I highly doubt it

Only additional information you can get is length from entry point to corner

[earnest tendon]

btw what were you explaining

[twilit fractal]

?

[earnest tendon]

ee

[twilit fractal]

Which means you could get rid of one side, but you would need to subtract it from exit point distance to edge

which you cant without knowing it

[earnest tendon]

the method to get the exit point from the entry point

I know how to get the depth/length if you didnt know

[twilit fractal]

Well it's not a method because it isn't possible imo

[twilit fractal]

How?

[earnest tendon]

(thing2.Position - thing1.Position).Magnitude

[twilit fractal]

Oh well yeah

[earnest tendon]

both thing's are the entry/exit points

[twilit fractal]

But our issue is getting thing

[earnest tendon]

no

because

[twilit fractal]

All you know is entry

[earnest tendon]

The first RaycastResult

[twilit fractal]

without a second raycast

Yeah

That only gives us entry

[earnest tendon]

yes

[twilit fractal]

We can't do much with that

[earnest tendon]

Yeah but a Raycast result gives us the instance (the thing) and the point

[twilit fractal]

Yeah but you don't know which side is which

You don't even know which side you hit

You only know the normal of that face

There is no way, especially in any shape other than rectangle or square

But I'm a bit confused on where you use backhit and fronthit raycasts

[earnest tendon]

First raycast gets the first instance we want to penet, 2nd raycast excluded the instance and get a stopping point to raycast back, third raycast, goes reverse direction

so just subtracting the 1st raycast hit point and the 3rd one gets the penetration depth

is there a game that documents their game

which also happens to be a shooter

[twilit fractal]

There probably is

I don't know any though

[twilit fractal]

Could you draw this out

[earnest tendon]

any questions

this is the method I came up with,

and theres no offsets between every raycast origin

same direction

2nd raycast Origin is from where the 1st raycast hit

3rd origin is from 2nd hit

but direction is inverted

[twilit fractal]

what if there is no second object

[earnest tendon]

probably I think it went off the sky

and returned the 1st raycast result

so yeh

[twilit fractal]

You are saving a raycast but this isn't much faster

[earnest tendon]

its innacurate

[twilit fractal]

It's slower in some instances too

Raycast length matters

It would be better just using the more obvious solution

[earnest tendon]

it doesnt have to hit anything if the 2nd fails

[twilit fractal]

Yeah but the length

The length of the second one

It needs to check far more

[earnest tendon]

oh Ill just override it with like

1024 studs

2048

[twilit fractal]

Thats still a lot more then just adding another raycast

thats going to be like 5 studs

[earnest tendon]

yeah but the purpose of the 2nd ray is to find a candidate for the 3rd raycast origin

[maiden onyx]

** You are now Level 4! **

[earnest tendon]

far from the instance we want to penetrate

im bad english

[twilit fractal]

Yeah youre trying to skip one

[earnest tendon]

skip what?

[twilit fractal]

Here you have three raycasts

two of them can have varying lengths

depending on how far an object is

and one is max penetration length long

compared to the other solution

which has three x long raycasts

So if the second object is a 100 studs away

thats 95 more studs to check

Making a raycast isn't expensive

How much it checks is the important part

[twilit fractal]

(assuming max depth is 5 studs)

Your solution saves a miniscule amount of ram at the cost of speed

which is far more important when you have a shooter game

[earnest tendon]

How do phantom forces

nvm

[twilit fractal]

I dont think thats public

[earnest tendon]

source code were leaked maybe I could learn

but

[twilit fractal]

Were talking below kilobyte of memory

[earnest tendon]

what if theres a part inside in the penet part, and the 2nd raycast takes it

[twilit fractal]

Good thinking

Easy fix though, just check

[earnest tendon]

I knew how to get the length from the 1st point and the 2nd one

how do I know its not inside

that kinda goes back to the mathematical method I wanted to find out

[twilit fractal]

Well that matters on how raycasts handle being inside of a part

[earnest tendon]

sorry brain

[twilit fractal]

which I don't actually know

If it ignores then we might have a slight issue

if it hits, then itll hit the exact same spot as entrance

meaning it exceeded max limit so dont penetrate

simplest solution is to not overcomplicate the system

and not worry about length at all

which is what phantom forces likely does

[earnest tendon]

ok imma look inside their 2016 save

[twilit fractal]

because no one will care or notice that since they hit is at a different angle they do 2% less damage

[earnest tendon]

im stupid asf 💔

[still prairie]

ReplicatedStorage/Config/Combat.lua

--!strict
-- Centralized, tunable values (no magic numbers in logic)

export type MaterialResistanceMap = {[Enum.Material]: number}

local Combat = {
    -- Shooting
    RateLimitSeconds = 0.06,
    MaxRange = 1000.0,
    BaseEnergy = 25.0,
    MaxPenetrations = 16,
    MinDirMagnitude = 1e-4,

    -- Damage
    HitDamage = 20.0,

    -- Penetration
    Epsilon = 1e-3,
    DefaultMaterialResistance = 2.0,
    PenMultiplierAttribute = "PenetrationMultiplier" :: string,
    MaterialResistance = {
        [Enum.Material.Air] = 0.0,
        [Enum.Material.Plastic] = 0.8,
        [Enum.Material.Wood] = 1.0,
        [Enum.Material.Glass] = 0.5,
        [Enum.Material.Concrete] = 3.0,
        [Enum.Material.Brick] = 2.2,
        [Enum.Material.Metal] = 5.0,
        [Enum.Material.DiamondPlate] = 6.0,
        [Enum.Material.Granite] = 4.0,
        [Enum.Material.Slate] = 3.5,
        [Enum.Material.Asphalt] = 2.6,
        [Enum.Material.Grass] = 0.3,
        [Enum.Material.Ice] = 0.6,
    } :: MaterialResistanceMap,

    -- Anti-exploit
    MaxOriginOffsetFromCharacter = 15.0, -- studs from HumanoidRootPart
}

return Combat

ReplicatedStorage/Modules/Penetration.lua

ServerScriptService/ServerShoot.server.lua