C4 Rework (TTT-2#1739)

Now scales C4 damage with radius and gives consistent damage through
walls regardless of line of sight.
Relates to TTT-2#1729 and TTT-2#1730 although the calculation for proper Killzone
is not yet included, but the safe and killzones are now 100% correct.

---------

Co-authored-by: Tim Goll <[email protected]>

CHANGELOG.md

@@ -15,6 +15,7 @@ All notable changes to TTT2 will be documented here. Inspired by [keep a changel
 - Added a menu to allow admins to inspect, in detail, how and why roles are distributed as they are (by @nike4613)
 - Added option to enable team name next to role name on the HUD (by @milkwxter)
 - Added score event for winning with configurable role parameter (by @MrXonte)
+- Added ExplosiveSphereDamage game effect for easy calculation of explosion damage through walls (by @MrXonte)
 
 ### Fixed
 
@@ -39,6 +40,7 @@ All notable changes to TTT2 will be documented here. Inspired by [keep a changel
 - Fixed a few errors in shop error messages (by @Histalek)
 - Fixed `markerVision`'s registry table being able to contain duplicate obsolete entries, thus fixing potential syncing issues with markers (by @TW1STaL1CKY)
 - Fixed issue in new Ammo dropping that could cause an error when dropping for modified weapon bases. (by @MrXonte)
+- Fixed C4 not showing the correct inflictor when the player is killed (by @TimGoll)
 
 ### Changed
 
@@ -60,6 +62,7 @@ All notable changes to TTT2 will be documented here. Inspired by [keep a changel
 - Moved all role-related admin options into the "Roles" menu (by @nike4613)
 - Improved description of role layering (by @nike4613)
 - Improved the role layering menu by showing which role is enabled and which is disabled (by @TimGoll)
+- Reworked C4 damage calculation with new gameEffect ExplosiveSphereDamage (by @MrXonte)
 
 ## [v0.14.0b](https://github.com/TTT-2/TTT2/tree/v0.14.0b) (2024-09-20)
 

gamemodes/terrortown/entities/entities/ttt_c4/shared.lua

@@ -109,7 +109,7 @@ function ENT:Initialize()
     end
 
     if not self:GetRadius() then
-        self:SetRadius(1000)
+        self:SetRadius(1500)
     end
 
     if not self:GetDmg() then
@@ -145,55 +145,6 @@ function ENT.SafeWiresForTime(t)
     end
 end
 
----
--- @param Entity dmgowner
--- @param Vector center
--- @param number radius
--- @realm shared
-function ENT:SphereDamage(dmgowner, center, radius)
-    -- It seems intuitive to use FindInSphere here, but that will find all ents
-    -- in the radius, whereas there exist only ~16 players. Hence it is more
-    -- efficient to cycle through all those players and do a Lua-side distance
-    -- check.
-
-    local r = radius * radius -- square so we can compare with dot product directly
-
-    -- pre-declare to avoid realloc
-    local d = 0.0
-    local diff = nil
-    local dmg = 0
-
-    local plys = playerGetAll()
-    for i = 1, #plys do
-        local ply = plys[i]
-        if ply:Team() ~= TEAM_TERROR then
-            continue
-        end
-
-        -- dot of the difference with itself is distance squared
-        diff = center - ply:GetPos()
-        d = diff:Dot(diff)
-
-        if d >= r then
-            continue
-        end
-
-        -- deadly up to a certain range, then a quick falloff within 100 units
-        d = math.max(0, math.sqrt(d) - 490)
-        dmg = -0.01 * (d * d) + 125
-
-        local dmginfo = DamageInfo()
-        dmginfo:SetDamage(dmg)
-        dmginfo:SetAttacker(dmgowner)
-        dmginfo:SetInflictor(self)
-        dmginfo:SetDamageType(DMG_BLAST)
-        dmginfo:SetDamageForce(center - ply:GetPos())
-        dmginfo:SetDamagePosition(ply:GetPos())
-
-        ply:TakeDamageInfo(dmginfo)
-    end
-end
-
 local c4boom = Sound("c4.explode")
 
 ---
@@ -244,11 +195,14 @@ function ENT:Explode(tr)
             r_outer = r_outer / 2.5
         end
 
-        -- damage through walls
-        self:SphereDamage(dmgowner, pos, r_inner)
-
-        -- explosion damage
-        util.BlastDamage(self, dmgowner, pos, r_outer, self:GetDmg())
+        gameEffects.ExplosiveSphereDamage(
+            dmgowner,
+            ents.Create("weapon_ttt_c4"),
+            self:GetDmg(),
+            pos,
+            r_outer,
+            r_inner
+        )
 
         local effect = EffectData()
         effect:SetStart(pos)
@@ -903,9 +857,24 @@ else -- CLIENT
 
         local color = COLOR_WHITE
 
-        if mvData:GetEntityDistance() > ent:GetRadius() then
+        --Calculating damage falloff with inverse square method
+        --100% from 0 to innerRadius
+        --100% to 0% from innerRadius to outerRadius
+        --0% from outerRadius to infinity
+        local dFraction = math.max(
+            1.0
+                - math.max(
+                    (mvData:GetEntityDistance() - ent:GetRadiusInner())
+                        / (ent:GetRadius() - ent:GetRadiusInner()),
+                    0.0
+                ),
+            0.0
+        )
+        local dmg = math.Round(ent:GetDmg() * dFraction * dFraction)
+
+        if dmg <= 0 then
             mvData:AddDescriptionLine(TryT("c4_marker_vision_safe_zone"), COLOR_GREEN)
-        elseif mvData:GetEntityDistance() > ent:GetRadiusInner() then
+        elseif dmg < 100 then
             mvData:AddDescriptionLine(TryT("c4_marker_vision_damage_zone"), COLOR_ORANGE)
 
             color = COLOR_ORANGE

lua/ttt2/libraries/game_effects.lua

@@ -148,6 +148,76 @@ function gameEffects.RadiusDamage(dmginfo, pos, radius, inflictor)
     end
 end
 
+-- Creates explosion damage in a sphere through walls. Very useful for making explosives that aren't line of sight based.
+-- @param Player attacker The player that causes this explosion.
+-- @param Entity inflictor The entity that causes this explosion.
+-- @param number damage The maximum damage done by this explosion.
+-- @param Vector origin The center of the explosion.
+-- @param number outerRadius The outer border for the explosion damage and its falloff.
+-- @param number innerRadius The inner border for the explosion damage where falloff starts.
+-- @internal
+-- @realm server
+function gameEffects.ExplosiveSphereDamage(
+    attacker,
+    inflictor,
+    damage,
+    origin,
+    outerRadius,
+    innerRadius
+)
+    -- It seems intuitive to use FindInSphere here, but that will find all ents
+    -- in the radius, whereas there exist only ~16 players. Hence it is more
+    -- efficient to cycle through all those players and do a Lua-side distance
+    -- check.
+
+    if outerRadius < innerRadius then
+        ErrorNoHalt(
+            "[Game Effects Explosive Sphere Damage] Outer radius too high! Setting both radi to outer radius."
+        )
+        innerRadius = outerRadius
+    end
+
+    -- pre-declare to avoid realloc
+    local d = 0.0
+    local dFraction = 0.0
+    local diff = nil
+    local dmg = 0
+    local radiDiff = (outerRadius - innerRadius)
+    local plys = player.GetAll()
+    for i = 1, #plys do
+        local ply = plys[i]
+
+        if not IsValid(ply) or not ply:IsTerror() then
+            continue
+        end
+
+        diff = origin - (ply:GetPos() + ply:OBBCenter())
+        --we are using Length on purpose here. We would need a sqrt somewhere anyway and with this we dont need to square the radi
+        d = diff:Length()
+        --we now turn this into a % of damage based of the value of d
+        --100% from 0 to innerRadius
+        --100% to 0% from innerRadius to outerRadius
+        --<0% from outerRadius to infinity
+        dFraction = 1.0 - math.max((d - innerRadius) / radiDiff, 0.0)
+
+        --Next Iteration if we are outside the radius
+        if dFraction < 0.0 then
+            continue
+        end
+
+        dmg = math.Round(damage * dFraction * dFraction)
+
+        local dmginfo = DamageInfo()
+        dmginfo:SetDamage(dmg)
+        dmginfo:SetAttacker(attacker)
+        dmginfo:SetInflictor(inflictor)
+        dmginfo:SetDamageType(DMG_BLAST)
+        dmginfo:SetDamageForce(diff)
+        dmginfo:SetDamagePosition(ply:GetPos() + ply:OBBCenter())
+        ply:TakeDamageInfo(dmginfo)
+    end
+end
+
 -- vFIRE INTEGRATION
 
 if SERVER then