Warhead activation target health thresholds (#1398)

### Customizable Warhead trigger conditions

- It is now possible to make warheads only trigger when target's HP is
above and/or below certain percentage.
- Both conditions need to evaluate to true in order for the warhead to
trigger.

In `rulesmd.ini`:
```ini
[SOMEWARHEAD]               ; WarheadType
AffectsAbovePercent=0.0     ; floating point value, percents or absolute
AffectsBelowPercent=1.0     ; floating point value, percents or absolute
```

---------

Co-authored-by: FS-21 <[email protected]>

Author: Metadorius

CREDITS.md

@@ -48,6 +48,7 @@ This page lists all the individual contributions to the project by their author.
   - Ability to disable shadow for debris & meteor animations
   - Voxel light source position customization
   - `UseFixedVoxelLighting`
+  - Warhead activation target health thresholds
 - **Uranusian (Thrifinesma)**:
   - Mind Control enhancement
   - Custom warhead splash list
@@ -144,6 +145,7 @@ This page lists all the individual contributions to the project by their author.
   - Map Events 604 & 605 for checking if a specific Techno enters in a cell
   - Warhead that can not kill
   - `Pips.HideIfNoStrength` and `SelfHealing.EnabledBy` additions for shields
+  - Warhead activation target health thresholds enhancements
 - **Starkku**:
   - Misc. minor bugfixes & improvements
   - AI script actions:

docs/Fixed-or-Improved-Logics.md

@@ -1846,6 +1846,20 @@ Rocker.AmplitudeMultiplier=1.0  ; floating point value, multiplier
 Rocker.AmplitudeOverride=       ; integer
 ```
 
+### Customizable Warhead trigger conditions
+
+- It is now possible to make warheads only trigger when target's HP is above and/or below certain percentage.
+  - Both conditions need to evaluate to true in order for the warhead to trigger.
+- If set to `false`, `EffectsRequireVerses` makes the Phobos-introduced warhead effects trigger even if it can't damage the target because of it's current ArmorType (e.g. 0% in `Verses`).
+
+In `rulesmd.ini`:
+```ini
+[SOMEWARHEAD]               ; WarheadType
+AffectsAbovePercent=0.0     ; floating point value, percents or absolute
+AffectsBelowPercent=1.0     ; floating point value, percents or absolute
+EffectsRequireVerses=false  ; boolean
+```
+
 ### Customizable Warhead animation behaviour
 
 - It is possible to make game play random animation from `AnimList` by setting `AnimList.PickRandom` to true. The result is similar to what `EMEffect=true` produces, however it comes with no side-effects (`EMEffect=true` prevents `Inviso=true` projectiles from snapping on targets, making them miss moving targets).

docs/New-or-Enhanced-Logics.md

@@ -1877,7 +1877,7 @@ FireUp.ResetInRetarget=true     ; boolean
 All new Warhead effects
 - Can be used with `CellSpread` and Ares' GenericWarhead superweapon where applicable.
 - Cannot be used with `MindControl.Permanent=yes` of Ares.
-- Respect `Verses` where applicable unless `EffectsRequireVerses` is set to false. If target has an active shield, its armor type is used instead unless warhead can penetrate the shield.
+- Respect `Verses` where applicable unless `EffectsRequireVerses` is set to `false`. If target has an active shield, its armor type is used instead unless warhead can penetrate the shield.
 ```
 
 ### Break Mind Control on impact

docs/Whats-New.md

@@ -599,6 +599,7 @@ New:
 - Draw visual effects for airburst weapons (by CrimRecya)
 - Unit `Speed` setting now accepts floating point values (by Starkku)
 - `Strafing` is now disabled by default when using `Trajectory` (by CrimRecya)
+- Warhead activation target health thresholds (by FS-21, Kerbiter)
 
 Vanilla fixes:
 - Allow AI to repair structures built from base nodes/trigger action 125/SW delivery in single player missions (by Trsdy)

src/Ext/Bullet/Hooks.DetonateLogics.cpp

@@ -11,17 +11,27 @@
 #include <AircraftClass.h>
 #include <TacticalClass.h>
 
-DEFINE_HOOK(0x4690D4, BulletClass_Logics_ScreenShake, 0x6)
+DEFINE_HOOK(0x4690D4, BulletClass_Logics_NewChecks, 0x6)
 {
-	enum { SkipShaking = 0x469130 };
+	enum { SkipShaking = 0x469130, GoToExtras = 0x469AA4 };
 
+	GET(BulletClass*, pBullet, ESI);
 	GET(WarheadTypeClass*, pWarhead, EAX);
 	GET_BASE(CoordStruct*, pCoords, 0x8);
 
-	auto const pWHExt = WarheadTypeExt::ExtMap.Find(pWarhead);
+	auto const pExt = WarheadTypeExt::ExtMap.Find(pWarhead);
+
+	if (auto pTarget = abstract_cast<TechnoClass*>(pBullet->Target))
+	{
+		// Check if the WH should affect the techno target or skip it
+		if (!pExt->IsHealthInThreshold(pTarget) && pBullet->Owner != pBullet->Target)
+			return GoToExtras;
+	}
+
+	// Check for ScreenShake
 	auto&& [_, visible] = TacticalClass::Instance->CoordsToClient(*pCoords);
 
-	if (pWHExt->ShakeIsLocal && !visible)
+	if (pExt->ShakeIsLocal && !visible)
 		return SkipShaking;
 
 	return 0;
@@ -312,6 +322,13 @@ DEFINE_HOOK(0x469AA4, BulletClass_Logics_Extras, 0x5)
 			auto const pWH = pWeaponExt->ExtraWarheads[i];
 			int damage = defaultDamage;
 			size_t size = pWeaponExt->ExtraWarheads_DamageOverrides.size();
+			auto const pWHExt = WarheadTypeExt::ExtMap.Find(pWH);
+
+			if (auto const pTarget = abstract_cast<TechnoClass*>(pThis->Target))
+			{
+				if (!pWHExt->IsHealthInThreshold(pTarget))
+					continue;
+			}
 
 			if (size > i)
 				damage = pWeaponExt->ExtraWarheads_DamageOverrides[i];

src/Ext/RadSite/Body.cpp

@@ -16,6 +16,10 @@ void RadSiteExt::ExtData::Initialize()
 bool RadSiteExt::ExtData::ApplyRadiationDamage(TechnoClass* pTarget, int& damage)
 {
 	const auto pWarhead = this->Type->GetWarhead();
+	const auto pWHExt = WarheadTypeExt::ExtMap.Find(pWarhead);
+
+	if (!pWHExt->IsHealthInThreshold(pTarget))
+		return false;
 
 	if (!this->Type->GetWarheadDetonate())
 	{
@@ -25,14 +29,9 @@ bool RadSiteExt::ExtData::ApplyRadiationDamage(TechnoClass* pTarget, int& damage
 	else
 	{
 		if (this->Type->GetWarheadDetonateFull())
-		{
 			WarheadTypeExt::DetonateAt(pWarhead, pTarget, this->RadInvoker, damage, this->RadHouse);
-		}
 		else
-		{
-			const auto pWHExt = WarheadTypeExt::ExtMap.Find(pWarhead);
 			pWHExt->DamageAreaWithTarget(pTarget->GetCoords(), damage, this->RadInvoker, pWarhead, true, this->RadHouse, pTarget);
-		}
 
 		if (!pTarget->IsAlive)
 			return false;

src/Ext/WarheadType/Body.cpp

@@ -35,12 +35,25 @@ bool WarheadTypeExt::ExtData::CanAffectTarget(TechnoClass* pTarget) const
 	if (!pTarget)
 		return false;
 
+	if (!IsHealthInThreshold(pTarget))
+		return false;
+
 	if (!this->EffectsRequireVerses)
 		return true;
 
 	return GeneralUtils::GetWarheadVersusArmor(this->OwnerObject(), pTarget) != 0.0;
 }
 
+bool WarheadTypeExt::ExtData::IsHealthInThreshold(TechnoClass* pTarget) const
+{
+	// Check if the WH should affect the techno target or skip it
+	double hp = pTarget->GetHealthPercentage();
+	bool hpBelowPercent = hp <= this->AffectsBelowPercent;
+	bool hpAbovePercent = hp > this->AffectsAbovePercent;
+
+	return hpBelowPercent && hpAbovePercent;
+}
+
 // Checks if Warhead can affect target that might or might be currently invulnerable.
 bool WarheadTypeExt::ExtData::CanAffectInvulnerable(TechnoClass* pTarget) const
 {
@@ -274,6 +287,12 @@ void WarheadTypeExt::ExtData::LoadFromINIFile(CCINIClass* const pINI)
 
 	this->AirstrikeTargets.Read(exINI, pSection, "AirstrikeTargets");
 
+	this->AffectsAbovePercent.Read(exINI, pSection, "AffectsAbovePercent");
+	this->AffectsBelowPercent.Read(exINI, pSection, "AffectsBelowPercent");
+
+	if (this->AffectsAbovePercent > this->AffectsBelowPercent)
+		Debug::Log("[Developer warning][%s] AffectsAbovePercent is bigger than AffectsBelowPercent, the warhead will never activate!\n", pSection);
+
 	// Convert.From & Convert.To
 	TypeConvertGroup::Parse(this->Convert_Pairs, exINI, pSection, AffectedHouse::All);
 
@@ -493,6 +512,9 @@ void WarheadTypeExt::ExtData::Serialize(T& Stm)
 		.Process(this->SuppressReflectDamage_Types)
 		.Process(this->SuppressReflectDamage_Groups)
 
+		.Process(this->AffectsAbovePercent)
+		.Process(this->AffectsBelowPercent)
+
 		.Process(this->InflictLocomotor)
 		.Process(this->RemoveInflictedLocomotor)
 

src/Ext/WarheadType/Body.h

@@ -177,6 +177,9 @@ class WarheadTypeExt
 
 		Valueable<AffectedTarget> AirstrikeTargets;
 
+		Valueable<double> AffectsAbovePercent;
+		Valueable<double> AffectsBelowPercent;
+
 		// Ares tags
 		// http://ares-developers.github.io/Ares-docs/new/warheads/general.html
 		Valueable<bool> AffectsEnemies;
@@ -352,6 +355,9 @@ class WarheadTypeExt
 
 			, AirstrikeTargets { AffectedTarget::Building }
 
+			, AffectsAbovePercent { 0.0 }
+			, AffectsBelowPercent { 1.0 }
+
 			, AffectsEnemies { true }
 			, AffectsOwner {}
 			, EffectsRequireVerses { true }
@@ -386,6 +392,7 @@ class WarheadTypeExt
 		bool CanAffectTarget(TechnoClass* pTarget) const;
 		bool CanAffectInvulnerable(TechnoClass* pTarget) const;
 		bool EligibleForFullMapDetonation(TechnoClass* pTechno, HouseClass* pOwner) const;
+		bool IsHealthInThreshold(TechnoClass* pTarget) const;
 
 		virtual ~ExtData() = default;
 		virtual void LoadFromINIFile(CCINIClass* pINI) override;