Custom FireBullets

gs = {
    random = include("minstd.lua") -- from https://github.com/Kefta/Lua-MINSTD
}


DEBUG_LENGTH = 3

COORD_EXTENT = 2 * 16384
// Maximum traceable distance (assumes cubic world and trace from one corner to opposite)
// COORD_EXTENT * sqrt(3)
MAX_TRACE_LENGTH = math.sqrt(3) * COORD_EXTENT

SF_BREAK_NO_BULLET_PENETRATION = 0x0800

-- From the math lib
do
    local band = bit.band
    local bnot = bit.bnot
    local bor = bit.bor
    local bxor = bit.bxor
    local rshift = bit.rshift
    local floor = math.floor
    local log = math.log
    local sin = math.sin
    local cos = math.cos
    local rad = math.rad
    local abs = math.abs
    local exp = math.exp

    // The four core functions - F1 is optimized somewhat
    // local function f1(x, y, z) bit.bor(bit.band(x, y), bit.band(bit.bnot(x), z)) end
    // This is the central step in the MD5 algorithm.
    local function Step1(w, x, y, z, flData, iStep)
        w = w + bxor(z, band(x, bxor(y, z))) + flData

        return bor((w * 2^iStep) % 0x100000000, floor(w % 0x100000000 / 2^(0x20 - iStep))) + x
    end

    local function Step2(w, x, y, z, flData, iStep)
        w = w + bxor(y, band(z, bxor(x, y))) + flData

        return bor((w * 2^iStep) % 0x100000000, floor(w % 0x100000000 / 2^(0x20 - iStep))) + x
    end

    local function Step3(w, x, y, z, flData, iStep)
        w = w + bxor(bxor(x, y), z) + flData

        return bor((w * 2^iStep) % 0x100000000, floor(w % 0x100000000 / 2^(0x20 - iStep))) + x
    end

    local function Step4(w, x, y, z, flData, iStep)
        w = w + bxor(y, bor(x, bnot(z))) + flData

        return bor((w * 2^iStep) % 0x100000000, floor(w % 0x100000000 / 2^(0x20 - iStep))) + x
    end

    function math.MD5Random(iSeed)
        --gs.CheckType(iSeed, 1, TYPE_NUMBER)

        -- FIXME: https://github.com/Facepunch/garrysmod-issues/issues/2820
        local bEnabled = jit.status()

        if (bEnabled) then
            jit.off()
        end

        iSeed = iSeed % 0x100000000

        local a = Step1(0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, iSeed + 0xd76aa478, 7)
        local d = Step1(0x10325476, a, 0xefcdab89, 0x98badcfe, 0xe8c7b7d6, 12)
        local c = Step1(0x98badcfe, d, a, 0xefcdab89, 0x242070db, 17)
        local b = Step1(0xefcdab89, c, d, a, 0xc1bdceee, 22)
        a = Step1(a, b, c, d, 0xf57c0faf, 7)
        d = Step1(d, a, b, c, 0x4787c62a, 12)
        c = Step1(c, d, a, b, 0xa8304613, 17)
        b = Step1(b, c, d, a, 0xfd469501, 22)
        a = Step1(a, b, c, d, 0x698098d8, 7)
        d = Step1(d, a, b, c, 0x8b44f7af, 12)
        c = Step1(c, d, a, b, 0xffff5bb1, 17)
        b = Step1(b, c, d, a, 0x895cd7be, 22)
        a = Step1(a, b, c, d, 0x6b901122, 7)
        d = Step1(d, a, b, c, 0xfd987193, 12)
        c = Step1(c, d, a, b, 0xa67943ae, 17)
        b = Step1(b, c, d, a, 0x49b40821, 22)

        a = Step2(a, b, c, d, 0xf61e25e2, 5)
        d = Step2(d, a, b, c, 0xc040b340, 9)
        c = Step2(c, d, a, b, 0x265e5a51, 14)
        b = Step2(b, c, d, a, iSeed + 0xe9b6c7aa, 20)
        a = Step2(a, b, c, d, 0xd62f105d, 5)
        d = Step2(d, a, b, c, 0x02441453, 9)
        c = Step2(c, d, a, b, 0xd8a1e681, 14)
        b = Step2(b, c, d, a, 0xe7d3fbc8, 20)
        a = Step2(a, b, c, d, 0x21e1cde6, 5)
        d = Step2(d, a, b, c, 0xc33707f6, 9)
        c = Step2(c, d, a, b, 0xf4d50d87, 14)
        b = Step2(b, c, d, a, 0x455a14ed, 20)
        a = Step2(a, b, c, d, 0xa9e3e905, 5)
        d = Step2(d, a, b, c, 0xfcefa3f8, 9)
        c = Step2(c, d, a, b, 0x676f02d9, 14)
        b = Step2(b, c, d, a, 0x8d2a4c8a, 20)

        a = Step3(a, b, c, d, 0xfffa3942, 4)
        d = Step3(d, a, b, c, 0x8771f681, 11)
        c = Step3(c, d, a, b, 0x6d9d6122, 16)
        b = Step3(b, c, d, a, 0xfde5382c, 23)
        a = Step3(a, b, c, d, 0xa4beeac4, 4)
        d = Step3(d, a, b, c, 0x4bdecfa9, 11)
        c = Step3(c, d, a, b, 0xf6bb4b60, 16)
        b = Step3(b, c, d, a, 0xbebfbc70, 23)
        a = Step3(a, b, c, d, 0x289b7ec6, 4)
        d = Step3(d, a, b, c, iSeed + 0xeaa127fa, 11)
        c = Step3(c, d, a, b, 0xd4ef3085, 16)
        b = Step3(b, c, d, a, 0x04881d05, 23)
        a = Step3(a, b, c, d, 0xd9d4d039, 4)
        d = Step3(d, a, b, c, 0xe6db99e5, 11)
        c = Step3(c, d, a, b, 0x1fa27cf8, 16)
        b = Step3(b, c, d, a, 0xc4ac5665, 23)

        a = Step4(a, b, c, d, iSeed + 0xf4292244, 6)
        d = Step4(d, a, b, c, 0x432aff97, 10)
        c = Step4(c, d, a, b, 0xab9423c7, 15)
        b = Step4(b, c, d, a, 0xfc93a039, 21)
        a = Step4(a, b, c, d, 0x655b59c3, 6)
        d = Step4(d, a, b, c, 0x8f0ccc92, 10)
        c = Step4(c, d, a, b, 0xffeff47d, 15)
        b = Step4(b, c, d, a, 0x85845e51, 21)
        a = Step4(a, b, c, d, 0x6fa87e4f, 6)
        d = Step4(d, a, b, c, 0xfe2ce6e0, 10)
        c = Step4(c, d, a, b, 0xa3014314, 15)
        b = Step4(b, c, d, a, 0x4e0811a1, 21)
        a = Step4(a, b, c, d, 0xf7537e82, 6)
        d = Step4(d, a, b, c, 0xbd3af235, 10)
        c = Step4(c, d, a, b, 0x2ad7d2bb, 15)
        b = (Step4(b, c, d, a, 0xeb86d391, 21) + 0xefcdab89) % 0x100000000

        c = (c + 0x98badcfe) % 0x100000000
        a = floor(b / 0x10000) % 0x100 + floor(b / 0x1000000) % 0x100 * 0x100 + c % 0x100 * 0x10000 + floor(c / 0x100) % 0x100 * 0x1000000

        if (bEnabled) then
            jit.on()
        end

        return a
    end
end

-- From the Vector lib
do
    local VECTOR = FindMetaTable("Vector")

    function VECTOR:Right(vUp --[[= Vector(0, 0, 1)]])
        if (self[1] == 0 and self[2] == 0)then
            // pitch 90 degrees up/down from identity
            return Vector(0, -1, 0)
        end

        if (vUp == nil) then
            vUp = vector_up
        end

        local vRet = self:Cross(vUp)
        vRet:Normalize()

        return vRet
    end

    function VECTOR:Up(vUp --[[= Vector(0, 0, 1)]])
        if (self[1] == 0 and self[2] == 0)then
            return Vector(-self[3], 0, 0)
        end

        if (vUp == nil) then
            vUp = vector_up
        end

        local vRet = self:Cross(vUp)
        vRet = vRet:Cross(self)
        vRet:Normalize()

        return vRet
    end
end

-- From the entity lib
do
    local ENTITY = FindMetaTable("Entity")

    function ENTITY:IsBreakable()
        local sClass = self:GetClass()

        return sClass == "func_breakable" or sClass == "func_breakable_surf" or sClass == "func_physbox"
    end

    -- FIXME: Make debugoverlay display transparent
    function ENTITY:DrawHitBoxes(flDuration --[[= 0]])
        local iSet = self:GetHitboxSet()

        if (iSet ~= nil) then
            if (flDuration == nil) then
                flDuration = 0
            end

            for iGroup = 0, self:GetHitBoxGroupCount() - 1 do
                for iHitBox = 0, self:GetHitBoxCount(iGroup) - 1 do
                    local vPos, aRot = self:GetBonePosition(self:GetHitBoxBone(iHitBox, iGroup))
                    local vMins, vMaxs = self:GetHitBoxBounds(iHitBox, iGroup)
                    debugoverlay.BoxAngles(vPos, vMins, vMaxs, aRot, flDuration, color_debug)
                end
            end
        end
    end
end

local PLAYER = FindMetaTable("Player")

function PLAYER:GetMD5Seed()
    local iCommandNumber = self:GetCurrentCommand():CommandNumber() -- FIXME: Change to FrameNumber when it is finally binded serverside

    if (self.m_iMD5SeedSavedNumber ~= iCommandNumber) then
        self.m_iMD5SeedSavedNumber = iCommandNumber
        self.m_iMD5Seed = math.MD5Random(iCommandNumber)
    end

    return self.m_iMD5Seed
end

-- Equivalent of CBasePlayer::EyeVectors() before AngleVecotrs
function PLAYER:ActualEyeAngles()
    local pVehicle = self:GetVehicle()

    if (pVehicle:IsValid()) then
        local _, ang = pVehicle:GetVehicleViewPosition()

        return ang
    end

    return self:EyeAngles()
end

local vDefaultOffset = Vector(0, 0, -4)

function PLAYER:ComputeTracerStartPosition(vSrc, vOffset --[[= Vector(0, 0, -4)]], flForwardMul --[[= 16]], flRightMul --[[[= 2]])
    if (vOffset == nil) then
        vOffset = vDefaultOffset
    end

    if (flForwardMul == nil) then
        flForwardMul = 16
    end

    if (flRightMul == nil) then
        flRightMul = 2
    end

    // adjust tracer position for player
    local aEyes = self:ActualEyeAngles()

    local vForward = aEyes:Forward()
    vForward:Mul(flForwardMul)

    local vRight = aEyes:Right()
    vRight:Mul(flRightMul)

    vForward:Add(vSrc)
    vForward:Add(vOffset)
    vForward:Add(vRight)

    return vForward
end

AMMO_FORCE_DROP_IF_CARRIED = 0x1
AMMO_INTERPRET_PLRDAMAGE_AS_DAMAGE_TO_PLAYER = 0x2

FIRE_BULLETS_FIRST_SHOT_ACCURATE = 0x1 // Pop the first shot with perfect accuracy
FIRE_BULLETS_DONT_HIT_UNDERWATER = 0x2 // If the shot hits its target underwater, don't damage it
FIRE_BULLETS_ALLOW_WATER_SURFACE_IMPACTS = 0x4 // If the shot hits water surface, still call DoImpactEffect
-- The engine alerts NPCs by pushing a sound onto a static sound manager
-- However, this cannot be accessed from the Lua state
--FIRE_BULLETS_TEMPORARY_DANGER_SOUND = 0x8 // Danger sounds added from this impact can be stomped immediately if another is queued

local ai_debug_shoot_positions = GetConVar("ai_debug_shoot_positions")
local phys_pushscale = GetConVar("phys_pushscale")
local sv_showimpacts = CreateConVar("gs_weapons_showimpacts", "0", bit.bor(FCVAR_REPLICATED, FCVAR_ARCHIVE), "Shows client (red) and server (blue) bullet impact point (1=both, 2=client-only, 3=server-only)")
local sv_showpenetration = CreateConVar("gs_weapons_showpenetration", "0", bit.bor(FCVAR_REPLICATED, FCVAR_ARCHIVE), "Shows penetration trace (if applicable) when the weapon fires")
local sv_showplayerhitboxes = CreateConVar("gs_weapons_showplayerhitboxes", "0", bit.bor(FCVAR_REPLICATED, FCVAR_ARCHIVE), "Show lag compensated hitboxes for the specified player index whenever a player fires.")

local nWhizTracer = bit.bor(0x0002, 0x0001)
local iTracerCount = 0 -- Instance global to interact with FireBullets functions

local function Splash(vHitPos, bStartedInWater, bEndNotWater, vSrc, pWeapon, bFirstTimePredicted, iAmmoDamageType, iAmmoMinSplash, iAmmoMaxSplash, sSplashEffect)
    local trSplash = bStartedInWater and bEndNotWater and
        util.TraceLine({
            start = vHitPos,
            endpos = vSrc,
            mask = MASK_WATER
        })
    // See if the bullet ended up underwater + started out of the water
    or not (bStartedInWater or bEndNotWater) and
        util.TraceLine({
            start = vSrc,
            endpos = vHitPos,
            mask = MASK_WATER
        })

    if (trSplash and not (pWeapon and pWeapon.DoSplashEffect and pWeapon:DoSplashEffect(trSplash)) and bFirstTimePredicted) then
        local data = EffectData()
            data:SetOrigin(trSplash.HitPos)
            data:SetStart(vSrc)
            data:SetNormal(trSplash.HitNormal)
            data:SetSurfaceProp(trSplash.SurfaceProps)
            data:SetDamageType(iAmmoDamageType)
            data:SetHitBox(trSplash.HitBox)
            data:SetEntity(trSplash.Entity)

            if (SERVER) then
                data:SetEntIndex(trSplash.Entity:EntIndex())
            end

            data:SetScale(gs.random:RandomFloat(iAmmoMinSplash, iAmmoMaxSplash))

            if (bit.band(util.PointContents(trSplash.HitPos), CONTENTS_SLIME) ~= 0) then
                data:SetFlags(FX_WATER_IN_SLIME)
            end
        util.Effect(sSplashEffect, data) -- FIXME: Add settings to send in custom effects
    end
end

local function Impact(Weapon, iAmmoDamageType, bFirstTimePredicted, vSrc, tr, sImpactEffect, sRagdollImpactEffect)
    if (not (Weapon and Weapon.DoImpactEffect and Weapon:DoImpactEffect(tr, iAmmoDamageType))) then
        if (bFirstTimePredicted) then
            local data = EffectData()
                data:SetOrigin(tr.HitPos)
                data:SetStart(vSrc)
                data:SetNormal(tr.HitNormal)
                data:SetSurfaceProp(tr.SurfaceProps)
                data:SetDamageType(iAmmoDamageType)
                data:SetHitBox(tr.HitBox)
                data:SetEntity(tr.Entity)

                if (SERVER) then
                    data:SetEntIndex(tr.Entity:EntIndex())
                end

            util.Effect(sImpactEffect, data)
        end
    elseif (bFirstTimePredicted) then
        // We may not impact, but we DO need to affect ragdolls on the client
        -- FIXME: Should we?
        local data = EffectData()
            data:SetOrigin(tr.HitPos)
            data:SetStart(vSrc)
            data:SetNormal(tr.HitNormal)
            data:SetSurfaceProp(tr.SurfaceProps)
            data:SetDamageType(iAmmoDamageType)
            data:SetHitBox(tr.HitBox)
            data:SetEntity(tr.Entity)

            if (SERVER) then
                data:SetEntIndex(tr.Entity:EntIndex())
            end
        util.Effect(sRagdollImpactEffect, data)
    end
end

local function Damage(bDoDebugHit, bStartedWater, bEndNotWater, iFlags, iDamage, iPlayerDamage, iNPCDamage, iAmmoDamage, pAttacker, pInflictor,
    iAmmoDamageType, tr, Weapon, vShotDir, flAmmoForce, flForce, flPhysPush, iAmmoType, vSrc, fCallback, bFirstTimePredicted, bDrop, sImpactEffect, sRagdollImpactEffect)

    local vHitPos = tr.HitPos
    local pEntity = tr.Entity

    // draw server impact markers
    if (bDoDebugHit) then
        debugoverlay.Box(vHitPos, vector_debug_min, vector_debug_max, DEBUG_LENGTH, color_debug)
    end

    if (not bStartedWater and bEndNotWater or bit.band(iFlags, FIRE_BULLETS_DONT_HIT_UNDERWATER) == 0) then
        -- The engine considers this a float
        -- Even though no values assigned to it are
        -- FIXME: Update these typedefs
        local iActualDamage = iDamage

        // If we hit a player, and we have player damage specified, use that instead
        // Adrian: Make sure to use the currect value if we hit a vehicle the player is currently driving.
        -- We don't check for vehicle passengers since GMod has no C++ vehicles with them
        if (pEntity:IsPlayer()) then
            if (iPlayerDamage ~= 0) then
                iActualDamage = iPlayerDamage
            end
        elseif (pEntity:IsNPC()) then
            if (iNPCDamage ~= 0) then
                iActualDamage = iNPCDamage
            end
        -- https://github.com/Facepunch/garrysmod-requests/issues/760
        elseif (SERVER and pEntity:IsVehicle()) then
            local pDriver = pEntity:GetDriver()

            if (iPlayerDamage ~= 0 and pDriver:IsPlayer()) then
                iActualDamage = iPlayerDamage
            elseif (iNPCDamage ~= 0 and pDriver:IsNPC()) then
                iActualDamage = iNPCDamage
            end
        end

        if (iActualDamage == 0 and iAmmoDamage ~= 0) then
            iActualDamage = iAmmoDamage
        end

        // Damage specified by function parameter
        local info = DamageInfo()
            info:SetAttacker(pAttacker)
            info:SetInflictor(pInflictor)
            info:SetDamage(iActualDamage)
            info:SetDamageType(iAmmoDamageType)
            info:SetDamagePosition(vHitPos)
            info:SetDamageForce(vShotDir * flAmmoForce * flForce * flPhysPush)
            info:SetAmmoType(iAmmoType)
            info:SetReportedPosition(vSrc)
        pEntity:DispatchTraceAttack(info, tr, vShotDir)

        if (fCallback) then
            fCallback(pAttacker, tr, info)
        end

        if (bEndNotWater or bit.band(iFlags, FIRE_BULLETS_ALLOW_WATER_SURFACE_IMPACTS) ~= 0) then
            Impact(Weapon, iAmmoDamageType, bFirstTimePredicted, vSrc, tr, sImpactEffect, sRagdollImpactEffect)
        end
    end

    if (bDrop and SERVER) then
        // Make sure if the player is holding this, he drops it
        DropEntityIfHeld(pEntity)
    end
end

local function Tracer(bDebugShoot, vSrc, vFinalHit, bFirstTimePredicted, iTracerFreq, Weapon, self, iAmmoTracerType, iAmmoDamageType, sTracerName)
    if (bDebugShoot) then
        debugoverlay.Line(vSrc, vFinalHit, DEBUG_LENGTH, color_debug)
    end

    if (bFirstTimePredicted and iTracerFreq > 0) then
        if (iTracerCount % iTracerFreq == 0) then
            local data = EffectData()
                data:SetOrigin(vFinalHit)

                if (Weapon) then
                    local iAttachment = Weapon.GetMuzzleAttachment and Weapon:GetMuzzleAttachment() or 1
                    data:SetStart(Weapon.GetTracerOrigin and Weapon:GetTracerOrigin() or self:ComputeTracerStartPosition(vSrc, iAttachment))
                    data:SetAttachment(iAttachment)
                else
                    data:SetStart(self:ComputeTracerStartPosition(vSrc, 1))
                    data:SetAttachment(1)
                end

                data:SetDamageType(iAmmoDamageType)
                data:SetEntity(Weapon or self)

                if (SERVER) then
                    data:SetEntIndex((Weapon or self):EntIndex())
                end

                data:SetScale(0) -- FIXME: This was in the source code, but I'm pretty sure this is unnecessary + will potentially ruin custom effects
                data:SetFlags(iAmmoTracerType == TRACER_LINE_AND_WHIZ and nWhizTracer or 0x0002)
            util.Effect(sTracerName, data)
        end

        iTracerCount = iTracerCount + 1
    end
end

-- Defaults from ammodef.cpp
local tDefaultAmmoTable = {
    name = "",
    plydmg = 0,
    npcdmg = 0,
    maxcarry = 0,
    dmgtype = DMG_GENERIC,
    flags = 0,
    minsplash = 4,
    maxsplash = 8,
    tracer = TRACER_NONE,
    force = 0
}

function PLAYER:FireLuaBullets(tInfo)
    if (hook.Run("EntityFireBullets", self, tInfo) == false) then
        return
    end

    local bIsPlayer = self:IsPlayer()

    if (bIsPlayer) then
        self:LagCompensation(true)
    end

    local pWeapon = self:GetActiveWeapon()
    local bWeaponValid = pWeapon:IsValid()

    -- FireBullets info
    local iAmmoType

    if (tInfo.AmmoType == nil) then
        iAmmoType = -1
    elseif (isstring(tInfo.AmmoType)) then
        iAmmoType = game.GetAmmoID(tInfo.AmmoType)
    else
        iAmmoType = tInfo.AmmoType
    end

    local pAttacker = tInfo.Attacker or self
    local fCallback = tInfo.Callback
    local iDamage = tInfo.Damage or 0
    local vDir = tInfo.Dir and tInfo.Dir:GetNormal() or self:GetAimVector()
    local flDistance = tInfo.Distance or MAX_TRACE_LENGTH
    local Filter = tInfo.Filter or self
    local iFlags = tInfo.Flags or 0
    local flForce = tInfo.Force or 1
    local bHullTrace = tInfo.HullTrace

    if (bHullTrace == nil) then
        bHullTrace = true
    end

    local pInflictor = tInfo.Inflictor and tInfo.Inflictor:IsValid() and tInfo.Inflictor or bWeaponValid and pWeapon or self
    local iMask = tInfo.Mask or MASK_SHOT
    local iNPCDamage = tInfo.NPCDamage or 0
    local iNum = tInfo.Num or 1
    local iPlayerDamage = tInfo.PlayerDamage or 0
    local vSrc = tInfo.Src or self:GetShootPos()
    local iTracerFreq = tInfo.Tracer or 1
    local sTracerName = tInfo.TracerName or "Tracer"

    -- Effects
    local sSplashEffect = tInfo.SplashEffect or "gunshotsplash"
    local sImpactEffect = tInfo.ImpactEffect or "Impact"
    local sRagdollImpactEffect = tInfo.RagdollImpactEffect or "RagdollImpact"

    -- Ammo
    local tAmmoData = game.GetAmmoData(iAmmoType) or tDefaultAmmoTable
    local iAmmoFlags = tAmmoData.flags
    local flAmmoForce = tAmmoData.force
    local iAmmoDamageType = tAmmoData.dmgtype
    local iAmmoMinSplash = tAmmoData.minsplash
    local iAmmoMaxSplash = tAmmoData.maxsplash
    local iAmmoTracerType = tAmmoData.tracer

    local iAmmoNPCDamage = tAmmoData.npcdmg

    if (isstring(iAmmoNPCDamage)) then
        iAmmoNPCDamage = GetConVar(iAmmoNPCDamage):GetFloat()
    end

    local iAmmoPlayerDamage = tAmmoData.plydmg

    if (isstring(iAmmoPlayerDamage)) then
        iAmmoPlayerDamage = GetConVar(iAmmoPlayerDamage):GetFloat()
    end

    if (bit.band(iAmmoFlags, AMMO_INTERPRET_PLRDAMAGE_AS_DAMAGE_TO_PLAYER) ~= 0) then
        if (iPlayerDamage == 0) then
            iPlayerDamage = iAmmoPlayerDamage
        end

        if (iNPCDamage == 0) then
            iNPCDamage = iAmmoNPCDamage
        end
    end

    local iAmmoDamage = bIsPlayer and iAmmoPlayerDamage or iAmmoNPCDamage

    -- Loop values
    local bDrop = bit.band(iAmmoFlags, AMMO_FORCE_DROP_IF_CARRIED) ~= 0
    local bDebugShoot = ai_debug_shoot_positions:GetBool()
    local bFirstShotInaccurate = bit.band(iFlags, FIRE_BULLETS_FIRST_SHOT_ACCURATE) == 0
    local flPhysPush = phys_pushscale:GetFloat()
    local bShowPenetration = sv_showpenetration:GetBool()
    local bStartedInWater = bit.band(util.PointContents(vSrc), MASK_WATER) ~= 0
    local bFirstTimePredicted = IsFirstTimePredicted()
    local flSpreadBias, flFlatness, bNegBias, vFireBulletMax, vFireBulletMin, vSpreadRight, vSpreadUp, tEnts, iEntsLen

    // Wrap it for network traffic so it's the same between client and server
    local iSeed = self:GetMD5Seed() % 0x100 - 1

    -- Don't calculate stuff we won't end up using
    if (bFirstShotInaccurate or iNum ~= 1) then
        flSpreadBias = tInfo.SpreadBias or 0.5

        if (flSpreadBias > 1) then
            flSpreadBias = 1
            bNegBias = false
        elseif (flSpreadBias < -1) then
            flSpreadBias = -1
            bNegBias = true
        else
            bNegBias = flSpreadBias < 0

            if (bNegBias) then
                flSpreadBias = -flSpreadBias
            end
        end

        local vSpread = tInfo.Spread or vector_origin
        vSpreadRight = vSpread:Right()
        vSpreadRight:Mul(vSpread[1])
        vSpreadUp = vSpread:Up()
        vSpreadUp:Mul(vSpread[2])

        if (bHullTrace and iNum ~= 1) then
            local flHullSize = tInfo.HullSize
            vFireBulletMax = flHullSize and Vector(flHullSize, flHullSize, flHullSize) or Vector(3, 3, 3)
            vFireBulletMin = -vFireBulletMax
        end
    end

    local bDoDebugHit

    do
        //Adrian: visualize server/client player positions
        //This is used to show where the lag compesator thinks the player should be at.
        local iHitNum = sv_showplayerhitboxes:GetInt()

        if (iHitNum > 0) then
            local pLagPlayer = Player(iHitNum)

            if (pLagPlayer:IsValid()) then
                pLagPlayer:DrawHitBoxes(DEBUG_LENGTH)
            end
        end

        iHitNum = sv_showimpacts:GetInt()
        bDoDebugHit = iHitNum == 1 or (CLIENT and iHitNum == 2) or (SERVER and iHitNum == 3)
    end

    for iShot = 1, iNum do
        local vShotDir
        iSeed = iSeed + 1 // use new seed for next bullet
        gs.random:SetSeed(iSeed) // init random system with this seed

        // If we're firing multiple shots, and the first shot has to be ba on target, ignore spread
        if (bFirstShotInaccurate or iShot ~= 1) then
            local x
            local y
            local z

            repeat
                x = gs.random:RandomFloat(-flSpreadBias, flSpreadBias) + gs.random:RandomFloat(flSpreadBias - 1, 1 - flSpreadBias)
                y = gs.random:RandomFloat(-flSpreadBias, flSpreadBias) + gs.random:RandomFloat(flSpreadBias - 1, 1 - flSpreadBias)

                if (bNegBias) then
                    x = x < 0 and -(1 + x) or 1 - x
                    y = y < 0 and -(1 + y) or 1 - y
                end

                z = x * x + y * y
            until (z <= 1)

            vShotDir = vDir + x * vSpreadRight + y * vSpreadUp
            vShotDir:Normalize()
        else
            vShotDir = vDir
        end

        local bHitGlass
        local vEnd = vSrc + vShotDir * flDistance
        local vNewSrc = vSrc
        local vFinalHit

        repeat
            local tr = bHullTrace and iShot % 2 == 0 and
                // Half of the shotgun pellets are hulls that make it easier to hit targets with the shotgun.
                util.TraceHull({
                    start = vNewSrc,
                    endpos = vEnd,
                    mins = vFireBulletMin,
                    maxs = vFireBulletMax,
                    mask = iMask,
                    filter = Filter
                })
            or
                util.TraceLine({
                    start = vNewSrc,
                    endpos = vEnd,
                    mask = iMask,
                    filter = Filter
                })

            --[[if (SERVER) then
                if (bStartedInWater) then
                    local flLengthSqr = vSrc:DistToSqr(tr.HitPos)

                    if (flLengthSqr > SHOT_UNDERWATER_BUBBLE_DIST * SHOT_UNDERWATER_BUBBLE_DIST) then
                        util.BubbleTrail(self:ComputeTracerStartPosition(vSrc),
                        vSrc + SHOT_UNDERWATER_BUBBLE_DIST * vShotDir,
                        WATER_BULLET_BUBBLES_PER_INCH * SHOT_UNDERWATER_BUBBLE_DIST)
                    else
                        local flLength = math.sqrt(flLengthSqr) - 0.1
                        util.BubbleTrail(self:ComputeTracerStartPosition(vSrc),
                        vSrc + flLength * vShotDir,
                        SHOT_UNDERWATER_BUBBLE_DIST * flLength)
                    end
                end

                // Now hit all triggers along the ray that respond to shots...
                // Clip the ray to the first collided solid returned from traceline
                -- https://github.com/Facepunch/garrysmod-requests/issues/755
                local triggerInfo = DamageInfo()
                    triggerInfo:SetAttacker(pAttacker)
                    triggerInfo:SetInflictor(pAttacker)
                    triggerInfo:SetDamage(iDamage)
                    triggerInfo:SetDamageType(iAmmoDamageType)
                    triggerInfo:CalculateBulletDamageForce(sAmmoType, vShotDir, tr.HitPos, tr.HitPos, flForce)
                    triggerInfo:SetAmmoType(iAmmoType)
                triggerInfo:TraceAttackToTriggers(triggerInfo, vSrc, tr.HitPos, vShotDir)
            end]]

            local vHitPos = tr.HitPos
            vFinalHit = vHitPos

            local bEndNotWater = bit.band(util.PointContents(vHitPos), MASK_WATER) == 0
            Splash(vHitPos, bStartedInWater, bEndNotWater, vSrc, bWeaponValid and pWeapon, bFirstTimePredicted, iAmmoDamageType, iAmmoMinSplash, iAmmoMaxSplash, sSplashEffect)

            if (not tr.Hit or tr.HitSky) then
                break // we didn't hit anything, stop tracing shoot
            end

            Damage(bDoDebugHit, bStartedWater, bEndNotWater, iFlags, iDamage, iPlayerDamage, iNPCDamage, iAmmoDamage, pAttacker, pInflictor, iAmmoDamageType,
                tr, bWeaponValid and pWeapon, vShotDir, flAmmoForce, flForce, flPhysPush, iAmmoType, vSrc, fCallback, bFirstTimePredicted, bDrop, sImpactEffect, sRagdollImpactEffect)

            // do damage, paint decals
            -- https://github.com/Facepunch/garrysmod-issues/issues/2741
            local pEntity = tr.Entity
            bHitGlass = --[[tr.MatType == MAT_GLASS]] pEntity:IsBreakable() and not pEntity:HasSpawnFlags(SF_BREAK_NO_BULLET_PENETRATION)

            // See if we hit glass
            // Query the func_breakable for whether it wants to allow for bullet penetration
            if (bHitGlass) then
                if (tEnts == nil) then
                    tEnts = ents.GetAll()
                    iEntsLen = #tEnts
                end

                local bReplace = false

                -- Trace for only the entity we hit
                for i = iEntsLen, 1, -1 do
                    if (tEnts[i] == pEntity) then
                        tEnts[i] = tEnts[iEntsLen]
                        tEnts[iEntsLen] = nil
                        bReplace = true

                        break
                    end
                end

                util.TraceLine({
                    start = vEnd,
                    endpos = vHitPos,
                    mask = iMask,
                    filter = tEnts,
                    ignoreworld = true,
                    output = tr
                })

                // bullet did penetrate object, exit Decal
                Impact(bWeaponValid and pWeapon, iAmmoDamageType, bFirstTimePredicted, vSrc, tr, sImpactEffect, sRagdollImpactEffect)

                vNewSrc = tr.HitPos

                if (bShowPenetration) then
                    debugoverlay.Line(vHitPos, vNewSrc, DEBUG_LENGTH, color_altdebug)
                end

                if (bDoDebugHit) then
                    debugoverlay.Box(vNewSrc, vector_debug_min, vector_debug_max, DEBUG_LENGTH, color_altdebug)
                end

                -- Should never be false
                if (bReplace) then
                    tEnts[iEntsLen] = pEntity
                end
            end
        until (not bHitGlass)

        Tracer(bDebugShoot, vSrc, vFinalHit, bFirstTimePredicted, iTracerFreq, bWeaponValid and pWeapon, self, iAmmoTracerType, iAmmoDamageType, sTracerName)
    end

    if (bIsPlayer) then
        self:LagCompensation(false)
    end
end

local tMaterialParameters = {
    [MAT_METAL] = {
        Penetration = 0.5,
        Damage = 0.3
    },
    [MAT_DIRT] = {
        Penetration = 0.5,
        Damage = 0.3
    },
    [MAT_CONCRETE] = {
        Penetration = 0.4,
        Damage = 0.25
    },
    [MAT_GRATE] = {
        Penetration = 1,
        Damage = 0.99
    },
    [MAT_VENT] = {
        Penetration = 0.5,
        Damage = 0.45
    },
    [MAT_TILE] = {
        Penetration = 0.65,
        Damage = 0.3
    },
    [MAT_COMPUTER] = {
        Penetration = 0.4,
        Damage = 0.45
    },
    [MAT_WOOD] = {
        Penetration = 1,
        Damage = 0.6
    },
    [MAT_GLASS] = {
        Penetration = 1,
        Damage = 0.99
    }
}

local tDoublePenetration = {
    [MAT_WOOD] = true,
    [MAT_METAL] = true,
    [MAT_GRATE] = true,
    [MAT_GLASS] = true
}

local MASK_HITBOX = bit.bor(MASK_SOLID, CONTENTS_DEBRIS, CONTENTS_HITBOX)

function PLAYER:FireCSSBullets(tInfo)
    if (hook.Run("EntityFireBullets", self, tInfo) == false) then
        return
    end

    local bIsPlayer = self:IsPlayer()

    if (bIsPlayer) then
        self:LagCompensation(true)
    end

    local pWeapon = self:GetActiveWeapon()
    local bWeaponValid = pWeapon:IsValid()

    -- FireCSSBullets info
    local iAmmoType

    if (tInfo.AmmoType == nil) then
        iAmmoType = -1
    elseif (isstring(tInfo.AmmoType)) then
        iAmmoType = game.GetAmmoID(tInfo.AmmoType)
    else
        iAmmoType = tInfo.AmmoType
    end

    local pAttacker = tInfo.Attacker and tInfo.Attacker:IsValid() and tInfo.Attacker or self
    local fCallback = tInfo.Callback
    local iDamage = tInfo.Damage or 0
    local flDecayRate = tInfo.DecayRate or 1/500
    local vDir = tInfo.Dir and tInfo.Dir:GetNormal() or self:GetAimVector()
    local flDistance = tInfo.Distance or MAX_TRACE_LENGTH
    local flExitMaxDistance = tInfo.ExitMaxDistance or 128
    local flExitStepSize = tInfo.ExitStepSize or 24

    local bFilterIsFunction
    local iFilterEnd
    local Filter = tInfo.Filter

    -- Yes, this is dirty
    -- But this prevents tables from being created when it's not necessary
    -- Also supports functional filters
    if (isentity(Filter)) then
        iFilterEnd = -1
        bFilterIsFunction = false
    elseif (istable(Filter)) then
        -- Length of the table will be found if penetration happens
        --iFilterEnd = #Filter
        bFilterIsFunction = false
    elseif (isfunction(Filter)) then
        bFilterIsFunction = true
    else
        Filter = self
        iFilterEnd = -1
        bFilterIsFunction = false
    end

    local iFlags = tInfo.Flags or 0
    local flForce = tInfo.Force or 1
    --local flHitboxTolerance = tInfo.HitboxTolerance or 40
    local bHullTrace = tInfo.HullTrace or false
    local pInflictor = tInfo.Inflictor and tInfo.Inflictor:IsValid() and tInfo.Inflictor or bWeaponValid and pWeapon or self
    local iMask = tInfo.Mask or MASK_HITBOX
    local iNPCDamage = tInfo.NPCDamage or 0
    local iNum = tInfo.Num or 1
    local iPenetration = tInfo.Penetration or 0
    local iPlayerDamage = tInfo.PlayerDamage or 0
    local flRangeModifier = tInfo.RangeModifier or 1
    local vSrc = tInfo.Src or self:GetShootPos()
    local iTracerFreq = tInfo.Tracer or 1
    local sTracerName = tInfo.TracerName or "Tracer"

    -- Effects
    local sSplashEffect = tInfo.SplashEffect or "gunshotsplash"
    local sImpactEffect = tInfo.ImpactEffect or "Impact"
    local sRagdollImpactEffect = tInfo.RagdollImpactEffect or "RagdollImpact"

    -- Ammo
    local tAmmoData = game.GetAmmoData(iAmmoType) or tDefaultAmmoTable
    local iAmmoFlags = tAmmoData.flags
    local flAmmoForce = tAmmoData.force
    local iAmmoDamageType = tAmmoData.dmgtype
    local iAmmoMinSplash = tAmmoData.minsplash
    local iAmmoMaxSplash = tAmmoData.maxsplash
    local iAmmoTracerType = tAmmoData.tracer

    local iAmmoNPCDamage = tAmmoData.npcdmg

    if (isstring(iAmmoNPCDamage)) then
        iAmmoNPCDamage = GetConVar(iAmmoNPCDamage):GetFloat()
    end

    local iAmmoPlayerDamage = tAmmoData.plydmg

    if (isstring(iAmmoPlayerDamage)) then
        iAmmoPlayerDamage = GetConVar(iAmmoPlayerDamage):GetFloat()
    end

    -- FIXME: These should be tied to ammo types
    local flPenetrationDistance = tInfo.PenetrationDistance or 0
    local flPenetrationPower = tInfo.PenetrationPower or 0

    -- Loop values
    local bDrop = bit.band(iAmmoFlags, AMMO_FORCE_DROP_IF_CARRIED) ~= 0
    local bDebugShoot = ai_debug_shoot_positions:GetBool()
    local bFirstShotInaccurate = bit.band(iFlags, FIRE_BULLETS_FIRST_SHOT_ACCURATE) == 0
    local flPhysPush = phys_pushscale:GetFloat()
    local bShowPenetration = sv_showpenetration:GetBool()
    local bStartedInWater = bit.band(util.PointContents(vSrc), MASK_WATER) ~= 0
    local bFirstTimePredicted = IsFirstTimePredicted()
    local flSpreadBias, vShootRight, vShootUp, vFireBulletMin, vFireBulletMax, tEnts, iEntsLen

    // Wrap it for network traffic so it's the same between client and server
    local iSeed = self:GetMD5Seed() % 0x100

    -- Don't calculate stuff we won't end up using
    if (bFirstShotInaccurate or iNum ~= 1) then
        local vSpread = tInfo.Spread or vector_origin
        flSpreadBias = tInfo.SpreadBias or 0.5
        vShootRight = vDir:Right()
        vShootRight:Mul(vSpread[1])
        vShootUp = vDir:Up()
        vShootUp:Mul(vSpread[2])

        if (bHullTrace and iNum ~= 1) then
            local flHullSize = tInfo.HullSize
            vFireBulletMax = flHullSize and Vector(flHullSize, flHullSize, flHullSize) or Vector(3, 3, 3)
            vFireBulletMin = -vFireBulletMax
        end
    end

    local bDoDebugHit

    do
        //Adrian: visualize server/client player positions
        //This is used to show where the lag compesator thinks the player should be at.
        local iHitNum = sv_showplayerhitboxes:GetInt()

        if (iHitNum > 0) then
            local pLagPlayer = Player(iHitNum)

            if (pLagPlayer:IsValid()) then
                pLagPlayer:DrawHitBoxes(DEBUG_LENGTH)
            end
        end

        iHitNum = sv_showimpacts:GetInt()
        bDoDebugHit = iHitNum == 1 or (CLIENT and iHitNum == 2) or (SERVER and iHitNum == 3)
    end

    for iShot = 1, iNum do
        local vShotDir
        iSeed = iSeed + 1 // use new seed for next bullet
        gs.random:SetSeed(iSeed) // init random system with this seed

        -- Loop values
        local flCurrentDamage = iDamage // damage of the bullet at it's current trajectory
        local flCurrentPlayerDamage = iPlayerDamage
        local flCurrentNPCDamage = iNPCDamage
        local flCurrentDistance = 0 // distance that the bullet has traveled so far
        local vNewSrc = vSrc
        local vFinalHit

        // add the spray
        if (bFirstShotInaccurate or iShot ~= 1) then
            vShotDir = vDir + vShootRight * (gs.random:RandomFloat(-flSpreadBias, flSpreadBias) + gs.random:RandomFloat(-flSpreadBias, flSpreadBias))
            + vShootUp * (gs.random:RandomFloat(-flSpreadBias, flSpreadBias) + gs.random:RandomFloat(-flSpreadBias, flSpreadBias))
            vShotDir:Normalize()
        else
            vShotDir = vDir
        end

        local vEnd = vNewSrc + vShotDir * flDistance

        repeat
            local tr = bHullTrace and iShot % 2 == 0 and
                // Half of the shotgun pellets are hulls that make it easier to hit targets with the shotgun.
                util.TraceHull({
                    start = vNewSrc,
                    endpos = vEnd,
                    mins = vFireBulletMin,
                    maxs = vFireBulletMax,
                    mask = iMask,
                    filter = Filter
                })
            or
                util.TraceLine({
                    start = vNewSrc,
                    endpos = vEnd,
                    mask = iMask,
                    filter = Filter
                })

            // Check for player hitboxes extending outside their collision bounds
            --util.ClipTraceToPlayers(tr, vNewSrc, vEnd + vShotDir * flHitboxTolerance, Filter, iMask)

            local vHitPos = tr.HitPos
            vFinalHit = vHitPos

            local bEndNotWater = bit.band(util.PointContents(vHitPos), MASK_WATER) == 0
            Splash(vHitPos, bStartedInWater, bEndNotWater, vSrc, bWeaponValid and pWeapon, bFirstTimePredicted, iAmmoDamageType, iAmmoMinSplash, iAmmoMaxSplash, sSplashEffect)

            if (not tr.Hit or tr.HitSky) then
                break // we didn't hit anything, stop tracing shoot
            end

            /************* MATERIAL DETECTION ***********/
            -- https://github.com/Facepunch/garrysmod-requests/issues/923
            local iEnterMaterial = tr.MatType

            -- https://github.com/Facepunch/garrysmod-requests/issues/787
            // since some railings in de_inferno are CONTENTS_GRATE but CHAR_TEX_CONCRETE, we'll trust the
            // CONTENTS_GRATE and use a high damage modifier.
            // If we're a concrete grate (TOOLS/TOOLSINVISIBLE texture) allow more penetrating power.
            local bHitGrate = iEnterMaterial == MAT_GRATE or bit.band(util.PointContents(vHitPos), CONTENTS_GRATE) ~= 0

            // calculate the damage based on the distance the bullet travelled.
            flCurrentDistance = flCurrentDistance + tr.Fraction * flDistance
            local flDecay = flRangeModifier ^ (flCurrentDistance * flDecayRate)
            flCurrentDamage = flCurrentDamage * flDecay
            flCurrentPlayerDamage = flCurrentPlayerDamage * flDecay
            flCurrentNPCDamage = flCurrentNPCDamage * flDecay

            Damage(bDoDebugHit, bStartedWater, bEndNotWater, iFlags, flCurrentDamage, flCurrentPlayerDamage, flCurrentNPCDamage, bIsPlayer and iAmmoPlayerDamage or iAmmoNPCDamage, pAttacker,
                pInflictor, iAmmoDamageType, tr, bWeaponValid and pWeapon, vShotDir, flAmmoForce, flForce, flPhysPush, iAmmoType, vSrc, fCallback, bFirstTimePredicted, bDrop, sImpactEffect, sRagdollImpactEffect)

            // check if we reach penetration distance, no more penetrations after that
            if (flCurrentDistance > flPenetrationDistance and iPenetration > 0) then
                iPenetration = 0
            end

            // check if bullet can penetrate another entity
            // If we hit a grate with iPenetration == 0, stop on the next thing we hit
            if (iPenetration == 0 and not bHitGrate or iPenetration < 0) then
                break
            end

            local pEntity = tr.Entity

            if (pEntity:IsBreakable() and pEntity:HasSpawnFlags(SF_BREAK_NO_BULLET_PENETRATION)) then
                break // no, stop
            end

            if (tEnts == nil) then
                tEnts = ents.GetAll()
                iEntsLen = #tEnts
            end

            if (pEntity:IsWorld()) then
                local flExitDistance = 0

                local tr = tr
                local tTrace = {
                    mask = iMask,
                    filter = tEnts,
                    output = tr
                }

                // try to penetrate object, maximum penetration is 128 inch
                while (flExitDistance < flExitMaxDistance) do
                    flExitDistance = math.min(flExitMaxDistance, flExitDistance + flExitStepSize)

                    local vHit = vHitPos + flExitDistance * vShotDir
                    tTrace.start = vHit
                    tTrace.endpos = vHit
                    util.TraceLine(tTrace)

                    if (not tr.Hit) then
                        // found first free point
                        goto PositionFound
                    end
                end

                -- Nowhere to penetrate
                do break end

                ::PositionFound::

                tTrace.endpos = vHitPos
                util.TraceLine(tTrace)
            else
                local bReplace = false

                -- Trace for only the entity we hit
                for i = iEntsLen, 1, -1 do
                    if (tEnts[i] == pEntity) then
                        tEnts[i] = tEnts[iEntsLen]
                        tEnts[iEntsLen] = nil
                        bReplace = true

                        break
                    end
                end

                util.TraceLine({
                    start = vEnd,
                    endpos = vHitPos,
                    mask = iMask,
                    filter = tEnts,
                    ignoreworld = true,
                    output = tr
                })

                -- Should never be false
                if (bReplace) then
                    tEnts[iEntsLen] = pEntity
                end
            end

            vNewSrc = tr.HitPos
            vEnd = vNewSrc + vShotDir * flDistance

            if (bShowPenetration) then
                debugoverlay.Line(vHitPos, vNewSrc, DEBUG_LENGTH, color_altdebug)
            end

            local iExitMaterial = tr.MatType
            local tMatParams = tMaterialParameters[iEnterMaterial]
            local flPenetrationModifier = bHitGrate and 1 or tMatParams and tMatParams.Penetration or 1
            local flDamageModifier = bHitGrate and 0.99 or tMatParams and tMatParams.Damage or 0.5
            local flTraceDistance = (vNewSrc - vHitPos):LengthSqr()

            // if enter & exit point is wood or metal we assume this is
            // a hollow crate or barrel and give a penetration bonus
            if (bHitGrate and (iExitMaterial == MAT_GRATE or bit.band(util.PointContents(tr.HitPos), CONTENTS_GRATE) ~= 0) or iEnterMaterial == iExitMaterial and tDoublePenetration[iExitMaterial]) then
                flPenetrationModifier = flPenetrationModifier * 2
            end

            local flPenetrationDistance = flPenetrationPower * flPenetrationModifier

            // check if bullet has enough power to penetrate this distance for this material
            if (flTraceDistance > flPenetrationDistance * flPenetrationDistance) then
                break // bullet hasn't enough power to penetrate this distance
            end

            if (bDoDebugHit) then
                debugoverlay.Box(tr.HitPos, vector_debug_min, vector_debug_max, DEBUG_LENGTH, color_altdebug)
            end

            // bullet did penetrate object, exit Decal
            Impact(bWeaponValid and pWeapon, iAmmoDamageType, bFirstTimePredicted, vSrc, tr, sImpactEffect, sRagdollImpactEffect)

            // penetration was successful
            flTraceDistance = math.sqrt(flTraceDistance)

            // setup new start end parameters for successive trace
            flPenetrationPower = flPenetrationPower - flTraceDistance / flPenetrationModifier
            flCurrentDistance = flCurrentDistance + flTraceDistance

            // reduce damage power each time we hit something other than a grate
            flCurrentDamage = flCurrentDamage * flDamageModifier
            flDistance = (flDistance - flCurrentDistance) * 0.5

            // reduce penetration counter
            iPenetration = iPenetration - 1

            -- Can't hit players more than once
            if (pEntity:IsPlayer() or pEntity:IsNPC()) then
                if (bFilterIsFunction) then
                    local fOldFilter = Filter
                    Filter = function(pTest)
                        return fOldFilter(pTest) and pTest ~= pEntity
                    end
                elseif (iFilterEnd == -1) then
                    Filter = {Filter, pEntity}
                    iFilterEnd = 2
                else
                    iFilterEnd = (iFilterEnd or #Filter) + 1
                    Filter[iFilterEnd] = pEntity
                end
            end
        until (flCurrentDamage <= 0)

        Tracer(bDebugShoot, vSrc, vFinalHit, bFirstTimePredicted, iTracerFreq, bWeaponValid and pWeapon, self, iAmmoTracerType, iAmmoDamageType, sTracerName)
    end

    if (bIsPlayer) then
        self:LagCompensation(false)
    end
end