Fix beyond-all-reason#817, add Spring.SetUnitShieldRechargeDelay

doc/changelog.txt

@@ -25,6 +25,11 @@ Lua:
  - add `Spring.SelectUnit(unitID, bool append = false) -> nil`, single-unit
    version of SelectUnit{Array,Map} that doesn't require a table
  - add `Spring.DeselectUnit(unitID) -> nil`, deselects a unit
+ - add `Spring.SetUnitShieldRechargeDelay(unitID, [weaponNum], [seconds]) -> nil`. Resets a unit's
+   shield regeneration delay. The weapon number is optional if the unit has a single shield. The
+   timer value is also optional, if you leave it nil it will emulate a weapon hit. Note that a
+   weapon hit (both via nil here, and "real" hits) will never decrease the remaining timer, though
+   it can increase it. An explicit numerical value always sets the timer to that many seconds.
  - add `wupget:Unit{Entered,Left}Underwater(unitID, unitDefID, teamID)`. Works very similar
    to the existing Water callins, but EnteredWater applies when the unit dips its toes in water
    while EnteredUnderwater applies when the unit is completely submerged.

rts/Lua/LuaSyncedCtrl.cpp

@@ -190,6 +190,7 @@ bool LuaSyncedCtrl::PushEntries(lua_State* L)
 	REGISTER_LUA_CFUNC(SetUnitBlocking);
 	REGISTER_LUA_CFUNC(SetUnitCrashing);
 	REGISTER_LUA_CFUNC(SetUnitShieldState);
+	REGISTER_LUA_CFUNC(SetUnitShieldRechargeDelay);
 	REGISTER_LUA_CFUNC(SetUnitFlanking);
 	REGISTER_LUA_CFUNC(SetUnitTravel);
 	REGISTER_LUA_CFUNC(SetUnitFuel);
@@ -2925,6 +2926,42 @@ int LuaSyncedCtrl::SetUnitShieldState(lua_State* L)
 	return 0;
 }
 
+/***
+ * @function Spring.SetUnitShieldRechargeDelay
+ * @number unitID
+ * @number[opt] weaponID (optional if the unit only has one shield)
+ * @number[opt] rechargeTime (in seconds; emulates a regular hit if nil)
+ * @treturn nil
+ */
+int LuaSyncedCtrl::SetUnitShieldRechargeDelay(lua_State* L)
+{
+	const auto unit = ParseUnit(L, __func__, 1);
+	if (unit == nullptr)
+		return 0;
+
+	auto shield = static_cast <CPlasmaRepulser*> (unit->shieldWeapon);
+	if (lua_isnumber(L, 2)) {
+		const size_t index = lua_tointeger(L, 2) - LUA_WEAPON_BASE_INDEX;
+		if (index < unit->weapons.size())
+			shield = dynamic_cast <CPlasmaRepulser*> (unit->weapons[index]);
+	}
+	if (shield == nullptr)
+		return 0;
+
+	if (lua_isnumber(L, 3)) {
+		const auto seconds = lua_tofloat(L, 3);
+		const auto frames = static_cast <int> (seconds * GAME_SPEED);
+		shield->SetRechargeDelay(frames, true);
+	} else {
+		/* Note, overwrite set to false on purpose. This is to emulate a regular
+		 * weapon hit. This lets a sophisticated shield handler gadget coexist
+		 * with a basic "emulate hits" gadget without the latter having to care.
+		 * You can put the weaponDef value explicitly if you want to overwrite. */
+		shield->SetRechargeDelay(shield->weaponDef->shieldRechargeDelay, false);
+	}
+
+	return 0;
+}
 
 /***
  * @function Spring.SetUnitFlanking

rts/Lua/LuaSyncedCtrl.h

@@ -99,6 +99,7 @@ class LuaSyncedCtrl
 		static int SetUnitBlocking(lua_State* L);
 		static int SetUnitCrashing(lua_State* L);
 		static int SetUnitShieldState(lua_State* L);
+		static int SetUnitShieldRechargeDelay(lua_State* L);
 		static int SetUnitFlanking(lua_State* L);
 		static int SetUnitTravel(lua_State* L);
 		static int SetUnitFuel(lua_State* L);

rts/Sim/Weapons/PlasmaRepulser.cpp

@@ -165,11 +165,18 @@ void CPlasmaRepulser::Update()
 	sscPool.UpdateCollection(this);
 }
 
+void CPlasmaRepulser::SetRechargeDelay(int delay, bool overwrite)
+{
+	if (overwrite)
+		rechargeDelay = delay;
+	else
+		rechargeDelay = std::max(rechargeDelay, delay);
+}
+
 // Returns true if the projectile is destroyed.
 bool CPlasmaRepulser::IncomingProjectile(CWeaponProjectile* p, const float3& hitPos)
 {
 	const int defHitFrames = weaponDef->visibleShieldHitFrames;
-	const int defRechargeDelay = weaponDef->shieldRechargeDelay;
 
 	// gadget handles the collision event, don't touch the projectile
 	// start-pos only makes sense for beams, pass current p->pos here
@@ -187,7 +194,7 @@ bool CPlasmaRepulser::IncomingProjectile(CWeaponProjectile* p, const float3& hit
 	if (teamHandler.Team(owner->team)->res.energy < weaponDef->shieldEnergyUse)
 		return false;
 
-	rechargeDelay = defRechargeDelay;
+	SetRechargeDelay(weaponDef->shieldRechargeDelay, false);
 
 	if (weaponDef->shieldRepulser) {
 		// bounce the projectile

rts/Sim/Weapons/PlasmaRepulser.h

@@ -25,6 +25,7 @@ class CPlasmaRepulser: public CWeapon
 
 
 	void SetEnabled(bool b) { isEnabled = b; }
+	void SetRechargeDelay(int delay, bool overwrite);
 	void SetCurPower(float p) { curPower = p; }
 
 	bool IsEnabled() const { return isEnabled; }