Fix excess projectiles in the same tick impacting entities that die that tick

changelog/snippets/fix.6532.md

@@ -0,0 +1 @@
+- (#6532) Fix excess projectiles impacting entities that die in the same tick. For example, 6 tactical missiles impacting a shield at the same time, despite only 3 being needed to bring down the shield.

lua/shield.lua

@@ -150,6 +150,7 @@ end
 ---@field ImpactMeshBp string
 ---@field SkipAttachmentCheck boolean
 ---@field AbsorptionTypeDamageTypeToMulti table<DamageType, number>
+---@field DisallowCollisions boolean
 Shield = ClassShield(moho.shield_methods, Entity) {
 
     RemainEnabledWhenAttached = false,
@@ -187,6 +188,7 @@ Shield = ClassShield(moho.shield_methods, Entity) {
         self.PassOverkillDamage = spec.PassOverkillDamage
         self.ImpactMeshBp = spec.ImpactMesh
         self.SkipAttachmentCheck = spec.SkipAttachmentCheck
+        self.DisallowCollisions = false
 
         if spec.ImpactEffects ~= '' then
             self.ImpactEffects = EffectTemplate[spec.ImpactEffects]
@@ -340,6 +342,7 @@ Shield = ClassShield(moho.shield_methods, Entity) {
 
         -- change state if we're enabled
         if self.Enabled then
+            self.DisallowCollisions = true
             ChangeState(self, self.EnergyDrainedState)
         end
     end,
@@ -350,6 +353,7 @@ Shield = ClassShield(moho.shield_methods, Entity) {
 
         -- change state if we're enabled
         if self.Enabled then
+            self.DisallowCollisions = false
             ChangeState(self, self.OnState)
         end
     end,
@@ -576,6 +580,7 @@ Shield = ClassShield(moho.shield_methods, Entity) {
 
             -- if we have no health, collapse
             if EntityGetHealth(self) <= 0 then
+                self.DisallowCollisions = true
                 ChangeState(self, self.DamageDrainedState)
                 -- otherwise, attempt to regenerate
             else
@@ -682,6 +687,10 @@ Shield = ClassShield(moho.shield_methods, Entity) {
     -- @param other The projectile we're checking the collision with
     OnCollisionCheck = function(self, other)
 
+        if self.DisallowCollisions then
+            return false
+        end
+
         -- special logic when it is a projectile to simulate air crashes
         if other.CrashingAirplaneShieldCollisionLogic then
             if other.ShieldImpacted then
@@ -723,6 +732,10 @@ Shield = ClassShield(moho.shield_methods, Entity) {
     -- @param firingWeapon The weapon the beam originates from that we're checking the collision with
     OnCollisionCheckWeapon = function(self, firingWeapon)
 
+        if self.DisallowCollisions then
+            return false
+        end
+
         -- if we're allied, check if we allow that type of collision
         if self.Army == firingWeapon.Army or IsAlly(self.Army, firingWeapon.Army) then
             return firingWeapon.Blueprint.CollideFriendly
@@ -917,6 +930,7 @@ Shield = ClassShield(moho.shield_methods, Entity) {
             self.RegenThreadStartTick = GetGameTick() + 10 * self.RegenStartTime
 
             -- back to the regular onstate
+            self.DisallowCollisions = false
             ChangeState(self, self.OnState)
         end,
 

lua/sim/Projectile.lua

@@ -319,9 +319,15 @@ Projectile = ClassProjectile(ProjectileMethods, DebugProjectileComponent) {
 
     --- Called by the engine when the projectile impacts something
     ---@param self Projectile
-    ---@param targetType string
+    ---@param targetType ImpactType
     ---@param targetEntity Unit | Prop
     OnImpact = function(self, targetType, targetEntity)
+        -- Since collision is checked before impacts are run, collision changes caused by impacts need to be checked by impacts
+        -- For example, a shield will first tell every projectile that it can collide with it, and then only afterwards will
+        -- HP be drained from the shield, and collisions turned off due to the shield being down. The same applies for units.
+        if targetEntity.DisallowCollisions then
+            return
+        end
 
         -- localize information for performance
         local position = self:GetPosition()