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openmw-tes3mp/apps/openmw/mwmechanics/aicombat.cpp
scrawl c50b18b3bb
Move PathgridGraph out of CellStore
By definition this is not 'Mutable state of a cell' and does not belong in CellStore.

This change should improve startup times (graph is now loaded on demand) and edits to 'pathgrid.hpp' no longer cause the entirety of OpenMW to be rebuilt.
2017-11-27 21:20:31 +00:00

730 lines
28 KiB
C++

#include "aicombat.hpp"
#include <components/misc/rng.hpp>
#include <components/esm/aisequence.hpp>
#include "../mwworld/class.hpp"
#include "../mwworld/esmstore.hpp"
#include "../mwbase/environment.hpp"
#include "../mwbase/dialoguemanager.hpp"
#include "../mwbase/mechanicsmanager.hpp"
#include "../mwrender/animation.hpp"
#include "pathgrid.hpp"
#include "creaturestats.hpp"
#include "steering.hpp"
#include "movement.hpp"
#include "character.hpp"
#include "aicombataction.hpp"
#include "combat.hpp"
#include "coordinateconverter.hpp"
#include "actorutil.hpp"
namespace
{
//chooses an attack depending on probability to avoid uniformity
std::string chooseBestAttack(const ESM::Weapon* weapon);
osg::Vec3f AimDirToMovingTarget(const MWWorld::Ptr& actor, const MWWorld::Ptr& target, const osg::Vec3f& vLastTargetPos,
float duration, int weapType, float strength);
}
namespace MWMechanics
{
/// \brief This class holds the variables AiCombat needs which are deleted if the package becomes inactive.
struct AiCombatStorage : AiTemporaryBase
{
float mAttackCooldown;
float mTimerReact;
float mTimerCombatMove;
bool mReadyToAttack;
bool mAttack;
float mAttackRange;
bool mCombatMove;
osg::Vec3f mLastTargetPos;
const MWWorld::CellStore* mCell;
std::shared_ptr<Action> mCurrentAction;
float mActionCooldown;
float mStrength;
bool mForceNoShortcut;
ESM::Position mShortcutFailPos;
MWMechanics::Movement mMovement;
enum FleeState
{
FleeState_None,
FleeState_Idle,
FleeState_RunBlindly,
FleeState_RunToDestination
};
FleeState mFleeState;
bool mLOS;
float mUpdateLOSTimer;
float mFleeBlindRunTimer;
ESM::Pathgrid::Point mFleeDest;
AiCombatStorage():
mAttackCooldown(0.0f),
mTimerReact(AI_REACTION_TIME),
mTimerCombatMove(0.0f),
mReadyToAttack(false),
mAttack(false),
mAttackRange(0.0f),
mCombatMove(false),
mLastTargetPos(0,0,0),
mCell(NULL),
mCurrentAction(),
mActionCooldown(0.0f),
mStrength(),
mForceNoShortcut(false),
mShortcutFailPos(),
mMovement(),
mFleeState(FleeState_None),
mLOS(false),
mUpdateLOSTimer(0.0f),
mFleeBlindRunTimer(0.0f)
{}
void startCombatMove(bool isDistantCombat, float distToTarget, float rangeAttack, const MWWorld::Ptr& actor, const MWWorld::Ptr& target);
void updateCombatMove(float duration);
void stopCombatMove();
void startAttackIfReady(const MWWorld::Ptr& actor, CharacterController& characterController,
const ESM::Weapon* weapon, bool distantCombat);
void updateAttack(CharacterController& characterController);
void stopAttack();
void startFleeing();
void stopFleeing();
bool isFleeing();
};
AiCombat::AiCombat(const MWWorld::Ptr& actor) :
mTargetActorId(actor.getClass().getCreatureStats(actor).getActorId())
{}
AiCombat::AiCombat(const ESM::AiSequence::AiCombat *combat)
{
mTargetActorId = combat->mTargetActorId;
}
void AiCombat::init()
{
}
/*
* Current AiCombat movement states (as of 0.29.0), ignoring the details of the
* attack states such as CombatMove, Strike and ReadyToAttack:
*
* +----(within strike range)----->attack--(beyond strike range)-->follow
* | | ^ | |
* | | | | |
* pursue<---(beyond follow range)-----+ +----(within strike range)---+ |
* ^ |
* | |
* +-------------------------(beyond follow range)--------------------+
*
*
* Below diagram is high level only, the code detail is a little different
* (but including those detail will just complicate the diagram w/o adding much)
*
* +----------(same)-------------->attack---------(same)---------->follow
* | |^^ |||
* | ||| |||
* | +--(same)-----------------+|+----------(same)------------+||
* | | | ||
* | | | (in range) ||
* | <---+ (too far) | ||
* pursue<-------------------------[door open]<-----+ ||
* ^^^ | ||
* ||| | ||
* ||+----------evade-----+ | ||
* || | [closed door] | ||
* |+----> maybe stuck, check --------------> back up, check door ||
* | ^ | ^ | ^ ||
* | | | | | | ||
* | | +---+ +---+ ||
* | +-------------------------------------------------------+|
* | |
* +---------------------------(same)---------------------------------+
*
* FIXME:
*
* The new scheme is way too complicated, should really be implemented as a
* proper state machine.
*
* TODO:
*
* Use the observer pattern to coordinate attacks, provide intelligence on
* whether the target was hit, etc.
*/
bool AiCombat::execute (const MWWorld::Ptr& actor, CharacterController& characterController, AiState& state, float duration)
{
// get or create temporary storage
AiCombatStorage& storage = state.get<AiCombatStorage>();
//General description
if (actor.getClass().getCreatureStats(actor).isDead())
return true;
MWWorld::Ptr target = MWBase::Environment::get().getWorld()->searchPtrViaActorId(mTargetActorId);
if (target.isEmpty())
return false;
if(!target.getRefData().getCount() || !target.getRefData().isEnabled() // Really we should be checking whether the target is currently registered
// with the MechanicsManager
|| target.getClass().getCreatureStats(target).isDead())
return true;
if (!storage.isFleeing())
{
if (storage.mCurrentAction.get()) // need to wait to init action with its attack range
{
//Update every frame. UpdateLOS uses a timer, so the LOS check does not happen every frame.
updateLOS(actor, target, duration, storage);
float targetReachedTolerance = 0.0f;
if (storage.mLOS)
targetReachedTolerance = storage.mAttackRange;
bool is_target_reached = pathTo(actor, target.getRefData().getPosition().pos, duration, targetReachedTolerance);
if (is_target_reached) storage.mReadyToAttack = true;
}
storage.updateCombatMove(duration);
if (storage.mReadyToAttack) updateActorsMovement(actor, duration, storage);
storage.updateAttack(characterController);
}
else
{
updateFleeing(actor, target, duration, storage);
}
storage.mActionCooldown -= duration;
float& timerReact = storage.mTimerReact;
if (timerReact < AI_REACTION_TIME)
{
timerReact += duration;
}
else
{
timerReact = 0;
if (attack(actor, target, storage, characterController))
return true;
}
return false;
}
bool AiCombat::attack(const MWWorld::Ptr& actor, const MWWorld::Ptr& target, AiCombatStorage& storage, CharacterController& characterController)
{
const MWWorld::CellStore*& currentCell = storage.mCell;
bool cellChange = currentCell && (actor.getCell() != currentCell);
if(!currentCell || cellChange)
{
currentCell = actor.getCell();
}
bool forceFlee = false;
if (!canFight(actor, target))
{
storage.stopAttack();
characterController.setAttackingOrSpell(false);
storage.mActionCooldown = 0.f;
// Continue combat if target is player or player follower/escorter and an attack has been attempted
const std::list<MWWorld::Ptr>& playerFollowersAndEscorters = MWBase::Environment::get().getMechanicsManager()->getActorsSidingWith(MWMechanics::getPlayer());
bool targetSidesWithPlayer = (std::find(playerFollowersAndEscorters.begin(), playerFollowersAndEscorters.end(), target) != playerFollowersAndEscorters.end());
if ((target == MWMechanics::getPlayer() || targetSidesWithPlayer)
&& ((actor.getClass().getCreatureStats(actor).getHitAttemptActorId() == target.getClass().getCreatureStats(target).getActorId())
|| (target.getClass().getCreatureStats(target).getHitAttemptActorId() == actor.getClass().getCreatureStats(actor).getActorId())))
forceFlee = true;
else // Otherwise end combat
return true;
}
const MWWorld::Class& actorClass = actor.getClass();
actorClass.getCreatureStats(actor).setMovementFlag(CreatureStats::Flag_Run, true);
float& actionCooldown = storage.mActionCooldown;
std::shared_ptr<Action>& currentAction = storage.mCurrentAction;
if (!forceFlee)
{
if (actionCooldown > 0)
return false;
if (characterController.readyToPrepareAttack())
{
currentAction = prepareNextAction(actor, target);
actionCooldown = currentAction->getActionCooldown();
}
}
else
{
currentAction.reset(new ActionFlee());
actionCooldown = currentAction->getActionCooldown();
}
if (!currentAction)
return false;
if (storage.isFleeing() != currentAction->isFleeing())
{
if (currentAction->isFleeing())
{
storage.startFleeing();
MWBase::Environment::get().getDialogueManager()->say(actor, "flee");
return false;
}
else
storage.stopFleeing();
}
bool isRangedCombat = false;
float &rangeAttack = storage.mAttackRange;
rangeAttack = currentAction->getCombatRange(isRangedCombat);
// Get weapon characteristics
const ESM::Weapon* weapon = currentAction->getWeapon();
ESM::Position pos = actor.getRefData().getPosition();
osg::Vec3f vActorPos(pos.asVec3());
osg::Vec3f vTargetPos(target.getRefData().getPosition().asVec3());
osg::Vec3f vAimDir = MWBase::Environment::get().getWorld()->aimToTarget(actor, target);
float distToTarget = MWBase::Environment::get().getWorld()->getHitDistance(actor, target);
storage.mReadyToAttack = (currentAction->isAttackingOrSpell() && distToTarget <= rangeAttack && storage.mLOS);
if (storage.mReadyToAttack)
{
storage.startCombatMove(isRangedCombat, distToTarget, rangeAttack, actor, target);
// start new attack
storage.startAttackIfReady(actor, characterController, weapon, isRangedCombat);
if (isRangedCombat)
{
// rotate actor taking into account target movement direction and projectile speed
osg::Vec3f& lastTargetPos = storage.mLastTargetPos;
vAimDir = AimDirToMovingTarget(actor, target, lastTargetPos, AI_REACTION_TIME, (weapon ? weapon->mData.mType : 0), storage.mStrength);
lastTargetPos = vTargetPos;
storage.mMovement.mRotation[0] = getXAngleToDir(vAimDir);
storage.mMovement.mRotation[2] = getZAngleToDir(vAimDir);
}
else
{
storage.mMovement.mRotation[0] = getXAngleToDir(vAimDir);
storage.mMovement.mRotation[2] = getZAngleToDir((vTargetPos-vActorPos)); // using vAimDir results in spastic movements since the head is animated
}
}
return false;
}
void MWMechanics::AiCombat::updateLOS(const MWWorld::Ptr& actor, const MWWorld::Ptr& target, float duration, MWMechanics::AiCombatStorage& storage)
{
static const float LOS_UPDATE_DURATION = 0.5f;
if (storage.mUpdateLOSTimer <= 0.f)
{
storage.mLOS = MWBase::Environment::get().getWorld()->getLOS(actor, target);
storage.mUpdateLOSTimer = LOS_UPDATE_DURATION;
}
else
storage.mUpdateLOSTimer -= duration;
}
void MWMechanics::AiCombat::updateFleeing(const MWWorld::Ptr& actor, const MWWorld::Ptr& target, float duration, MWMechanics::AiCombatStorage& storage)
{
static const float BLIND_RUN_DURATION = 1.0f;
updateLOS(actor, target, duration, storage);
AiCombatStorage::FleeState& state = storage.mFleeState;
switch (state)
{
case AiCombatStorage::FleeState_None:
return;
case AiCombatStorage::FleeState_Idle:
{
float triggerDist = getMaxAttackDistance(target);
if (storage.mLOS &&
(triggerDist >= 1000 || getDistanceMinusHalfExtents(actor, target) <= triggerDist))
{
const ESM::Pathgrid* pathgrid =
MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*storage.mCell->getCell());
bool runFallback = true;
if (pathgrid && !actor.getClass().isPureWaterCreature(actor))
{
ESM::Pathgrid::PointList points;
CoordinateConverter coords(storage.mCell->getCell());
osg::Vec3f localPos = actor.getRefData().getPosition().asVec3();
coords.toLocal(localPos);
int closestPointIndex = PathFinder::GetClosestPoint(pathgrid, localPos);
for (int i = 0; i < static_cast<int>(pathgrid->mPoints.size()); i++)
{
if (i != closestPointIndex && getPathGridGraph(storage.mCell).isPointConnected(closestPointIndex, i))
{
points.push_back(pathgrid->mPoints[static_cast<size_t>(i)]);
}
}
if (!points.empty())
{
ESM::Pathgrid::Point dest = points[Misc::Rng::rollDice(points.size())];
coords.toWorld(dest);
state = AiCombatStorage::FleeState_RunToDestination;
storage.mFleeDest = ESM::Pathgrid::Point(dest.mX, dest.mY, dest.mZ);
runFallback = false;
}
}
if (runFallback)
{
state = AiCombatStorage::FleeState_RunBlindly;
storage.mFleeBlindRunTimer = 0.0f;
}
}
}
break;
case AiCombatStorage::FleeState_RunBlindly:
{
// timer to prevent twitchy movement that can be observed in vanilla MW
if (storage.mFleeBlindRunTimer < BLIND_RUN_DURATION)
{
storage.mFleeBlindRunTimer += duration;
storage.mMovement.mRotation[2] = osg::PI + getZAngleToDir(target.getRefData().getPosition().asVec3()-actor.getRefData().getPosition().asVec3());
storage.mMovement.mPosition[1] = 1;
updateActorsMovement(actor, duration, storage);
}
else
state = AiCombatStorage::FleeState_Idle;
}
break;
case AiCombatStorage::FleeState_RunToDestination:
{
static const float fFleeDistance = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fFleeDistance")->getFloat();
float dist = (actor.getRefData().getPosition().asVec3() - target.getRefData().getPosition().asVec3()).length();
if ((dist > fFleeDistance && !storage.mLOS)
|| pathTo(actor, storage.mFleeDest, duration))
{
state = AiCombatStorage::FleeState_Idle;
}
}
break;
};
}
void AiCombat::updateActorsMovement(const MWWorld::Ptr& actor, float duration, AiCombatStorage& storage)
{
// apply combat movement
MWMechanics::Movement& actorMovementSettings = actor.getClass().getMovementSettings(actor);
actorMovementSettings.mPosition[0] = storage.mMovement.mPosition[0];
actorMovementSettings.mPosition[1] = storage.mMovement.mPosition[1];
actorMovementSettings.mPosition[2] = storage.mMovement.mPosition[2];
rotateActorOnAxis(actor, 2, actorMovementSettings, storage.mMovement);
rotateActorOnAxis(actor, 0, actorMovementSettings, storage.mMovement);
}
void AiCombat::rotateActorOnAxis(const MWWorld::Ptr& actor, int axis,
MWMechanics::Movement& actorMovementSettings, MWMechanics::Movement& desiredMovement)
{
actorMovementSettings.mRotation[axis] = 0;
float& targetAngleRadians = desiredMovement.mRotation[axis];
if (targetAngleRadians != 0)
{
if (smoothTurn(actor, targetAngleRadians, axis))
{
// actor now facing desired direction, no need to turn any more
targetAngleRadians = 0;
}
}
}
int AiCombat::getTypeId() const
{
return TypeIdCombat;
}
unsigned int AiCombat::getPriority() const
{
return 1;
}
MWWorld::Ptr AiCombat::getTarget() const
{
return MWBase::Environment::get().getWorld()->searchPtrViaActorId(mTargetActorId);
}
AiCombat *MWMechanics::AiCombat::clone() const
{
return new AiCombat(*this);
}
void AiCombat::writeState(ESM::AiSequence::AiSequence &sequence) const
{
std::unique_ptr<ESM::AiSequence::AiCombat> combat(new ESM::AiSequence::AiCombat());
combat->mTargetActorId = mTargetActorId;
ESM::AiSequence::AiPackageContainer package;
package.mType = ESM::AiSequence::Ai_Combat;
package.mPackage = combat.release();
sequence.mPackages.push_back(package);
}
void AiCombatStorage::startCombatMove(bool isDistantCombat, float distToTarget, float rangeAttack, const MWWorld::Ptr& actor, const MWWorld::Ptr& target)
{
// get the range of the target's weapon
MWWorld::Ptr targetWeapon = MWWorld::Ptr();
const MWWorld::Class& targetClass = target.getClass();
if (targetClass.hasInventoryStore(target))
{
MWMechanics::WeaponType weapType = WeapType_None;
MWWorld::ContainerStoreIterator weaponSlot =
MWMechanics::getActiveWeapon(targetClass.getCreatureStats(target), targetClass.getInventoryStore(target), &weapType);
if (weapType != WeapType_PickProbe && weapType != WeapType_Spell && weapType != WeapType_None && weapType != WeapType_HandToHand)
targetWeapon = *weaponSlot;
}
bool targetUsesRanged = false;
float rangeAttackOfTarget = ActionWeapon(targetWeapon).getCombatRange(targetUsesRanged);
if (mMovement.mPosition[0] || mMovement.mPosition[1])
{
mTimerCombatMove = 0.1f + 0.1f * Misc::Rng::rollClosedProbability();
mCombatMove = true;
}
// dodge movements (for NPCs and bipedal creatures)
else if (actor.getClass().isBipedal(actor))
{
// apply sideway movement (kind of dodging) with some probability
// if actor is within range of target's weapon
if (distToTarget <= rangeAttackOfTarget && Misc::Rng::rollClosedProbability() < 0.25)
{
mMovement.mPosition[0] = Misc::Rng::rollProbability() < 0.5 ? 1.0f : -1.0f; // to the left/right
mTimerCombatMove = 0.05f + 0.15f * Misc::Rng::rollClosedProbability();
mCombatMove = true;
}
}
// Backing up behaviour
// Actor backs up slightly further away than opponent's weapon range
// (in vanilla - only as far as oponent's weapon range),
// or not at all if opponent is using a ranged weapon
if (isDistantCombat)
{
// actor should not back up into water
if (MWBase::Environment::get().getWorld()->isUnderwater(MWWorld::ConstPtr(actor), 0.5f))
return;
if (!targetUsesRanged && distToTarget <= rangeAttackOfTarget*1.5) // Don't back up if the target is wielding ranged weapon
mMovement.mPosition[1] = -1;
}
}
void AiCombatStorage::updateCombatMove(float duration)
{
if (mCombatMove)
{
mTimerCombatMove -= duration;
if (mTimerCombatMove <= 0)
{
stopCombatMove();
}
}
}
void AiCombatStorage::stopCombatMove()
{
mTimerCombatMove = 0;
mMovement.mPosition[1] = mMovement.mPosition[0] = 0;
mCombatMove = false;
}
void AiCombatStorage::startAttackIfReady(const MWWorld::Ptr& actor, CharacterController& characterController,
const ESM::Weapon* weapon, bool distantCombat)
{
if (mReadyToAttack && characterController.readyToStartAttack())
{
if (mAttackCooldown <= 0)
{
mAttack = true; // attack starts just now
characterController.setAttackingOrSpell(true);
if (!distantCombat)
characterController.setAIAttackType(chooseBestAttack(weapon));
mStrength = Misc::Rng::rollClosedProbability();
const MWWorld::ESMStore &store = MWBase::Environment::get().getWorld()->getStore();
float baseDelay = store.get<ESM::GameSetting>().find("fCombatDelayCreature")->getFloat();
if (actor.getClass().isNpc())
{
baseDelay = store.get<ESM::GameSetting>().find("fCombatDelayNPC")->getFloat();
//say a provoking combat phrase
int chance = store.get<ESM::GameSetting>().find("iVoiceAttackOdds")->getInt();
if (Misc::Rng::roll0to99() < chance)
{
MWBase::Environment::get().getDialogueManager()->say(actor, "attack");
}
}
mAttackCooldown = std::min(baseDelay + 0.01 * Misc::Rng::roll0to99(), baseDelay + 0.9);
}
else
mAttackCooldown -= AI_REACTION_TIME;
}
}
void AiCombatStorage::updateAttack(CharacterController& characterController)
{
if (mAttack && (characterController.getAttackStrength() >= mStrength || characterController.readyToPrepareAttack()))
{
mAttack = false;
}
characterController.setAttackingOrSpell(mAttack);
}
void AiCombatStorage::stopAttack()
{
mMovement.mPosition[0] = 0;
mMovement.mPosition[1] = 0;
mMovement.mPosition[2] = 0;
mReadyToAttack = false;
mAttack = false;
}
void AiCombatStorage::startFleeing()
{
stopFleeing();
mFleeState = FleeState_Idle;
}
void AiCombatStorage::stopFleeing()
{
mMovement.mPosition[0] = 0;
mMovement.mPosition[1] = 0;
mMovement.mPosition[2] = 0;
mFleeState = FleeState_None;
mFleeDest = ESM::Pathgrid::Point(0, 0, 0);
}
bool AiCombatStorage::isFleeing()
{
return mFleeState != FleeState_None;
}
}
namespace
{
std::string chooseBestAttack(const ESM::Weapon* weapon)
{
std::string attackType;
if (weapon != NULL)
{
//the more damage attackType deals the more probability it has
int slash = (weapon->mData.mSlash[0] + weapon->mData.mSlash[1])/2;
int chop = (weapon->mData.mChop[0] + weapon->mData.mChop[1])/2;
int thrust = (weapon->mData.mThrust[0] + weapon->mData.mThrust[1])/2;
float roll = Misc::Rng::rollClosedProbability() * (slash + chop + thrust);
if(roll <= slash)
attackType = "slash";
else if(roll <= (slash + thrust))
attackType = "thrust";
else
attackType = "chop";
}
else
MWMechanics::CharacterController::setAttackTypeRandomly(attackType);
return attackType;
}
osg::Vec3f AimDirToMovingTarget(const MWWorld::Ptr& actor, const MWWorld::Ptr& target, const osg::Vec3f& vLastTargetPos,
float duration, int weapType, float strength)
{
float projSpeed;
// get projectile speed (depending on weapon type)
if (weapType == ESM::Weapon::MarksmanThrown)
{
static float fThrownWeaponMinSpeed =
MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fThrownWeaponMinSpeed")->getFloat();
static float fThrownWeaponMaxSpeed =
MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fThrownWeaponMaxSpeed")->getFloat();
projSpeed =
fThrownWeaponMinSpeed + (fThrownWeaponMaxSpeed - fThrownWeaponMinSpeed) * strength;
}
else
{
static float fProjectileMinSpeed =
MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fProjectileMinSpeed")->getFloat();
static float fProjectileMaxSpeed =
MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fProjectileMaxSpeed")->getFloat();
projSpeed =
fProjectileMinSpeed + (fProjectileMaxSpeed - fProjectileMinSpeed) * strength;
}
// idea: perpendicular to dir to target speed components of target move vector and projectile vector should be the same
osg::Vec3f vTargetPos = target.getRefData().getPosition().asVec3();
osg::Vec3f vDirToTarget = MWBase::Environment::get().getWorld()->aimToTarget(actor, target);
float distToTarget = vDirToTarget.length();
osg::Vec3f vTargetMoveDir = vTargetPos - vLastTargetPos;
vTargetMoveDir /= duration; // |vTargetMoveDir| is target real speed in units/sec now
osg::Vec3f vPerpToDir = vDirToTarget ^ osg::Vec3f(0,0,1); // cross product
vPerpToDir.normalize();
osg::Vec3f vDirToTargetNormalized = vDirToTarget;
vDirToTargetNormalized.normalize();
// dot product
float velPerp = vTargetMoveDir * vPerpToDir;
float velDir = vTargetMoveDir * vDirToTargetNormalized;
// time to collision between target and projectile
float t_collision;
float projVelDirSquared = projSpeed * projSpeed - velPerp * velPerp;
osg::Vec3f vTargetMoveDirNormalized = vTargetMoveDir;
vTargetMoveDirNormalized.normalize();
float projDistDiff = vDirToTarget * vTargetMoveDirNormalized; // dot product
projDistDiff = std::sqrt(distToTarget * distToTarget - projDistDiff * projDistDiff);
if (projVelDirSquared > 0)
t_collision = projDistDiff / (std::sqrt(projVelDirSquared) - velDir);
else t_collision = 0; // speed of projectile is not enough to reach moving target
return vDirToTarget + vTargetMoveDir * t_collision;
}
}