Salvation Undershoot Fix (FAForever#6185)

changelog/snippets/fix.6185.md

@@ -0,0 +1 @@
+(#6185) Fix Salvation Undershooting - reworks Salvation projectile code to not drop short and use blueprint values for speed and fragment spread

engine/Core/Blueprints/ProjectileBlueprint.lua

@@ -138,4 +138,6 @@
 ---@field RealisticOrdinance boolean
 --- bombs that always drop stright down
 ---@field StraightDownOrdinance boolean
+--- for projectiles that spawn spreads of sub-projectiles, how large the impact radius should be
+---@field FragmentRadius number
 ---@field OnLostTargetLifetime? number

engine/Sim/Projectile.lua

@@ -170,6 +170,7 @@ end
 ---@param velX number
 ---@param velY? number
 ---@param velZ? number
+---@return Projectile
 function Projectile:SetVelocity(velX, velY, velZ)
 end
 

lua/sim/weapons/DefaultProjectileWeapon.lua

@@ -402,7 +402,7 @@ DefaultProjectileWeapon = ClassWeapon(Weapon) {
                 end
                 self.EconDrain = CreateEconomyEvent(self.unit, nrgReq, 0, time)
                 self.FirstShot = true
-                self.unit:ForkThread(self.EconomyDrainThread)
+                ForkThread(self.EconomyDrainThread, self)
             end
         end
     end,

projectiles/AIFFragmentationSensorShell01/AIFFragmentationSensorShell01_proj.bp

@@ -39,13 +39,14 @@ ProjectileBlueprint {
     Physics = {
         DestroyOnWater = true,
         DetonateBelowHeight = 45,
-        InitialSpeed = 14.6,
+        InitialSpeed = 16,
         InitialSpeedRange = 3,
         InitialSpeedReduceDistance = 30,
         LeadTarget = false,
         TurnRate = 360,
         VelocityAlign = true,
         Fragments = 6,
-        FragmentId = '/projectiles/AIFFragmentationSensorShell02/AIFFragmentationSensorShell02_proj.bp'
+        FragmentId = '/projectiles/AIFFragmentationSensorShell02/AIFFragmentationSensorShell02_proj.bp',
+        FragmentRadius = 7,
     },
 }

projectiles/AIFFragmentationSensorShell01/AIFFragmentationSensorShell01_script.lua

@@ -8,6 +8,15 @@ local EffectTemplate = import("/lua/effecttemplates.lua")
 local AArtilleryFragmentationSensorShellProjectile = import("/lua/aeonprojectiles.lua").AArtilleryFragmentationSensorShellProjectile
 local RandomFloat = import("/lua/utilities.lua").GetRandomFloat
 
+local MathSqrt = math.sqrt
+local MathPow = math.pow
+local MathPi = math.pi
+local MathSin = math.sin
+local MathCos = math.cos
+
+-- Gravitational constant
+local g = -4.9
+
 ---@class AIFFragmentationSensorShell01 : AArtilleryFragmentationSensorShellProjectile
 AIFFragmentationSensorShell01 = ClassProjectile(AArtilleryFragmentationSensorShellProjectile) {
 
@@ -23,33 +32,50 @@ AIFFragmentationSensorShell01 = ClassProjectile(AArtilleryFragmentationSensorShe
             CreateEmitterAtBone( self, -1, self.Army, v )
         end
 
+        local detonationHeight = bp.DetonateBelowHeight
         local vx, vy, vz = self:GetVelocity()
-        local velocity = 16
+        -- Normalize our velocity to ogrids/second
+        vx, vy, vz = vx*10, vy*10, vz*10
+        local vMult = bp.InitialSpeed/(10 * self:GetCurrentSpeed())
+
+        -- Time to impact (with our reduced speed) is calculated using the quadratic formula and vMult.
+        local timeToImpact = ((-vy - MathSqrt(MathPow(vy,2) - 2*g*detonationHeight))/g) / vMult
+
+        -- Calculate the new ballistic acceleration
+        local ballisticAcceleration = -2 * (detonationHeight + vy*vMult * timeToImpact) / MathPow(timeToImpact, 2)
+
+        -- Update our velocity values to their new lower values 
+        vx, vy, vz = vx*vMult, vy*vMult, vz*vMult
 
 		-- One initial projectile following same directional path as the original
-        self:CreateChildProjectile(bp.FragmentId):SetVelocity(vx,0.8*vy, vz):SetVelocity(velocity):PassDamageData(self.DamageData)
+        self:CreateChildProjectile(bp.FragmentId)
+            :SetVelocity(vx, vy, vz)
+            :SetBallisticAcceleration(ballisticAcceleration).DamageData = self.DamageData
 
 		-- Create several other projectiles in a dispersal pattern
         local numProjectiles = bp.Fragments - 1
-        local angle = (2 * math.pi) / numProjectiles
+        local angle = (2 * MathPi) / numProjectiles
         local angleInitial = RandomFloat( 0, angle )
 
         -- Randomization of the spread
         local angleVariation = angle * 8 -- Adjusts angle variance spread
-        local spreadMul = 0.8 -- Adjusts the width of the dispersal        
-
-        local xVec = 0 
-        local yVec = vy*0.8
-        local zVec = 0
+        local spreadMagnitude = bp.FragmentRadius / timeToImpact -- Adjusts the width of the dispersal
 
+        local xVec
+        local zVec
+        local offsetAngle
+        local magnitudeVariation
+
         -- Launch projectiles at semi-random angles away from split location
         for i = 0, numProjectiles - 1 do
-            xVec = vx + (math.sin(angleInitial + (i*angle) + RandomFloat(-angleVariation, angleVariation))) * spreadMul
-            zVec = vz + (math.cos(angleInitial + (i*angle) + RandomFloat(-angleVariation, angleVariation))) * spreadMul
-            local proj = self:CreateChildProjectile(bp.FragmentId)
-            proj:SetVelocity(xVec,yVec,zVec)
-            proj:SetVelocity(velocity)
-            proj.DamageData = self.DamageData
+            offsetAngle = angleInitial + (i*angle) + RandomFloat(-angleVariation, angleVariation)
+            magnitudeVariation = RandomFloat(0.9, 1.1)
+            xVec = vx + MathSin(offsetAngle) * spreadMagnitude * magnitudeVariation
+            zVec = vz + MathCos(offsetAngle) * spreadMagnitude * magnitudeVariation
+            self:CreateChildProjectile(bp.FragmentId)
+                :SetVelocity(xVec, vy, zVec)
+                :SetVelocity(bp.InitialSpeed + RandomFloat(-bp.InitialSpeedRange, bp.InitialSpeedRange))
+                :SetBallisticAcceleration(ballisticAcceleration).DamageData = self.DamageData
         end
 
         self:Destroy()

projectiles/AIFFragmentationSensorShell02/AIFFragmentationSensorShell02_proj.bp

@@ -39,15 +39,14 @@ ProjectileBlueprint {
     Physics = {
         DestroyOnWater = true,
         DetonateBelowHeight = 24,
-        InitialSpeed = 14.6,
+        InitialSpeed = 12,
         InitialSpeedRange = 3,
         InitialSpeedReduceDistance = 30,
         LeadTarget = false,
-        MaxZigZag = 0,
         TurnRate = 360,
         VelocityAlign = true,
-        ZigZagFrequency = 0,
         Fragments = 6,
-        FragmentId = '/projectiles/AIFFragmentationSensorShell03/AIFFragmentationSensorShell03_proj.bp'
+        FragmentId = '/projectiles/AIFFragmentationSensorShell03/AIFFragmentationSensorShell03_proj.bp',
+        FragmentRadius = 4,
     },
 }

projectiles/AIFFragmentationSensorShell02/AIFFragmentationSensorShell02_script.lua

@@ -8,6 +8,22 @@ local EffectTemplate = import("/lua/effecttemplates.lua")
 local AArtilleryFragmentationSensorShellProjectile = import("/lua/aeonprojectiles.lua").AArtilleryFragmentationSensorShellProjectile02
 local RandomFloat = import("/lua/utilities.lua").GetRandomFloat
 
+local MathSqrt = math.sqrt
+local MathPow = math.pow
+local MathPi = math.pi
+local MathSin = math.sin
+local MathCos = math.cos
+
+-- We'll update our ballistic parameters so we still hit the target, but only need
+-- to do it once for the subprojectiles, because the velocity delta will be very similar
+-- and these won't change much/at all.
+local ballisticAcceleration
+local vMult
+local spreadMagnitude
+
+-- Gravitational constant
+local g = -4.9
+
 --- Aeon Quantic Cluster Fragmentation Sensor shell script , Child Projectile after 1st split - XAB2307
 ---@class AIFFragmentationSensorShell02 : AArtilleryFragmentationSensorShellProjectile02
 AIFFragmentationSensorShell02 = ClassProjectile(AArtilleryFragmentationSensorShellProjectile) {
@@ -25,35 +41,59 @@ AIFFragmentationSensorShell02 = ClassProjectile(AArtilleryFragmentationSensorShe
 	        end
 
 			local vx, vy, vz = self:GetVelocity()
-	        local velocity = 12
+			-- Normalize our velocity to ogrids/second
+			vx, vy, vz = vx*10, vy*10, vz*10
+
+			-- If we haven't already calculated our ballistic acceleration, do so now
+			-- This shouldn't change much between subprojectiles, so we only need to do it once
+			if not ballisticAcceleration then
+				local detonationHeight = bp.DetonateBelowHeight
+				vMult = bp.InitialSpeed/(10 * self:GetCurrentSpeed())
+
+				-- Time to impact (with our reduced speed) is calculated using the quadratic formula and vMult.
+				local timeToImpact = ((-vy - MathSqrt(MathPow(vy,2) - 2*g*detonationHeight))/g) / vMult
+
+				-- Calculate the new ballistic acceleration
+				ballisticAcceleration = -2 * (detonationHeight + vy*vMult * timeToImpact) / MathPow(timeToImpact, 2)
+				spreadMagnitude = bp.FragmentRadius / timeToImpact
+			end
+
+			-- Update our velocity values
+			-- There appears to be inevitable decay with child projectiles, so we give a slight vertical lift to compensate
+			vx, vy, vz = vx*vMult, vy*vMult + 2, vz*vMult
 
 			-- One initial projectile following same directional path as the original
-            self:CreateChildProjectile(bp.FragmentId):SetVelocity(vx,0.8*vy, vz):SetVelocity(velocity):PassDamageData(self.DamageData)
+			self:CreateChildProjectile(bp.FragmentId)
+				:SetVelocity(vx, vy, vz)
+				:SetVelocity(bp.InitialSpeed)
+				:SetBallisticAcceleration(ballisticAcceleration).DamageData = self.DamageData
 
 			-- Create several other projectiles in a dispersal pattern
             local numProjectiles = bp.Fragments - 1
-            local angle = (2 * math.pi) / numProjectiles
+            local angle = (2 * MathPi) / numProjectiles
             local angleInitial = RandomFloat( 0, angle )
 
             -- Randomization of the spread
             local angleVariation = angle * 13 -- Adjusts angle variance spread
-            local spreadMul = 0.4 -- Adjusts the width of the dispersal        
-	        local xVec = 0 
-	        local yVec = vy*0.8
-	        local zVec = 0
-
-	        -- Launch projectiles at semi-random angles away from split location
-	        for i = 0, numProjectiles - 1 do
-	            xVec = vx + (math.sin(angleInitial + (i*angle) + RandomFloat(-angleVariation, angleVariation))) * spreadMul
-	            zVec = vz + (math.cos(angleInitial + (i*angle) + RandomFloat(-angleVariation, angleVariation))) * spreadMul 
-                local proj = self:CreateChildProjectile(bp.FragmentId)
-	            proj:SetVelocity(xVec,yVec,zVec)
-	            proj:SetVelocity(velocity)
-	            proj.DamageData = self.DamageData
-	        end
+			local xVec
+			local zVec
+			local offsetAngle
+			local magnitudeVariation
+
+			-- Launch projectiles at semi-random angles away from split location
+			for i = 0, numProjectiles - 1 do
+				offsetAngle = angleInitial + (i*angle) + RandomFloat(-angleVariation, angleVariation)
+				magnitudeVariation = RandomFloat(0.9, 1.1)
+				xVec = vx + MathSin(offsetAngle) * spreadMagnitude * magnitudeVariation
+				zVec = vz + MathCos(offsetAngle) * spreadMagnitude * magnitudeVariation
+				self:CreateChildProjectile(bp.FragmentId)
+					:SetVelocity(xVec, vy, zVec)
+					:SetVelocity(bp.InitialSpeed + RandomFloat(-bp.InitialSpeedRange, bp.InitialSpeedRange))
+					:SetBallisticAcceleration(ballisticAcceleration).DamageData = self.DamageData
+			end
 	        self:Destroy()
 		else
-	        self:DoDamage( self, self.DamageData, TargetEntity)
+	        self:DoDamage(self, self.DamageData, TargetEntity)
 	        self:OnImpactDestroy(TargetType, TargetEntity)
         end
     end,