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vcmi/AI/BattleAI/AttackPossibility.cpp
2023-08-26 13:06:51 +03:00

329 lines
10 KiB
C++

/*
* AttackPossibility.cpp, part of VCMI engine
*
* Authors: listed in file AUTHORS in main folder
*
* License: GNU General Public License v2.0 or later
* Full text of license available in license.txt file, in main folder
*
*/
#include "StdInc.h"
#include "AttackPossibility.h"
#include "../../lib/CStack.h" // TODO: remove
// Eventually only IBattleInfoCallback and battle::Unit should be used,
// CUnitState should be private and CStack should be removed completely
uint64_t averageDmg(const DamageRange & range)
{
return (range.min + range.max) / 2;
}
void DamageCache::cacheDamage(const battle::Unit * attacker, const battle::Unit * defender, std::shared_ptr<CBattleInfoCallback> hb)
{
auto damage = averageDmg(hb->battleEstimateDamage(attacker, defender, 0).damage);
damageCache[attacker->unitId()][defender->unitId()] = damage / attacker->getCount();
}
void DamageCache::buildDamageCache(std::shared_ptr<HypotheticBattle> hb, int side)
{
auto stacks = hb->battleGetUnitsIf([=](const battle::Unit * u) -> bool
{
return true;
});
std::vector<const battle::Unit *> ourUnits, enemyUnits;
for(auto stack : stacks)
{
if(stack->unitSide() == side)
ourUnits.push_back(stack);
else
enemyUnits.push_back(stack);
}
for(auto ourUnit : ourUnits)
{
if(!ourUnit->alive())
continue;
for(auto enemyUnit : enemyUnits)
{
if(enemyUnit->alive())
{
cacheDamage(ourUnit, enemyUnit, hb);
cacheDamage(enemyUnit, ourUnit, hb);
}
}
}
}
int64_t DamageCache::getDamage(const battle::Unit * attacker, const battle::Unit * defender, std::shared_ptr<CBattleInfoCallback> hb)
{
auto damage = damageCache[attacker->unitId()][defender->unitId()] * attacker->getCount();
if(damage == 0)
{
cacheDamage(attacker, defender, hb);
damage = damageCache[attacker->unitId()][defender->unitId()] * attacker->getCount();
}
return static_cast<int64_t>(damage);
}
int64_t DamageCache::getOriginalDamage(const battle::Unit * attacker, const battle::Unit * defender, std::shared_ptr<CBattleInfoCallback> hb)
{
if(parent)
{
auto attackerDamageMap = parent->damageCache.find(attacker->unitId());
if(attackerDamageMap != parent->damageCache.end())
{
auto targetDamage = attackerDamageMap->second.find(defender->unitId());
if(targetDamage != attackerDamageMap->second.end())
{
return static_cast<int64_t>(targetDamage->second * attacker->getCount());
}
}
}
return getDamage(attacker, defender, hb);
}
AttackPossibility::AttackPossibility(BattleHex from, BattleHex dest, const BattleAttackInfo & attack)
: from(from), dest(dest), attack(attack)
{
}
int64_t AttackPossibility::damageDiff() const
{
return defenderDamageReduce - attackerDamageReduce - collateralDamageReduce + shootersBlockedDmg;
}
int64_t AttackPossibility::attackValue() const
{
return damageDiff();
}
/// <summary>
/// How enemy damage will be reduced by this attack
/// Half bounty for kill, half for making damage equal to enemy health
/// Bounty - the killed creature average damage calculated against attacker
/// </summary>
int64_t AttackPossibility::calculateDamageReduce(
const battle::Unit * attacker,
const battle::Unit * defender,
uint64_t damageDealt,
DamageCache & damageCache,
std::shared_ptr<CBattleInfoCallback> state)
{
const float HEALTH_BOUNTY = 0.5;
const float KILL_BOUNTY = 1.0 - HEALTH_BOUNTY;
vstd::amin(damageDealt, defender->getAvailableHealth());
// FIXME: provide distance info for Jousting bonus
auto attackerUnitForMeasurement = attacker;
if(!attackerUnitForMeasurement || attackerUnitForMeasurement->isTurret())
{
auto ourUnits = state->battleGetUnitsIf([&](const battle::Unit * u) -> bool
{
return u->unitSide() != defender->unitSide()
&& !u->isTurret()
&& u->creatureId() != CreatureID::CATAPULT
&& u->creatureId() != CreatureID::BALLISTA
&& u->creatureId() != CreatureID::FIRST_AID_TENT
&& u->getCount();
});
if(ourUnits.empty())
attackerUnitForMeasurement = defender;
else
attackerUnitForMeasurement = ourUnits.front();
}
auto enemyDamageBeforeAttack = damageCache.getOriginalDamage(defender, attackerUnitForMeasurement, state);
auto enemiesKilled = damageDealt / defender->getMaxHealth() + (damageDealt % defender->getMaxHealth() >= defender->getFirstHPleft() ? 1 : 0);
auto damagePerEnemy = enemyDamageBeforeAttack / (double)defender->getCount();
return (int64_t)(damagePerEnemy * (enemiesKilled * KILL_BOUNTY + damageDealt * HEALTH_BOUNTY / (double)defender->getMaxHealth()));
}
int64_t AttackPossibility::evaluateBlockedShootersDmg(
const BattleAttackInfo & attackInfo,
BattleHex hex,
DamageCache & damageCache,
std::shared_ptr<CBattleInfoCallback> state)
{
int64_t res = 0;
if(attackInfo.shooting)
return 0;
auto attacker = attackInfo.attacker;
auto hexes = attacker->getSurroundingHexes(hex);
for(BattleHex tile : hexes)
{
auto st = state->battleGetUnitByPos(tile, true);
if(!st || !state->battleMatchOwner(st, attacker))
continue;
if(!state->battleCanShoot(st))
continue;
// FIXME: provide distance info for Jousting bonus
BattleAttackInfo rangeAttackInfo(st, attacker, 0, true);
rangeAttackInfo.defenderPos = hex;
BattleAttackInfo meleeAttackInfo(st, attacker, 0, false);
meleeAttackInfo.defenderPos = hex;
auto rangeDmg = state->battleEstimateDamage(rangeAttackInfo);
auto meleeDmg = state->battleEstimateDamage(meleeAttackInfo);
int64_t gain = averageDmg(rangeDmg.damage) - averageDmg(meleeDmg.damage) + 1;
res += gain;
}
return res;
}
AttackPossibility AttackPossibility::evaluate(
const BattleAttackInfo & attackInfo,
BattleHex hex,
DamageCache & damageCache,
std::shared_ptr<CBattleInfoCallback> state)
{
auto attacker = attackInfo.attacker;
auto defender = attackInfo.defender;
const std::string cachingStringBlocksRetaliation = "type_BLOCKS_RETALIATION";
static const auto selectorBlocksRetaliation = Selector::type()(BonusType::BLOCKS_RETALIATION);
const auto attackerSide = state->playerToSide(state->battleGetOwner(attacker));
const bool counterAttacksBlocked = attacker->hasBonus(selectorBlocksRetaliation, cachingStringBlocksRetaliation);
AttackPossibility bestAp(hex, BattleHex::INVALID, attackInfo);
std::vector<BattleHex> defenderHex;
if(attackInfo.shooting)
defenderHex = defender->getHexes();
else
defenderHex = CStack::meleeAttackHexes(attacker, defender, hex);
for(BattleHex defHex : defenderHex)
{
if(defHex == hex) // should be impossible but check anyway
continue;
AttackPossibility ap(hex, defHex, attackInfo);
ap.attackerState = attacker->acquireState();
ap.shootersBlockedDmg = bestAp.shootersBlockedDmg;
const int totalAttacks = ap.attackerState->getTotalAttacks(attackInfo.shooting);
if (!attackInfo.shooting)
ap.attackerState->setPosition(hex);
std::vector<const battle::Unit*> units;
if (attackInfo.shooting)
units = state->getAttackedBattleUnits(attacker, defHex, true, BattleHex::INVALID);
else
units = state->getAttackedBattleUnits(attacker, defHex, false, hex);
// ensure the defender is also affected
bool addDefender = true;
for(auto unit : units)
{
if (unit->unitId() == defender->unitId())
{
addDefender = false;
break;
}
}
if(addDefender)
units.push_back(defender);
for(auto u : units)
{
if(!ap.attackerState->alive())
break;
auto defenderState = u->acquireState();
ap.affectedUnits.push_back(defenderState);
for(int i = 0; i < totalAttacks; i++)
{
int64_t damageDealt, damageReceived, defenderDamageReduce, attackerDamageReduce;
DamageEstimation retaliation;
auto attackDmg = state->battleEstimateDamage(ap.attack, &retaliation);
vstd::amin(attackDmg.damage.min, defenderState->getAvailableHealth());
vstd::amin(attackDmg.damage.max, defenderState->getAvailableHealth());
vstd::amin(retaliation.damage.min, ap.attackerState->getAvailableHealth());
vstd::amin(retaliation.damage.max, ap.attackerState->getAvailableHealth());
damageDealt = averageDmg(attackDmg.damage);
defenderDamageReduce = calculateDamageReduce(attacker, defender, damageDealt, damageCache, state);
ap.attackerState->afterAttack(attackInfo.shooting, false);
//FIXME: use ranged retaliation
damageReceived = 0;
attackerDamageReduce = 0;
if (!attackInfo.shooting && defenderState->ableToRetaliate() && !counterAttacksBlocked)
{
damageReceived = averageDmg(retaliation.damage);
attackerDamageReduce = calculateDamageReduce(defender, attacker, damageReceived, damageCache, state);
defenderState->afterAttack(attackInfo.shooting, true);
}
bool isEnemy = state->battleMatchOwner(attacker, u);
// this includes enemy units as well as attacker units under enemy's mind control
if(isEnemy)
ap.defenderDamageReduce += defenderDamageReduce;
// damaging attacker's units (even those under enemy's mind control) is considered friendly fire
if(attackerSide == u->unitSide())
ap.collateralDamageReduce += defenderDamageReduce;
if(u->unitId() == defender->unitId() ||
(!attackInfo.shooting && CStack::isMeleeAttackPossible(u, attacker, hex)))
{
//FIXME: handle RANGED_RETALIATION ?
ap.attackerDamageReduce += attackerDamageReduce;
}
ap.attackerState->damage(damageReceived);
defenderState->damage(damageDealt);
if (!ap.attackerState->alive() || !defenderState->alive())
break;
}
}
if(!bestAp.dest.isValid() || ap.attackValue() > bestAp.attackValue())
bestAp = ap;
}
// check how much damage we gain from blocking enemy shooters on this hex
bestAp.shootersBlockedDmg = evaluateBlockedShootersDmg(attackInfo, hex, damageCache, state);
#if BATTLE_TRACE_LEVEL>=1
logAi->trace("BattleAI best AP: %s -> %s at %d from %d, affects %d units: d:%lld a:%lld c:%lld s:%lld",
attackInfo.attacker->unitType()->getJsonKey(),
attackInfo.defender->unitType()->getJsonKey(),
(int)bestAp.dest, (int)bestAp.from, (int)bestAp.affectedUnits.size(),
bestAp.defenderDamageReduce, bestAp.attackerDamageReduce, bestAp.collateralDamageReduce, bestAp.shootersBlockedDmg);
#endif
//TODO other damage related to attack (eg. fire shield and other abilities)
return bestAp;
}