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Protocol: Use correct calculation for delta movements (#5455)

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* Protocol: Use correct calculation for delta movements
This commit is contained in:
Tiger Wang 2022-11-08 22:14:45 +00:00 committed by GitHub
parent 5907df6808
commit 7a73fd467c
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GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 56 additions and 38 deletions
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18
src/ByteBuffer.cpp
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@ -214,6 +214,24 @@ size_t cByteBuffer::GetReadableSpace(void) const
bool cByteBuffer::CanBEInt8Represent(int a_Value)
{
return (-128 <= a_Value) && (a_Value <= 127);
}
bool cByteBuffer::CanBEInt16Represent(int a_Value)
{
return (-32768 <= a_Value) && (a_Value <= 32767);
}
bool cByteBuffer::CanReadBytes(size_t a_Count) const
{
CHECK_THREAD

9
src/ByteBuffer.h
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@ -31,6 +31,7 @@ their own synchronization.
class cByteBuffer
{
public:
cByteBuffer(size_t a_BufferSize);
~cByteBuffer();
@ -47,7 +48,13 @@ public:
size_t GetReadableSpace(void) const;
/** Returns the current data start index. For debugging purposes. */
size_t GetDataStart(void) const { return m_DataStart; }
size_t GetDataStart(void) const { return m_DataStart; }
/** Returns if the given value can fit in a protocol big-endian 8 bit integer. */
static bool CanBEInt8Represent(int a_Value);
/** Returns if the given value can fit in a protocol big-endian 16 bit integer. */
static bool CanBEInt16Represent(int a_Value);
/** Returns true if the specified amount of bytes are available for reading */
bool CanReadBytes(size_t a_Count) const;

5
src/Entities/Entity.cpp
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@ -1970,7 +1970,7 @@ void cEntity::BroadcastMovementUpdate(const cClientHandle * a_Exclude)
return;
}
if (GetSpeed().SqrLength() > 0.001)
if (m_Speed.HasNonZeroLength())
{
// Movin'
m_World->BroadcastEntityVelocity(*this, a_Exclude);
@ -1986,8 +1986,7 @@ void cEntity::BroadcastMovementUpdate(const cClientHandle * a_Exclude)
m_bHasSentNoSpeed = true;
}
Vector3i Diff = (GetPosition() * 32.0).Floor() - (m_LastSentPosition * 32.0).Floor();
if (Diff.HasNonZeroLength()) // Have we moved?
if ((m_Position - m_LastSentPosition).HasNonZeroLength()) // Have we moved?
{
m_World->BroadcastEntityPosition(*this, a_Exclude);

41
src/Protocol/Protocol_1_8.cpp
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@ -579,12 +579,15 @@ void cProtocol_1_8_0::SendEntityPosition(const cEntity & a_Entity)
{
ASSERT(m_State == 3); // In game mode?
const auto Delta = (a_Entity.GetPosition() - a_Entity.GetLastSentPosition()) * 32;
const auto Delta = (a_Entity.GetPosition() * 32).Floor() - (a_Entity.GetLastSentPosition() * 32).Floor();
// Limitations of a byte
static const auto Max = std::numeric_limits<Int8>::max();
if ((std::abs(Delta.x) <= Max) && (std::abs(Delta.y) <= Max) && (std::abs(Delta.z) <= Max))
// Ensure that the delta has enough precision and is within range of a BEInt8:
if (
Delta.HasNonZeroLength() &&
cByteBuffer::CanBEInt8Represent(Delta.x) &&
cByteBuffer::CanBEInt8Represent(Delta.y) &&
cByteBuffer::CanBEInt8Represent(Delta.z)
)
{
const auto Move = static_cast<Vector3<Int8>>(Delta);
@ -613,8 +616,16 @@ void cProtocol_1_8_0::SendEntityPosition(const cEntity & a_Entity)
return;
}
// Too big a movement, do a teleport
SendEntityTeleport(a_Entity);
// Too big or small a movement, do a teleport.
cPacketizer Pkt(*this, pktTeleportEntity);
Pkt.WriteVarInt32(a_Entity.GetUniqueID());
Pkt.WriteFPInt(a_Entity.GetPosX());
Pkt.WriteFPInt(a_Entity.GetPosY());
Pkt.WriteFPInt(a_Entity.GetPosZ());
Pkt.WriteByteAngle(a_Entity.GetYaw());
Pkt.WriteByteAngle(a_Entity.GetPitch());
Pkt.WriteBool(a_Entity.IsOnGround());
}
@ -4202,22 +4213,6 @@ void cProtocol_1_8_0::HandlePacket(cByteBuffer & a_Buffer)
void cProtocol_1_8_0::SendEntityTeleport(const cEntity & a_Entity)
{
cPacketizer Pkt(*this, pktTeleportEntity);
Pkt.WriteVarInt32(a_Entity.GetUniqueID());
Pkt.WriteFPInt(a_Entity.GetPosX());
Pkt.WriteFPInt(a_Entity.GetPosY());
Pkt.WriteFPInt(a_Entity.GetPosZ());
Pkt.WriteByteAngle(a_Entity.GetYaw());
Pkt.WriteByteAngle(a_Entity.GetPitch());
Pkt.WriteBool(a_Entity.IsOnGround());
}
void cProtocol_1_8_0::StartEncryption(const Byte * a_Key)
{
m_Encryptor.Init(a_Key, a_Key);

5
src/Protocol/Protocol_1_8.h
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@ -270,10 +270,5 @@ private:
/** Handle a complete packet stored in the given buffer. */
void HandlePacket(cByteBuffer & a_Buffer);
/** Sends an entity teleport packet.
Mitigates a 1.8 bug where the position in the entity spawn packet is ignored,
and so entities don't show up until a teleport is sent. */
void SendEntityTeleport(const cEntity & a_Entity);
void StartEncryption(const Byte * a_Key);
} ;

16
src/Protocol/Protocol_1_9.cpp
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@ -307,12 +307,15 @@ void cProtocol_1_9_0::SendEntityPosition(const cEntity & a_Entity)
{
ASSERT(m_State == 3); // In game mode?
const auto Delta = (a_Entity.GetPosition() - a_Entity.GetLastSentPosition()) * 32 * 128;
const auto Delta = (a_Entity.GetPosition() * 32 * 128).Floor() - (a_Entity.GetLastSentPosition() * 32 * 128).Floor();
// Limitations of a short
static const auto Max = std::numeric_limits<Int16>::max();
if ((std::abs(Delta.x) <= Max) && (std::abs(Delta.y) <= Max) && (std::abs(Delta.z) <= Max))
// Ensure that the delta has enough precision and is within range of a BEInt16:
if (
Delta.HasNonZeroLength() &&
cByteBuffer::CanBEInt16Represent(Delta.x) &&
cByteBuffer::CanBEInt16Represent(Delta.y) &&
cByteBuffer::CanBEInt16Represent(Delta.z)
)
{
const auto Move = static_cast<Vector3<Int16>>(Delta);
@ -341,7 +344,8 @@ void cProtocol_1_9_0::SendEntityPosition(const cEntity & a_Entity)
return;
}
// Too big a movement, do a teleport
// Too big or small a movement, do a teleport.
cPacketizer Pkt(*this, pktTeleportEntity);
Pkt.WriteVarInt32(a_Entity.GetUniqueID());
Pkt.WriteBEDouble(a_Entity.GetPosX());