Fix set player position flag

docs/Get-started.md

@@ -80,3 +80,53 @@ client.networkChannel.sendPacket(
     ServerboundChatCommandPacket(command = "say Hello from libmc")
 )
 ```
+
+# Respond velocity and update client motion
+
+> This part uses math calculations
+
+When joined to the level(aka `world`), the server will send a packet 
+`ClientboundSetEntityVelocityPacket` to the client, packet contains a vec3 and entity id,
+The client sync this data to the player and sends it to the server during the next tick loop
+to inform the server: "Hi, I know my current position; here is the result of my calculations. I'm sending it to you".
+
+```kotlin
+private var entityId = -1
+private var motionX = 0
+private var motionY = 0
+private var motionZ = 0
+private var isOnGround = false
+
+fun main() {
+    // Set entity id
+    client.onPacket<ClientboundLoginPlayPacket> { entityId = it.entityId }
+
+    client.onPacket<ClientboundSetEntityVelocityPacket> {
+        if (it.entityId == entityId) {
+            motionX = it.velocity.x / 8000.0
+            motionY = it.velocity.y / 8000.0
+            motionZ = it.velocity.z / 8000.0
+            if (client.motionY > 0) client.isOnGround = false
+        }
+    }
+
+    // Update current position and velocity 
+    client.onTick {
+        if (client.stateMachine.currentState != ProtocolState.PLAY) return@registerListener
+        syncPlayerPosition()
+    }
+}
+
+internal suspend fun syncPlayerPosition() {
+    position.x += motionX
+    position.y += motionY
+    position.z += motionZ
+    motionX *= 0.91
+    motionY *= 0.98
+    motionZ *= 0.91
+    if (!isOnGround) motionY -= 0.08 else {
+        if (motionY < 0) motionY = 0.0
+    }
+    networkChannel.sendPacket(ServerboundSetPlayerPositionPacket(position.x, position.y, position.z, isOnGround))
+}
+```

libmc-common/src/commonMain/kotlin/cn/rtast/libmc/crypto/ProtocolContext.kt

@@ -25,7 +25,7 @@ public class ProtocolContextBuilder(private val onlineMode: Boolean) {
                 if (::authProvider.isInitialized) authProvider else error("authProvider is required in online mode")
             } else if (::authProvider.isInitialized) authProvider else null,
 
-            engine = if (::socketEngine.isInitialized) socketEngine else error("SocketEngine is not configured")
+            engine = if (::socketEngine.isInitialized) socketEngine else error("SocketEngine is not configured"),
         )
 }
 

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/client/ClientTickingLoop.kt

@@ -0,0 +1,127 @@
+/*
+ * Copyright © 2026 RTAkland
+ * Author: RTAkland
+ * Date: 2026/9/9
+ */
+
+package cn.rtast.libmc.protocol.client
+
+import cn.rtast.libmc.protocol.crypto.minecraftServerIdHash
+import cn.rtast.libmc.protocol.crypto.rsaEncrypt
+import cn.rtast.libmc.protocol.packet.configuration.clientbound.*
+import cn.rtast.libmc.protocol.packet.configuration.serverbound.*
+import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundDisconnectLoginPacket
+import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundHelloPacket
+import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundLoginSuccessPacket
+import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundSetCompressionPacket
+import cn.rtast.libmc.protocol.packet.login.serverbound.ServerboundKeyPacket
+import cn.rtast.libmc.protocol.packet.login.serverbound.ServerboundLoginAcknowledgedPacket
+import cn.rtast.libmc.protocol.packet.play.clientbound.*
+import cn.rtast.libmc.protocol.packet.play.serverbound.*
+import cn.rtast.libmc.protocol.protocol.state.ProtocolState
+import cn.rtast.libmc.protocol.util.generateRandom16Bytes
+import kotlinx.coroutines.*
+import kotlin.concurrent.Volatile
+import kotlin.math.abs
+import kotlin.time.Clock
+import kotlin.time.Duration.Companion.milliseconds
+
+public class ClientTickingLoop internal constructor(private val client: MinecraftClient) {
+    private var tickJob: Job? = null
+    private val tickIntervalMs = 50L
+    public var currentTick: Long = 0L
+        private set
+
+    @Volatile
+    public var isRunning: Boolean = false
+        private set
+
+    private val listeners = mutableListOf<suspend (Long) -> Unit>()
+    internal fun registerListener(action: suspend (Long) -> Unit) = listeners.add(action)
+
+    init {
+        client.onPacket<ClientboundLoginSuccessPacket> { handleLoginSuccess() }
+        client.onPacket<ClientboundSetCompressionPacket> { client.networkChannel.setCompression(it.threshold) }
+        client.onPacket<ClientboundHelloPacket> { handleEncryptRequest(it) }
+        client.onPacket<ClientboundDisconnectLoginPacket> { client.close() }
+        client.onPacket<ClientboundDisconnectPlayPacket> { client.close() }
+        client.onPacket<ClientboundDisconnectConfigurationPacket> { client.close() }
+        client.onPacket<ClientboundSetTimePacket> { syncServerTick(it.worldAge) }
+        client.onPacket<ClientboundPingPacket> { client.networkChannel.sendPacket(ServerboundPongPlayPacket(it.id)) }
+        client.onPacket<ClientboundSelectKnownPacksPacket> {
+            client.networkChannel.sendPacket(ServerboundSelectKnownPacksPacket(emptyList()))
+        }
+        client.onPacket<ClientboundCodeOfConductPacket> {
+            client.networkChannel.sendPacket(ServerboundAcceptCodeOfConductPacket)
+        }
+        client.onPacket<ClientboundKeepAlivePlayPacket> {
+            client.networkChannel.sendPacket(ServerboundKeepAlivePlayPacket(it.id))
+        }
+        client.onPacket<ClientboundPingConfigurationPacket> {
+            client.networkChannel.sendPacket(ServerboundPongConfigurationPacket(it.id))
+        }
+        client.onPacket<ClientboundStartConfigurationPacket> {
+            client.networkChannel.sendPacket(ServerboundConfigurationAcknowledgedPacket)
+            client.stateMachine.transitionTo(ProtocolState.CONFIGURATION)
+        }
+        client.onPacket<ClientboundKeepAliveConfigurationPacket> {
+            client.networkChannel.sendPacket(ServerboundKeepAliveConfigurationPacket(it.id))
+        }
+        client.onPacket<ClientboundFinishConfigurationPacket> {
+            client.networkChannel.sendPacket(ServerboundAckFinishConfigurationPacket)
+            client.stateMachine.transitionTo(ProtocolState.PLAY)
+        }
+    }
+
+    internal suspend fun handleLoginSuccess() {
+        client.networkChannel.sendPacket(ServerboundLoginAcknowledgedPacket)
+        client.stateMachine.transitionTo(ProtocolState.CONFIGURATION)
+    }
+
+    internal suspend fun handleEncryptRequest(packet: ClientboundHelloPacket) {
+        val sharedSecret = generateRandom16Bytes()
+        if (client.isOnlineMode) {
+            val serverHash = minecraftServerIdHash(packet.serverId, sharedSecret, packet.publicKey)
+            client.protocolContext.authProvider!!.joinServer(
+                "https://sessionserver.mojang.com/session/minecraft/join",
+                client.accessToken!!, client.uuid.toString().replace("-", ""), serverHash
+            )
+        }
+        val encryptedSecret = rsaEncrypt(packet.publicKey, sharedSecret)
+        val encryptedVerifyToken = rsaEncrypt(packet.publicKey, packet.verifyToken)
+        client.networkChannel.sendPacket(ServerboundKeyPacket(encryptedSecret, encryptedVerifyToken))
+        client.networkChannel.session.enableEncryption(sharedSecret)
+    }
+
+    internal fun syncServerTick(serverWorldAge: Long) {
+        if (abs(this.currentTick - serverWorldAge) > 2) this.currentTick = serverWorldAge
+    }
+
+    internal fun start() {
+        if (isRunning) return
+        isRunning = true
+        tickJob = client.launch(CoroutineName("LibMC-ClientTickingLoop")) {
+            var nextTickTime = Clock.System.now().toEpochMilliseconds()
+            while (isActive && isRunning) {
+                val now = Clock.System.now().toEpochMilliseconds()
+                if (now >= nextTickTime) {
+                    try {
+                        listeners.forEach { it.invoke(currentTick) }
+                    } catch (e: Exception) {
+                        if (e is CancellationException) throw e
+                        e.printStackTrace()
+                    }
+                    currentTick++
+                    nextTickTime += tickIntervalMs
+                    if (now - nextTickTime > tickIntervalMs * 5) nextTickTime = now + tickIntervalMs
+                } else delay((nextTickTime - now).milliseconds)
+            }
+        }
+    }
+
+    internal fun stop() {
+        isRunning = false
+        tickJob?.cancel()
+        tickJob = null
+    }
+}

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/client/MinecraftClient.kt

@@ -8,8 +8,6 @@ package cn.rtast.libmc.protocol.client
 
 import cn.rtast.libmc.crypto.ProtocolContext
 import cn.rtast.libmc.crypto.ProtocolContextBuilder
-import cn.rtast.libmc.protocol.event.InternalPacketDispatcher
-import cn.rtast.libmc.protocol.event.PacketEventDispatcher
 import cn.rtast.libmc.protocol.network.NetworkChannel
 import cn.rtast.libmc.protocol.packet.handshake.ServerboundHandshakePacket
 import cn.rtast.libmc.protocol.packet.login.serverbound.ServerboundLoginStartPacket
@@ -32,21 +30,26 @@ public class MinecraftClient internal constructor(
     internal val protocolContext: ProtocolContext,
 ) : PacketEventDispatcher(), CoroutineScope {
     internal val stateMachine = ClientStateMachine()
-    public val networkChannel: NetworkChannel = NetworkChannel(
-        host, port, stateMachine,
-        this, protocolContext
-    )
-
-    private val internalPacketDispatcher = InternalPacketDispatcher(this)
+    public val networkChannel: NetworkChannel = NetworkChannel(host, port, stateMachine, this, protocolContext)
     private val clientJob = SupervisorJob(parentJob)
     private var listenJob: Job? = null
 
     public val isOnlineMode: Boolean = accessToken != null
+
     public val transactionManager: TransactionIdManager = TransactionIdManager()
+    public val clientTickingLoop: ClientTickingLoop = ClientTickingLoop(this)
+
+    /**
+     * Register a client ticking event callback.
+     * NOTE: Blocking operations will **block** the bot thread.
+     * Using #launch to avoid blocking.
+     */
+    public fun onTick(action: suspend (Long) -> Unit): Unit = run { clientTickingLoop.registerListener(action) }
 
     public suspend fun connect(protocolVersion: Int = CURRENT_MINECRAFT_PROTOCOL_VERSION) {
         networkChannel.connect()
         startListening()
+        clientTickingLoop.start()
         networkChannel.sendPacket(
             ServerboundHandshakePacket(
                 protocolVersion,
@@ -63,7 +66,7 @@ public class MinecraftClient internal constructor(
     private fun startListening() {
         listenJob = launch {
             try {
-                while (isActive) internalPacketDispatcher.handleIncomingPackets(networkChannel.readNextPacket())
+                while (isActive) networkChannel.readNextPacket()
             } catch (e: Exception) {
                 if (e is CancellationException) throw e
                 if (isActive) {
@@ -77,6 +80,7 @@ public class MinecraftClient internal constructor(
 
     public fun close() {
         networkChannel.close()
+        clientTickingLoop.stop()
         clientJob.cancel()
     }
 

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/client/PacketEventDispatcher.kt

@@ -4,7 +4,7 @@
  * Date: 2026/9/5
  */
 
-package cn.rtast.libmc.protocol.event
+package cn.rtast.libmc.protocol.client
 
 import cn.rtast.libmc.packet.MinecraftPacket
 import cn.rtast.libmc.protocol.protocol.PacketDirection
@@ -14,7 +14,7 @@ import kotlin.reflect.KClass
 private typealias Handler = suspend (MinecraftPacket) -> Unit
 private typealias DirectionalHandler = suspend (MinecraftPacket, PacketDirection) -> Unit
 
-public open class PacketEventDispatcher {
+public abstract class PacketEventDispatcher {
     @Volatile
     @PublishedApi
     internal var receiveHandlers: Map<KClass<out MinecraftPacket>, List<Handler>> = emptyMap()

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/event/InternalPacketDispatcher.kt

@@ -1,96 +0,0 @@
-/*
- * Copyright © 2026 RTAkland
- * Author: RTAkland
- * Date: 2026/9/5
- */
-
-
-package cn.rtast.libmc.protocol.event
-
-import cn.rtast.libmc.packet.MinecraftPacket
-import cn.rtast.libmc.protocol.client.MinecraftClient
-import cn.rtast.libmc.protocol.crypto.minecraftServerIdHash
-import cn.rtast.libmc.protocol.crypto.rsaEncrypt
-import cn.rtast.libmc.protocol.packet.configuration.clientbound.*
-import cn.rtast.libmc.protocol.packet.configuration.serverbound.*
-import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundDisconnectLoginPacket
-import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundHelloPacket
-import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundLoginSuccessPacket
-import cn.rtast.libmc.protocol.packet.login.clientbound.ClientboundSetCompressionPacket
-import cn.rtast.libmc.protocol.packet.login.serverbound.ServerboundKeyPacket
-import cn.rtast.libmc.protocol.packet.login.serverbound.ServerboundLoginAcknowledgedPacket
-import cn.rtast.libmc.protocol.packet.play.clientbound.ClientboundDisconnectPlayPacket
-import cn.rtast.libmc.protocol.packet.play.clientbound.ClientboundKeepAlivePlayPacket
-import cn.rtast.libmc.protocol.packet.play.clientbound.ClientboundPingPacket
-import cn.rtast.libmc.protocol.packet.play.clientbound.ClientboundStartConfigurationPacket
-import cn.rtast.libmc.protocol.packet.play.serverbound.ServerboundConfigurationAcknowledgedPacket
-import cn.rtast.libmc.protocol.packet.play.serverbound.ServerboundKeepAlivePlayPacket
-import cn.rtast.libmc.protocol.packet.play.serverbound.ServerboundPongPlayPacket
-import cn.rtast.libmc.protocol.protocol.state.ProtocolState
-import cn.rtast.libmc.protocol.util.generateRandom16Bytes
-
-/**
- * Internal simple state machine trigger,
- * Auto respond packets the server needed.
- * Only including `Handshake`, `Login` and `Configuration` State
- */
-public class InternalPacketDispatcher(private val client: MinecraftClient) {
-    public suspend fun handleIncomingPackets(packet: MinecraftPacket) {
-        when (packet) {
-            // login
-            is ClientboundDisconnectLoginPacket -> client.close()
-            is ClientboundSetCompressionPacket -> client.networkChannel.setCompression(packet.threshold)
-            is ClientboundLoginSuccessPacket -> {
-                client.networkChannel.sendPacket(ServerboundLoginAcknowledgedPacket)
-                client.stateMachine.transitionTo(ProtocolState.CONFIGURATION)
-            }
-
-            is ClientboundHelloPacket -> {
-                val sharedSecret = generateRandom16Bytes()
-                if (client.isOnlineMode) {
-                    val serverHash = minecraftServerIdHash(packet.serverId, sharedSecret, packet.publicKey)
-                    client.protocolContext.authProvider!!.joinServer(
-                        "https://sessionserver.mojang.com/session/minecraft/join",
-                        client.accessToken!!,
-                        client.uuid.toString().replace("-", ""),
-                        serverHash
-                    )
-                }
-                val encryptedSecret = rsaEncrypt(packet.publicKey, sharedSecret)
-                val encryptedVerifyToken = rsaEncrypt(packet.publicKey, packet.verifyToken)
-                client.networkChannel.sendPacket(ServerboundKeyPacket(encryptedSecret, encryptedVerifyToken))
-                client.networkChannel.session.enableEncryption(sharedSecret)
-            }
-
-            // configuration
-            ClientboundFinishConfigurationPacket -> {
-                client.networkChannel.sendPacket(ServerboundAckFinishConfigurationPacket)
-                client.stateMachine.transitionTo(ProtocolState.PLAY)
-            }
-
-            is ClientboundKeepAliveConfigurationPacket -> client.networkChannel.sendPacket(
-                ServerboundKeepAliveConfigurationPacket(packet.id)
-            )
-
-            is ClientboundPingConfigurationPacket -> client.networkChannel.sendPacket(
-                ServerboundPongConfigurationPacket(packet.id)
-            )
-
-            is ClientboundSelectKnownPacksPacket -> client.networkChannel.sendPacket(
-                ServerboundSelectKnownPacksPacket(emptyList())
-            )  // TODO empty resource packs list
-            is ClientboundCodeOfConductPacket -> client.networkChannel.sendPacket(ServerboundAcceptCodeOfConductPacket)
-
-            // play
-            is ClientboundDisconnectPlayPacket -> client.close()
-            is ClientboundKeepAlivePlayPacket -> client.networkChannel.sendPacket(ServerboundKeepAlivePlayPacket(id = packet.id))
-            is ClientboundPingPacket -> client.networkChannel.sendPacket(ServerboundPongPlayPacket(packet.id))
-            ClientboundStartConfigurationPacket -> {
-                client.networkChannel.sendPacket(ServerboundConfigurationAcknowledgedPacket)
-                client.stateMachine.transitionTo(ProtocolState.CONFIGURATION)
-            }
-
-            else -> {}
-        }
-    }
-}

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/network/NetworkChannel.kt

@@ -14,7 +14,7 @@ import cn.rtast.libmc.packet.writeBuffer
 import cn.rtast.libmc.primitives.readVarInt
 import cn.rtast.libmc.primitives.writeVarInt
 import cn.rtast.libmc.protocol.client.ClientStateMachine
-import cn.rtast.libmc.protocol.event.PacketEventDispatcher
+import cn.rtast.libmc.protocol.client.PacketEventDispatcher
 import cn.rtast.libmc.protocol.protocol.GamePacketsProtocolCodec.clientboundGameProtocols
 import cn.rtast.libmc.protocol.protocol.GamePacketsProtocolCodec.serverboundGameProtocols
 import cn.rtast.libmc.zlibCompress

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/packet/play/clientbound/ClientboundSetEntityVelocityPacket.kt

@@ -11,10 +11,10 @@ import cn.rtast.libmc.network.BytesBuffer
 import cn.rtast.libmc.packet.PacketCodec
 import cn.rtast.libmc.packet.MinecraftPacket
 import cn.rtast.libmc.primitives.readVarInt
-import cn.rtast.libmc.protocol.protocol.game.math.LpVec3
+import cn.rtast.libmc.protocol.protocol.game.math.LpVec3d
 import cn.rtast.libmc.protocol.protocol.game.math.readLpVec3
 
-public data class ClientboundSetEntityVelocityPacket(val entityId: Int, val velocity: LpVec3) : MinecraftPacket {
+public data class ClientboundSetEntityVelocityPacket(val entityId: Int, val velocity: LpVec3d) : MinecraftPacket {
     internal companion object Codec : PacketCodec<ClientboundSetEntityVelocityPacket> {
         override fun encode(buffer: BytesBuffer, value: ClientboundSetEntityVelocityPacket) {}
         override fun decode(buffer: BytesBuffer): ClientboundSetEntityVelocityPacket {

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/packet/play/clientbound/ClientboundSpawnEntityPacket.kt

@@ -13,7 +13,7 @@ import cn.rtast.libmc.packet.PacketCodec
 import cn.rtast.libmc.primitives.readUuid
 import cn.rtast.libmc.primitives.readVarInt
 import cn.rtast.libmc.protocol.protocol.game.math.Angle
-import cn.rtast.libmc.protocol.protocol.game.math.LpVec3
+import cn.rtast.libmc.protocol.protocol.game.math.LpVec3d
 import cn.rtast.libmc.protocol.protocol.game.math.readAngle
 import cn.rtast.libmc.protocol.protocol.game.math.readLpVec3
 import kotlin.uuid.Uuid
@@ -28,7 +28,7 @@ public data class ClientboundSpawnEntityPacket(
     val x: Double,
     val y: Double,
     val z: Double,
-    val velocity: LpVec3,
+    val velocity: LpVec3d,
     val pitch: Angle,
     val yaw: Angle,
     val headYaw: Angle,

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/packet/play/serverbound/ServerboundInteractPacket.kt

@@ -11,14 +11,14 @@ import cn.rtast.libmc.network.BytesBuffer
 import cn.rtast.libmc.packet.PacketCodec
 import cn.rtast.libmc.packet.MinecraftPacket
 import cn.rtast.libmc.primitives.writeVarInt
-import cn.rtast.libmc.protocol.protocol.game.math.LpVec3
+import cn.rtast.libmc.protocol.protocol.game.math.LpVec3d
 import cn.rtast.libmc.protocol.protocol.game.math.writeLpVec3
 import cn.rtast.libmc.protocol.protocol.game.player.Hand
 
 public data class ServerboundInteractPacket(
     val entityId: Int,
     val hand: Hand,
-    val targetOffset: LpVec3,
+    val targetOffset: LpVec3d,
     val isSneaking: Boolean,
 ) : MinecraftPacket {
     internal companion object Codec : PacketCodec<ServerboundInteractPacket> {

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/packet/play/serverbound/ServerboundSetPlayerPositionPacket.kt

@@ -8,22 +8,25 @@
 package cn.rtast.libmc.protocol.packet.play.serverbound
 
 import cn.rtast.libmc.network.BytesBuffer
-import cn.rtast.libmc.packet.PacketCodec
 import cn.rtast.libmc.packet.MinecraftPacket
-import cn.rtast.libmc.protocol.protocol.game.player.PlayerPositionFlag
+import cn.rtast.libmc.packet.PacketCodec
 
 public data class ServerboundSetPlayerPositionPacket(
     val x: Double,
     val feetY: Double,
     val z: Double,
-    val flags: PlayerPositionFlag,
+    val onGround: Boolean,
+    val pushingAgainstWall: Boolean = false,
 ) : MinecraftPacket {
     internal companion object Codec : PacketCodec<ServerboundSetPlayerPositionPacket> {
         override fun encode(buffer: BytesBuffer, value: ServerboundSetPlayerPositionPacket) {
             buffer.writeDouble(value.x)
             buffer.writeDouble(value.feetY)
             buffer.writeDouble(value.z)
-            buffer.writeByte(value.flags.flag)
+            var flags = 0
+            if (value.onGround) flags = flags or 0x01
+            if (value.pushingAgainstWall) flags = flags or 0x02
+            buffer.writeByte(flags.toByte())
         }
 
         override fun decode(buffer: BytesBuffer): ServerboundSetPlayerPositionPacket =

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/protocol/game/math/LpVec3d.kt

@@ -7,7 +7,6 @@
 
 package cn.rtast.libmc.protocol.protocol.game.math
 
-import cn.rtast.libmc.network.ByteOrder
 import cn.rtast.libmc.network.BytesBuffer
 import cn.rtast.libmc.primitives.readVarInt
 import cn.rtast.libmc.primitives.writeVarInt
@@ -17,14 +16,10 @@ import kotlin.math.max
 import kotlin.math.min
 
 // ref: https://minecraft.wiki/w/Java_Edition_protocol/Data_types#LpVec3
-public data class LpVec3(
-    val x: Double,
-    val y: Double,
-    val z: Double,
-) {
+public data class LpVec3d(var x: Double, var y: Double, var z: Double) {
     @Suppress("UNUSED")
     public companion object {
-        public val ZERO: LpVec3 = LpVec3(0.0, 0.0, 0.0)
+        public val ZERO: LpVec3d = LpVec3d(0.0, 0.0, 0.0)
 
         private const val MAX_QUANTIZED_VALUE = 32766.0
         private const val CONTINUATION_FLAG = 0x04L
@@ -39,23 +34,23 @@ public data class LpVec3(
 }
 
 // ref: https://minecraft.wiki/w/Java_Edition_protocol/Data_types#LpVec3
-internal fun BytesBuffer.readLpVec3(): LpVec3 {
+internal fun BytesBuffer.readLpVec3(): LpVec3d {
     val byte1 = readByte().toInt() and 0xFF
-    if (byte1 == 0) return LpVec3.ZERO
+    if (byte1 == 0) return LpVec3d.ZERO
     val byte2 = readByte().toInt() and 0xFF
     val bytes3To6 = readInt().toLong() and 0xFFFFFFFFL
     val packed = (bytes3To6 shl 16) or (byte2.toLong() shl 8) or byte1.toLong()
     var scaleFactor = byte1.toLong() and 0x03L
     if ((byte1.toLong() and 0x04L) != 0L) scaleFactor = scaleFactor or (readVarInt().toLong() shl 2)
     val scale = scaleFactor.toDouble()
-    val x = LpVec3.unpack(packed shr 3) * scale
-    val y = LpVec3.unpack(packed shr 18) * scale
-    val z = LpVec3.unpack(packed shr 33) * scale
-    return LpVec3(x, y, z)
+    val x = LpVec3d.unpack(packed shr 3) * scale
+    val y = LpVec3d.unpack(packed shr 18) * scale
+    val z = LpVec3d.unpack(packed shr 33) * scale
+    return LpVec3d(x, y, z)
 }
 
 // ref: https://minecraft.wiki/w/Java_Edition_protocol/Data_types#LpVec3
-internal fun BytesBuffer.writeLpVec3(vec3: LpVec3) {
+internal fun BytesBuffer.writeLpVec3(vec3: LpVec3d) {
     val maxCoordinate = max(abs(vec3.x), max(abs(vec3.y), abs(vec3.z)))
     if (maxCoordinate.isNaN() || maxCoordinate < 1.0 / 32766.0) {
         writeByte(0x00)
@@ -64,9 +59,9 @@ internal fun BytesBuffer.writeLpVec3(vec3: LpVec3) {
     val scaleFactor = ceil(maxCoordinate).toLong()
     val needContinuation = (scaleFactor and 0x03L) != scaleFactor
     val packedScale = if (needContinuation) ((scaleFactor and 0x03L) or 0x04L) else scaleFactor
-    val packedX = LpVec3.pack((vec3.x / scaleFactor.toDouble()).toLong()) shl 3
-    val packedY = LpVec3.pack((vec3.y / scaleFactor.toDouble()).toLong()) shl 18
-    val packedZ = LpVec3.pack((vec3.z / scaleFactor.toDouble()).toLong()) shl 33
+    val packedX = LpVec3d.pack((vec3.x / scaleFactor.toDouble()).toLong()) shl 3
+    val packedY = LpVec3d.pack((vec3.y / scaleFactor.toDouble()).toLong()) shl 18
+    val packedZ = LpVec3d.pack((vec3.z / scaleFactor.toDouble()).toLong()) shl 33
     val packed = packedZ or packedY or packedX or packedScale
     writeByte(packed.toByte())
     writeByte((packed shr 8).toByte())

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/protocol/game/math/Vec3d.kt

@@ -9,7 +9,7 @@ package cn.rtast.libmc.protocol.protocol.game.math
 
 import cn.rtast.libmc.network.BytesBuffer
 
-public data class Vec3d(val x: Double, val y: Double, val z: Double) {
+public data class Vec3d(var x: Double, var y: Double, var z: Double) {
     public companion object {
         public val ZERO: Vec3d = Vec3d(0.0, 0.0, 0.0)
     }

libmc-protocol/src/commonMain/kotlin/cn/rtast/libmc/protocol/protocol/game/player/InteractType.kt

@@ -7,10 +7,10 @@
 
 package cn.rtast.libmc.protocol.protocol.game.player
 
-import cn.rtast.libmc.protocol.protocol.game.math.LpVec3
+import cn.rtast.libmc.protocol.protocol.game.math.LpVec3d
 
 public sealed class InteractType(public val id: Int) {
     public data class Interact(val hand: Hand) : InteractType(0)
     public data object Attack : InteractType(1)
-    public data class InteractAt(val targetOffset: LpVec3, val hand: Hand) : InteractType(2)
+    public data class InteractAt(val targetOffset: LpVec3d, val hand: Hand) : InteractType(2)
 }