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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#include "BombDropper.h"
#include "WeaponDef.h"
#include "Game/GameHelper.h"
#include "Sim/Misc/GlobalSynced.h"
#include "Sim/Misc/Team.h"
#include "Map/MapInfo.h"
#include "Sim/Projectiles/WeaponProjectiles/WeaponProjectileFactory.h"
#include "Sim/Units/Unit.h"
#include "Sim/Units/UnitDef.h"
#include "System/SpringMath.h"
#include "System/Log/ILog.h"
CR_BIND_DERIVED(CBombDropper, CWeapon, )
CR_REG_METADATA(CBombDropper,(
CR_MEMBER(dropTorpedoes),
CR_MEMBER(torpMoveRange),
CR_MEMBER(tracking)
))
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
CBombDropper::CBombDropper(CUnit* owner, const WeaponDef* def, bool useTorps)
: CWeapon(owner, def)
, dropTorpedoes(useTorps)
{
// null happens when loading
if (def != nullptr) {
torpMoveRange = def->range * useTorps;
tracking = def->turnrate * def->tracks;
}
onlyForward = true;
doTargetGroundPos = true;
noAutoTarget = true;
maxForwardAngleDif = -1.0f;
}
float CBombDropper::GetPredictedImpactTime(float3 impactPos) const
{
if (weaponMuzzlePos.y <= impactPos.y)
return 0.0f;
// Definitions:
// d := (mostly negative) distance from plane to explosion position
// v := vertical plane speed (bomb starts with it)
// g := myGravity (negative)
//
// We want to solve: d = v * t + 0.5 * g * t^2
// <=> 0 = t^2 + (2v/g) * t - (2d/g)
// -> a=2v/g b=-(2d/g)
// Using pq-formula there are 2 solutions (we want the t>0 +solution):
// x(+,-) = -p +- sqrt((p^2 - q) with p=a/2 q=b
// => = -v/g + sqrt(v^2/g^2 + 2d/g)
// <=> = -v/g + sqrt( (v^2 + 2dg)/g^2 )
// <=> = -v/g + sqrt(v^2 + 2dg) / |g|
// Now we use (g is negative!): +1/|g| = +1/(-g) = -1/g
// => = (-v - sqrt(v^2 + 2dg)) / g
// <=> = -(v + sqrt(v^2 + 2dg)) / g
const float d = impactPos.y - weaponMuzzlePos.y;
const float v = owner->speed.y;
const float g = (weaponDef->myGravity == 0) ? mapInfo->map.gravity: -weaponDef->myGravity;
const float tt = v*v + 2.f * d * g;
return ((tt >= 0.0f)? ((-v - math::sqrt(tt)) / g) : 0.0f);
}
bool CBombDropper::TestTarget(const float3 pos, const SWeaponTarget& trg) const
{
// assume we can still drop bombs on *partially* submerged targets
if (!dropTorpedoes && TargetUnderWater(pos, trg))
return false;
// assume we can drop torpedoes on any partially or fully submerged target
if (dropTorpedoes && !TargetInWater(pos, trg))
return false;
return CWeapon::TestTarget(pos, trg);
}
bool CBombDropper::TestRange(const float3 pos, const SWeaponTarget& trg) const
{
// bombs always fall down
if (aimFromPos.y < pos.y)
return false;
const float fallTime = GetPredictedImpactTime(pos);
const float dropDist = std::max(1, salvoSize - 1) * salvoDelay * owner->speed.Length2D() * 0.5f;
// torpedoes especially should not be dropped if the
// target position is already behind owner's position
const float torpDist = torpMoveRange * (owner->frontdir.dot(pos - aimFromPos) > 0.0f);
return (pos.SqDistance2D(aimFromPos + owner->speed * fallTime) < Square(dropDist + torpDist));
}
bool CBombDropper::CanFire(bool ignoreAngleGood, bool ignoreTargetType, bool ignoreRequestedDir) const
{
return CWeapon::CanFire(true, ignoreTargetType, true);
}
void CBombDropper::FireImpl(const bool scriptCall)
{
const float predict = GetPredictedImpactTime(currentTargetPos);
if (dropTorpedoes) {
float3 launchSpeed = owner->speed;
// if owner is a hovering aircraft, use a fixed launching speed [?? WTF]
if (owner->unitDef->IsHoveringAirUnit()) {
launchSpeed = wantedDir * 5.0f;
}
ProjectileParams params = GetProjectileParams();
params.pos = weaponMuzzlePos;
params.end = currentTargetPos;
params.speed = launchSpeed;
params.ttl = (weaponDef->flighttime == 0)? ((range / projectileSpeed) + 15 + predict): weaponDef->flighttime;
params.tracking = tracking;
assert(weaponDef->projectileType == WEAPON_TORPEDO_PROJECTILE);
WeaponProjectileFactory::LoadProjectile(params);
} else {
// fudge a bit better lateral aim to compensate for imprecise aircraft steering
float3 dif = (currentTargetPos - weaponMuzzlePos) * XZVector;
float3 dir = owner->speed;
dir = dir.SafeNormalize();
// add a random spray
dir += (gsRNG.NextVector() * SprayAngleExperience() + SalvoErrorExperience());
dir.y = std::min(0.0f, dir.y);
dir = dir.SafeNormalize();
dif -= (dir * dif.dot(dir));
dif /= std::max(0.01f, predict);
if (dif.SqLength() > 1.0f) {
dif /= dif.Length();
}
ProjectileParams params = GetProjectileParams();
params.pos = weaponMuzzlePos;
params.end = currentTargetPos;
params.speed = owner->speed + dif;
params.ttl = 1000;
params.gravity = (weaponDef->myGravity == 0)? mapInfo->map.gravity: -weaponDef->myGravity;
assert(weaponDef->projectileType == WEAPON_EXPLOSIVE_PROJECTILE);
WeaponProjectileFactory::LoadProjectile(params);
}
}
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