ProjectileEntity.cpp

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// ProjectileEntity.cpp

// Implements the cProjectileEntity class representing the common base class for projectiles, as well as individual projectile types

#include "Globals.h"

#include "../Bindings/PluginManager.h"
#include "ProjectileEntity.h"
#include "../ClientHandle.h"
#include "../LineBlockTracer.h"
#include "../BoundingBox.h"
#include "../ChunkMap.h"
#include "../Chunk.h"

#include "ArrowEntity.h"
#include "ThrownEggEntity.h"
#include "ThrownEnderPearlEntity.h"
#include "ExpBottleEntity.h"
#include "ThrownSnowballEntity.h"
#include "FireChargeEntity.h"
#include "FireworkEntity.h"
#include "GhastFireballEntity.h"
#include "WitherSkullEntity.h"
#include "SplashPotionEntity.h"
#include "Player.h"





#define ANGLE_TO_PROTO(X) static_cast<Byte>(X * 255 / 360)





// cProjectileTracerCallback:

class cProjectileTracerCallback :
    public cBlockTracer::cCallbacks
{
public:
    cProjectileTracerCallback(cProjectileEntity * a_Projectile) :
        m_Projectile(a_Projectile),
        m_SlowdownCoeff(0.99)  // Default slowdown when not in water
    {
    }

    double GetSlowdownCoeff(void) const { return m_SlowdownCoeff; }

protected:
    cProjectileEntity * m_Projectile;
    double m_SlowdownCoeff;

    // cCallbacks overrides:
    virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
    {
        /*
        // DEBUG:
        FLOGD("Hit block {0}:{1} at {2} face {3}, {4} ({5})",
            a_BlockType, a_BlockMeta,
            Vector3i{a_BlockX, a_BlockY, a_BlockZ}, a_EntryFace,
            cBlockInfo::IsSolid(a_BlockType) ? "solid" : "non-solid",
            ItemToString(cItem(a_BlockType, 1, a_BlockMeta))
        );
        */

        if (cBlockInfo::IsSolid(a_BlockType))
        {
            // The projectile hit a solid block, calculate the exact hit coords:
            cBoundingBox bb(a_BlockX, a_BlockX + 1, a_BlockY, a_BlockY + 1, a_BlockZ, a_BlockZ + 1);  // Bounding box of the block hit
            const Vector3d LineStart = m_Projectile->GetPosition();  // Start point for the imaginary line that goes through the block hit
            const Vector3d LineEnd = LineStart + m_Projectile->GetSpeed();  // End point for the imaginary line that goes through the block hit
            double LineCoeff = 0;  // Used to calculate where along the line an intersection with the bounding box occurs
            eBlockFace Face;  // Face hit

            if (bb.CalcLineIntersection(LineStart, LineEnd, LineCoeff, Face))
            {
                Vector3d Intersection = LineStart + m_Projectile->GetSpeed() * LineCoeff;  // Point where projectile goes into the hit block

                if (cPluginManager::Get()->CallHookProjectileHitBlock(*m_Projectile, a_BlockX, a_BlockY, a_BlockZ, Face, Intersection))
                {
                    return false;
                }

                m_Projectile->OnHitSolidBlock(Intersection, Face);
                return true;
            }
            else
            {
                LOGD("WEIRD! block tracer reports a hit, but BBox tracer doesn't. Ignoring the hit.");
            }
        }

        // Convey some special effects from special blocks:
        switch (a_BlockType)
        {
            case E_BLOCK_LAVA:
            case E_BLOCK_STATIONARY_LAVA:
            {
                m_Projectile->StartBurning(30);
                m_SlowdownCoeff = std::min(m_SlowdownCoeff, 0.9);  // Slow down to 0.9* the speed each tick when moving through lava
                break;
            }
            case E_BLOCK_WATER:
            case E_BLOCK_STATIONARY_WATER:
            {
                m_Projectile->StopBurning();
                m_SlowdownCoeff = std::min(m_SlowdownCoeff, 0.8);  // Slow down to 0.8* the speed each tick when moving through water
                break;
            }
        }  // switch (a_BlockType)

        // Continue tracing
        return false;
    }
} ;





// cProjectileEntityCollisionCallback:

class cProjectileEntityCollisionCallback
{
public:
    cProjectileEntityCollisionCallback(cProjectileEntity * a_Projectile, const Vector3d & a_Pos, const Vector3d & a_NextPos) :
        m_Projectile(a_Projectile),
        m_Pos(a_Pos),
        m_NextPos(a_NextPos),
        m_MinCoeff(1),
        m_HitEntity(nullptr)
    {
    }


    bool operator () (cEntity & a_Entity)
    {
        if (
            (&a_Entity == m_Projectile) ||          // Do not check collisions with self
            (a_Entity.GetUniqueID() == m_Projectile->GetCreatorUniqueID())  // Do not check whoever shot the projectile
        )
        {
            // Don't check creator only for the first 5 ticks so that projectiles can collide with the creator
            if (m_Projectile->GetTicksAlive() <= 5)
            {
                return false;
            }
        }

        cBoundingBox EntBox(a_Entity.GetPosition(), a_Entity.GetWidth() / 2, a_Entity.GetHeight());

        // Instead of colliding the bounding box with another bounding box in motion, we collide an enlarged bounding box with a hairline.
        // The results should be good enough for our purposes
        double LineCoeff;
        eBlockFace Face;
        EntBox.Expand(m_Projectile->GetWidth() / 2, m_Projectile->GetHeight() / 2, m_Projectile->GetWidth() / 2);
        if (!EntBox.CalcLineIntersection(m_Pos, m_NextPos, LineCoeff, Face))
        {
            // No intersection whatsoever
            return false;
        }

        if (
            !a_Entity.IsMob() &&
            !a_Entity.IsMinecart() &&
            (
                !a_Entity.IsPlayer() ||
                static_cast<cPlayer &>(a_Entity).IsGameModeSpectator()
            ) &&
            !a_Entity.IsBoat()
        )
        {
            // Not an entity that interacts with a projectile
            return false;
        }

        if (cPluginManager::Get()->CallHookProjectileHitEntity(*m_Projectile, a_Entity))
        {
            // A plugin disagreed.
            return false;
        }

        if (LineCoeff < m_MinCoeff)
        {
            // The entity is closer than anything we've stored so far, replace it as the potential victim
            m_MinCoeff = LineCoeff;
            m_HitEntity = &a_Entity;
        }

        // Don't break the enumeration, we want all the entities
        return false;
    }

    cEntity * GetHitEntity(void) const { return m_HitEntity; }

    double GetMinCoeff(void) const { return m_MinCoeff; }

    bool HasHit(void) const { return (m_MinCoeff < 1); }

protected:
    cProjectileEntity * m_Projectile;
    const Vector3d & m_Pos;
    const Vector3d & m_NextPos;
    double m_MinCoeff;  // The coefficient of the nearest hit on the Pos line

    // Although it's bad(tm) to store entity ptrs from a callback, we can afford it here, because the entire callback
    // is processed inside the tick thread, so the entities won't be removed in between the calls and the final processing
    cEntity * m_HitEntity;  // The nearest hit entity
} ;





// cProjectileEntity:

cProjectileEntity::cProjectileEntity(eKind a_Kind, cEntity * a_Creator, Vector3d a_Pos, double a_Width, double a_Height):
    super(etProjectile, a_Pos, a_Width, a_Height),
    m_ProjectileKind(a_Kind),
    m_CreatorData(
        ((a_Creator != nullptr) ? a_Creator->GetUniqueID() : cEntity::INVALID_ID),
        ((a_Creator != nullptr) ? (a_Creator->IsPlayer() ? static_cast<cPlayer *>(a_Creator)->GetName() : "") : ""),
        ((a_Creator != nullptr) ? a_Creator->GetEquippedWeapon().m_Enchantments : cEnchantments())
    ),
    m_IsInGround(false)
{
    SetGravity(-12.0f);
    SetAirDrag(0.01f);
}





cProjectileEntity::cProjectileEntity(eKind a_Kind, cEntity * a_Creator, Vector3d a_Pos, Vector3d a_Speed, double a_Width, double a_Height):
    super(etProjectile, a_Pos, a_Width, a_Height),
    m_ProjectileKind(a_Kind),
    m_CreatorData(a_Creator->GetUniqueID(), a_Creator->IsPlayer() ? static_cast<cPlayer *>(a_Creator)->GetName() : "", a_Creator->GetEquippedWeapon().m_Enchantments),
    m_IsInGround(false)
{
    SetSpeed(a_Speed);
    SetYawFromSpeed();
    SetPitchFromSpeed();
    SetGravity(-12.0f);
    SetAirDrag(0.01f);
}





std::unique_ptr<cProjectileEntity> cProjectileEntity::Create(
    eKind a_Kind,
    cEntity * a_Creator,
    Vector3d a_Pos,
    const cItem * a_Item,
    const Vector3d * a_Speed
)
{
    Vector3d Speed;
    if (a_Speed != nullptr)
    {
        Speed = *a_Speed;
    }

    switch (a_Kind)
    {
        case pkArrow:         return cpp14::make_unique<cArrowEntity>           (a_Creator, a_Pos, Speed);
        case pkEgg:           return cpp14::make_unique<cThrownEggEntity>       (a_Creator, a_Pos, Speed);
        case pkEnderPearl:    return cpp14::make_unique<cThrownEnderPearlEntity>(a_Creator, a_Pos, Speed);
        case pkSnowball:      return cpp14::make_unique<cThrownSnowballEntity>  (a_Creator, a_Pos, Speed);
        case pkGhastFireball: return cpp14::make_unique<cGhastFireballEntity>   (a_Creator, a_Pos, Speed);
        case pkFireCharge:    return cpp14::make_unique<cFireChargeEntity>      (a_Creator, a_Pos, Speed);
        case pkExpBottle:     return cpp14::make_unique<cExpBottleEntity>       (a_Creator, a_Pos, Speed);
        case pkSplashPotion:  return cpp14::make_unique<cSplashPotionEntity>    (a_Creator, a_Pos, Speed, *a_Item);
        case pkWitherSkull:   return cpp14::make_unique<cWitherSkullEntity>     (a_Creator, a_Pos, Speed);
        case pkFirework:
        {
            ASSERT(a_Item != nullptr);
            if (a_Item->m_FireworkItem.m_Colours.empty())
            {
                return nullptr;
            }

            return cpp14::make_unique<cFireworkEntity>(a_Creator, a_Pos, *a_Item);
        }
        case pkFishingFloat: break;
    }

    LOGWARNING("%s: Unknown projectile kind: %d", __FUNCTION__, a_Kind);
    return nullptr;
}





void cProjectileEntity::OnHitSolidBlock(Vector3d a_HitPos, eBlockFace a_HitFace)
{
    // Set the position based on what face was hit:
    SetPosition(a_HitPos);
    SetSpeed(0, 0, 0);

    // DEBUG:
    FLOGD("Projectile {0}: pos {1:.02f}, hit solid block at face {2}",
        m_UniqueID, a_HitPos, a_HitFace
    );

    m_IsInGround = true;
}





void cProjectileEntity::OnHitEntity(cEntity & a_EntityHit, Vector3d a_HitPos)
{
    UNUSED(a_HitPos);

    // If we were created by a player and we hit a pawn, notify attacking player's wolves
    if (a_EntityHit.IsPawn() && (GetCreatorName() != ""))
    {
        auto EntityHit = static_cast<cPawn *>(&a_EntityHit);
        m_World->DoWithEntityByID(GetCreatorUniqueID(), [=](cEntity & a_Hitter)
            {
                static_cast<cPlayer&>(a_Hitter).NotifyNearbyWolves(EntityHit, true);
                return true;
            }
        );
    }
}





AString cProjectileEntity::GetMCAClassName(void) const
{
    switch (m_ProjectileKind)
    {
        case pkArrow:         return "Arrow";
        case pkSnowball:      return "Snowball";
        case pkEgg:           return "Egg";
        case pkGhastFireball: return "Fireball";
        case pkFireCharge:    return "SmallFireball";
        case pkEnderPearl:    return "ThrownEnderpearl";
        case pkExpBottle:     return "ThrownExpBottle";
        case pkSplashPotion:  return "SplashPotion";
        case pkWitherSkull:   return "WitherSkull";
        case pkFirework:      return "Firework";
        case pkFishingFloat:  return "";  // Unknown, perhaps MC doesn't save this?
    }
    UNREACHABLE("Unsupported projectile kind");
}





void cProjectileEntity::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
{
    super::Tick(a_Dt, a_Chunk);
    if (!IsTicking())
    {
        // The base class tick destroyed us
        return;
    }
    BroadcastMovementUpdate();
}





void cProjectileEntity::HandlePhysics(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
{
    if (m_IsInGround)
    {
        // Already-grounded projectiles don't move at all
        return;
    }

    auto DtSec = std::chrono::duration_cast<std::chrono::duration<double>>(a_Dt);

    const Vector3d DeltaSpeed = GetSpeed() * DtSec.count();
    const Vector3d Pos = GetPosition();
    const Vector3d NextPos = Pos + DeltaSpeed;

    // Test for entity collisions:
    cProjectileEntityCollisionCallback EntityCollisionCallback(this, Pos, NextPos);
    a_Chunk.ForEachEntity(EntityCollisionCallback);
    if (EntityCollisionCallback.HasHit())
    {
        // An entity was hit:
        Vector3d HitPos = Pos + (NextPos - Pos) * EntityCollisionCallback.GetMinCoeff();

        // DEBUG:
        FLOGD("Projectile {0} has hit an entity {1} ({2}) at {3:.02f} (coeff {4:.03f})",
            m_UniqueID,
            EntityCollisionCallback.GetHitEntity()->GetUniqueID(),
            EntityCollisionCallback.GetHitEntity()->GetClass(),
            HitPos,
            EntityCollisionCallback.GetMinCoeff()
        );

        OnHitEntity(*(EntityCollisionCallback.GetHitEntity()), HitPos);
        if (!IsTicking())
        {
            return;  // We were destroyed by an override of OnHitEntity
        }
    }
    // TODO: Test the entities in the neighboring chunks, too

    // Trace the tick's worth of movement as a line:
    cProjectileTracerCallback TracerCallback(this);
    if (!cLineBlockTracer::Trace(*m_World, TracerCallback, Pos, NextPos))
    {
        // Something has been hit, abort all other processing
        return;
    }
    // The tracer also checks the blocks for slowdown blocks - water and lava - and stores it for later in its SlowdownCoeff

    // Update the position:
    SetPosition(NextPos);

    // Add slowdown and gravity effect to the speed:
    Vector3d NewSpeed(GetSpeed());
    NewSpeed.y += m_Gravity * DtSec.count();
    NewSpeed -= NewSpeed * (m_AirDrag * 20.0f) * DtSec.count();
    SetSpeed(NewSpeed);
    SetYawFromSpeed();
    SetPitchFromSpeed();

    /*
    FLOGD("Projectile {0}: pos {1:.02f}, speed {2:.02f}, rot {{{3:.02f}, {4:.02f}}}",
        m_UniqueID, GetPos(), GetSpeed(), GetYaw(), GetPitch()
    );
    */
}





void cProjectileEntity::SpawnOn(cClientHandle & a_Client)
{
    // Default spawning - use the projectile kind to spawn an object:
    a_Client.SendSpawnObject(*this, m_ProjectileKind, 12, ANGLE_TO_PROTO(GetYaw()), ANGLE_TO_PROTO(GetPitch()));
    a_Client.SendEntityMetadata(*this);
}





void cProjectileEntity::CollectedBy(cPlayer & a_Dest)
{
    // Overriden in arrow
    UNUSED(a_Dest);
}