How can I sync up the server and clients bullets so that they are in the same position? I want to make a bow and arrow and having the arrow hit a player on one screen but completely miss on another is bad. I tried using my own physics equations but its been pretty wacky and I noticed on line 146 of the fastcast module there seems to be built in support for delta time, is there a way I can use this?
You can’t Sync server and client bullets 100% due to latency.
The best way you could sync it is fire the arrow client sided and replicate the arrow for all other clients client sided aswell.
And do the Damage on the server with Sanity checks
I have a question. I had this very weird bug now where the weapon just randomly stops working after death. Some weapons work, some don’t. There is no error in the output or console and I don’t know why.
Any1 had a similar problem?
You can sync them to nearly 100% accuracy.
When you shoot on client, the server can offset the bullet based on your ping. I did this by manipulating some of the variables when fast cast starts. The issue with this is, close range shots will go through walls, but to fix that I added a raycast and its functioning fine now, although my syntax is pretty crappy.
Theres a bug with this module that when you add gravity, the bullets have a slight chance to go through the ground.
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For the sake of simplicity I’m only using one caster on the server and one on the client for all projectiles, server is for damage and replicating to other clients, and client is for rendering your own projectiles instantly (before remote firing the server) and rendering projectiles sent by the server
ProjectileReplication_Client Module
local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local TweenService = game:GetService("TweenService")
local Quire = require(ReplicatedStorage:WaitForChild("Shared").Quire)
local NetworkUtil = Quire("NetworkUtil")
local Caster = Quire("FastCast").new()
local Repr = Quire("Repr")
local projectileReplicationEvent = NetworkUtil:GetRemoteEvent("ProjectileReplicationEvent")
local projectileFolder = ReplicatedStorage:WaitForChild("Projectiles")
local workspaceProjectiles = workspace:WaitForChild("Projectiles")
-- black list setup and updating
local blacklist = {workspaceProjectiles}
local function onPlayerAdded(player)
local function onCharacterAdded(character)
table.insert(blacklist, character)
character.AncestryChanged:Connect(function(_, parent)
if parent then return end
table.remove(blacklist, table.find(blacklist, character))
end)
end
if player.Character then onCharacterAdded(player.Character) end
player.CharacterAdded:Connect(onCharacterAdded)
end
for _, player in ipairs(Players:GetPlayers()) do
onPlayerAdded(player)
end
Players.PlayerAdded:Connect(onPlayerAdded)
-- Projectiles
-- fireball
local fireBallProjectile = projectileFolder.FireballPart
local fireBallTweenTime = .2
local fireBallFadeTweenInfo = TweenInfo.new(fireBallTweenTime)
local fireBallTweenProperties = {Transparency = 1}
local ProjectileReplication_Client = {}
function ProjectileReplication_Client.fireProjectile(projectileData, origin, direction, velocity, _, _, ignoreWater, bulletAcceleration, canPierceFunction)
if projectileData.projectileType == "Fireball" then
local projectileCosmeticPart = fireBallProjectile:Clone()
projectileCosmeticPart.Parent = workspaceProjectiles
projectileData.fireBallFadeTween = TweenService:Create(projectileCosmeticPart, fireBallFadeTweenInfo, fireBallTweenProperties)
Caster:FireWithBlacklist(
projectileData,
origin,
direction,
velocity,
blacklist,
projectileCosmeticPart,
ignoreWater,
bulletAcceleration,
canPierceFunction
)
end
end
Caster.RayHit:Connect(function(projectileData, hitPart, hitPoint, normal, material, projectile)
if projectileData.projectileType == "Fireball" then
projectileData.fireBallFadeTween:Play()
wait(fireBallTweenTime)
end
projectile:Destroy()
end)
Caster.LengthChanged:Connect(function(projectileData, castOrigin, segmentOrigin, segmentDirection, length, projectile)
local baseCF = CFrame.new(segmentOrigin, segmentOrigin + segmentDirection)
local projectHalfSize = projectile.Size.Z/2
projectile.CFrame = baseCF * CFrame.new(0, 0, -(length - projectHalfSize))
end)
projectileReplicationEvent.OnClientEvent:Connect(ProjectileReplication_Client.fireProjectile)
return ProjectileReplication_Client
ProjectileReplication_Server Module
local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Quire = require(ReplicatedStorage:WaitForChild("Shared").Quire)
local NetworkUtil = Quire("NetworkUtil")
local Caster = Quire("FastCast").new()
local projectileReplicationEvent = NetworkUtil:GetRemoteEvent("ProjectileReplicationEvent")
local workspaceProjectiles = workspace:WaitForChild("Projectiles")
-- black list setup and updating
local blacklist = {workspaceProjectiles}
local function onPlayerAdded(player)
local function onCharacterAdded(character)
table.insert(blacklist, character)
character.AncestryChanged:Connect(function(_, parent)
if parent then return end
table.remove(blacklist, table.find(blacklist, character))
end)
end
if player.Character then onCharacterAdded(player.Character) end
player.CharacterAdded:Connect(onCharacterAdded)
end
for _, player in ipairs(Players:GetPlayers()) do
onPlayerAdded(player)
end
Players.PlayerAdded:Connect(onPlayerAdded)
local ProjectileReplication_Server = {}
function ProjectileReplication_Server.fireProjectile(projectileData, origin, direction, velocity, _, projectileCosmeticPart, ignoreWater, bulletAcceleration, canPierceFunction)
Caster:FireWithBlacklist(
projectileData,
origin,
direction,
velocity,
blacklist,
projectileCosmeticPart,
ignoreWater,
bulletAcceleration,
canPierceFunction
)
for _, player in ipairs(Players:GetChildren()) do
if projectileData.player ~= player then
projectileReplicationEvent:FireClient(
player,
projectileData,
origin,
direction,
velocity,
projectileCosmeticPart,
nil,
ignoreWater,
bulletAcceleration,
canPierceFunction
)
end
end
end
Caster.RayHit:Connect(function(projectileData, hitPart, hitPoint, normal, material, projectile)
local humanoid = hitPart and hitPart.Parent:FindFirstChild("Humanoid")
if humanoid then
humanoid:TakeDamage(projectileData.damage)
end
end)
return ProjectileReplication_Server
Fireball_Client Tool Script
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Players = game:GetService("Players")
local Quire = _G.Quire
local ProjectileReplication_Client = Quire("ProjectileReplication_Client")
local ProjectileReplication = Quire("ProjectileReplication")
local tool = script.Parent
local handle = tool:WaitForChild("Handle")
local player = game.Players.LocalPlayer
local mouse = player:GetMouse()
local character
local rightHand
local remotesFolder = tool.Remotes
local shootEvent = remotesFolder.ShootEvent
local statsFolder = tool.Stats
local stateFolder = tool.State
local SPEED = statsFolder.Speed.Value
local RANGE = statsFolder.Range.Value
local DAMAGE = statsFolder.Damage.Value
local PROJECTILE_TYPE = statsFolder.ProjectileType.Value
local FIREBALL_OFFSET = statsFolder.FireballOffset.Value
local GRAVITY = statsFolder.Gravity.Value
local COOLDOWN_TIME = statsFolder.CooldownTime.Value
local COOLDOWN_LOOP_WAIT = COOLDOWN_TIME * 1.2 -- leeway for network delay
local stateFolder = tool.State
local lastActivationTick = tick()
local looping = false
local function shoot()
local now = tick()
if now - lastActivationTick < COOLDOWN_TIME then return end
lastActivationTick = now
local origin = handle.Position + FIREBALL_OFFSET
local mouseDirection = (mouse.Hit.Position - origin).Unit
local direction = mouseDirection * RANGE
local velocity = mouseDirection * SPEED
local projectileCosmeticPart = nil
local ignoreWater = true
local bulletAcceleration = GRAVITY
local canPierceFunction = function(hitPart, hitPoint, normal, material)
return false
end
local projectileData = {
projectileType = PROJECTILE_TYPE,
player = player,
character = character,
}
ProjectileReplication_Client.fireProjectile(
projectileData,
origin,
direction,
velocity,
nil,
projectileCosmeticPart,
ignoreWater,
bulletAcceleration,
canPierceFunction
)
shootEvent:FireServer(mouseDirection)
end
local function shootLoop()
if looping then return end
looping = true
while looping do
shoot()
wait(COOLDOWN_LOOP_WAIT)
end
end
tool.Equipped:Connect(function()
character = tool.Parent
rightHand = character:WaitForChild("RightHand")
mouse.TargetFilter = character
end)
tool.Unequipped:Connect(function()
looping = false
end)
tool.Activated:Connect(shootLoop)
tool.Deactivated:Connect(function()
looping = false
end)
Fireball_Server Tool Script
local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local TweenService = game:GetService("TweenService")
local Quire = _G.Quire
local NetworkUtil = Quire("NetworkUtil")
local ProjectileReplication_Server = Quire("ProjectileReplication_Server")
local projectileReplicationEvent = NetworkUtil:GetRemoteEvent("ProjectileReplicationEvent")
local tool = script.Parent
local handle = tool:WaitForChild("Handle")
local player = Players:FindFirstChild(tool.Parent.Name) or tool:FindFirstAncestorOfClass("Player")
local character = player.Character
local rightHand = character.RightHand
local remotesFolder = tool.Remotes
local shootEvent = remotesFolder.ShootEvent
local statsFolder = tool.Stats
local SPEED = statsFolder.Speed.Value
local RANGE = statsFolder.Range.Value
local DAMAGE = statsFolder.Damage.Value
local PROJECTILE_TYPE = statsFolder.ProjectileType.Value
local FIREBALL_OFFSET = statsFolder.FireballOffset.Value
local GRAVITY = statsFolder.Gravity.Value
local COOLDOWN_TIME = statsFolder.CooldownTime.Value
local stateFolder = tool.State
local lastActivationTick = tick()
local function shoot(mouseDirection)
local now = tick()
if now - lastActivationTick < COOLDOWN_TIME then return end
lastActivationTick = now
local origin = handle.Position + FIREBALL_OFFSET
local direction = mouseDirection * RANGE
local velocity = mouseDirection * SPEED
local projectileCosmeticPart = nil
local ignoreWater = true
local bulletAcceleration = GRAVITY
local canPierceFunction = function(hitPart, hitPoint, normal, material)
return false
end
local projectileData = {
projectileType = PROJECTILE_TYPE,
damage = DAMAGE,
player = player,
character = character,
}
ProjectileReplication_Server.fireProjectile(
projectileData,
origin,
direction,
velocity,
nil,
projectileCosmeticPart,
ignoreWater,
bulletAcceleration,
canPierceFunction
)
end
shootEvent.OnServerEvent:Connect(function(plr, direction)
if plr == player and assert(direction.Magnitude <= 1.1, "invalid direction") then
shoot(direction)
end
end)
It works, but is there any drawbacks when using only one caster for every projectile?, and I’m also having to pass an additional parameter (projectileData) to fast cast and passing it back through the events (RayHit, etc)
I haven’t had any performance issues yet, but I don’t have access to a large amount of testers to see if there will be
2 Likes
I have already answered this question – see Reply #148
@4slug I’ll investigate this. I did notice that once during my own tests but I couldn’t get it to happen again after that.
@Quoteory While this is an option, I addressed this when talking to ChefJustice in Reply #161 – The basic idea is that while you can do this setup, it’s only good if you are comfortable with handling that data. There’s no performance differences from using a single caster vs. casters for each and every individual player. The only thing that should determine your plan of action is your personal preference: if you find it easier to use a singleton caster and manually track who’s doing what, then by all means continue doing this, alternatively, if you find it easier to have individual objects for individual people, this is just fine as well.
The only problems come up from creating a new caster each time the gun is fired, since as mentioned in the past and in the module itself, a caster should represent an entire gun. It’s analogous to the firing mechanism of a gun, in a crude sense. Each gun has its own design.
3 Likes
I added a issue request on the github that explains it in a little more detail as well as a gif
Exploiters can see data sent from the client to the server via remotes without actually looking at any script source code and since fastcast is open source I don’t think an exploiter would have to look too far to find out how it works lol. Anyways if you’re going to be handling hit detection on the client then you should at least do some server verification
Ah yeah on that side of things it would be weak. My main point there was things like bullet manipulation – it’s virtually impossible for them to reliably (assuming they can at all) edit that information during runtime, compared to something like a part based bullet which can be trivially edited.
There is an issue, with a module. After time of massive shooting using this module. The firing slows down significantly because of overload. I dont know exactly what is causing this to happen.
Everything works reliably, but i literally do not know how to add gravity to the bullets with the new version
how do i add gravity to the bullets
1 Like
bulletAcceleration argument in the :Fire function
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Hey 
sorry for bumping this thread
But I just wanted to ask
Is there any example available of FastCast for First Person View (FPS)?
Glad you asked, haha 
I’m working on a framework which I believe will fit your desire. Hope you like it Awesome_Playz123 fps test v1 - Roblox
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It looks really awesome
I was also messing around with it lol
And did this
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You scared me, lol. I thought you took my game? What a relief 
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No no I meant like messing around with the module lol
Btw will you be going to make your framework opensource?
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Probably not. I’m going to try and make a game out of it. My discord username is lucid#9360 just in case you need help with anything and also I made an open source fastcast test Untitled FastCast Voting Game Simulator 2020 - Roblox for you to study off 
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Good Luck
Thanks for the help
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