fix: incorrect velocity when standing still

pkg/demoinfocs/common/player.go

@@ -15,25 +15,25 @@ import (
 type Player struct {
 	demoInfoProvider demoInfoProvider // provider for demo info such as tick-rate or current tick
 
-	SteamID64         uint64             // 64-bit representation of the user's Steam ID. See https://developer.valvesoftware.com/wiki/SteamID
-	LastAlivePosition r3.Vector          // The location where the player was last alive. Should be equal to Position if the player is still alive.
-	UserID            int                // Mostly used in game-events to address this player
-	Name              string             // Steam / in-game user name
-	Inventory         map[int]*Equipment // All weapons / equipment the player is currently carrying. See also Weapons().
-	AmmoLeft          [32]int            // Ammo left for special weapons (e.g. grenades), index corresponds Equipment.AmmoType
-	EntityID          int                // Usually the same as Entity.ID() but may be different between player death and re-spawn.
-	Entity            st.Entity          // May be nil between player-death and re-spawn
-	FlashDuration     float32            // Blindness duration from the flashbang currently affecting the player (seconds)
-	FlashTick         int                // In-game tick at which the player was last flashed
-	TeamState         *TeamState         // When keeping the reference make sure you notice when the player changes teams
-	Team              Team               // Team identifier for the player (e.g. TeamTerrorists or TeamCounterTerrorists).
-	IsBot             bool               // True if this is a bot-entity. See also IsControllingBot and ControlledBot().
-	IsConnected       bool
-	IsDefusing        bool
-	IsPlanting        bool
-	IsReloading       bool
-	IsUnknown         bool        // Used to identify unknown/broken players. see https://github.com/markus-wa/demoinfocs-golang/issues/162
-	LastPositions     []r3.Vector // CS2 only, used to compute velocity as it's not networked in CS2 demos
+	SteamID64             uint64             // 64-bit representation of the user's Steam ID. See https://developer.valvesoftware.com/wiki/SteamID
+	LastAlivePosition     r3.Vector          // The location where the player was last alive. Should be equal to Position if the player is still alive.
+	UserID                int                // Mostly used in game-events to address this player
+	Name                  string             // Steam / in-game user name
+	Inventory             map[int]*Equipment // All weapons / equipment the player is currently carrying. See also Weapons().
+	AmmoLeft              [32]int            // Ammo left for special weapons (e.g. grenades), index corresponds Equipment.AmmoType
+	EntityID              int                // Usually the same as Entity.ID() but may be different between player death and re-spawn.
+	Entity                st.Entity          // May be nil between player-death and re-spawn
+	FlashDuration         float32            // Blindness duration from the flashbang currently affecting the player (seconds)
+	FlashTick             int                // In-game tick at which the player was last flashed
+	TeamState             *TeamState         // When keeping the reference make sure you notice when the player changes teams
+	Team                  Team               // Team identifier for the player (e.g. TeamTerrorists or TeamCounterTerrorists).
+	IsBot                 bool               // True if this is a bot-entity. See also IsControllingBot and ControlledBot().
+	IsConnected           bool
+	IsDefusing            bool
+	IsPlanting            bool
+	IsReloading           bool
+	IsUnknown             bool      // Used to identify unknown/broken players. see https://github.com/markus-wa/demoinfocs-golang/issues/162
+	PreviousFramePosition r3.Vector // CS2 only, used to compute velocity as it's not networked in CS2 demos
 }
 
 func (p *Player) PlayerPawnEntity() st.Entity {
@@ -522,12 +522,8 @@ func (p *Player) PositionEyes() r3.Vector {
 // Velocity returns the player's velocity.
 func (p *Player) Velocity() r3.Vector {
 	if p.demoInfoProvider.IsSource2() {
-		if !p.IsAlive() || len(p.LastPositions) != 2 {
-			return r3.Vector{}
-		}
-
 		t := 64.0
-		diff := p.LastPositions[1].Sub(p.LastPositions[0])
+		diff := p.Position().Sub(p.PreviousFramePosition)
 
 		return r3.Vector{
 			X: diff.X * t,
@@ -813,9 +809,10 @@ type demoInfoProvider interface {
 // Intended for internal use only.
 func NewPlayer(demoInfoProvider demoInfoProvider) *Player {
 	return &Player{
-		Inventory:         make(map[int]*Equipment),
-		demoInfoProvider:  demoInfoProvider,
-		LastAlivePosition: r3.Vector{},
+		Inventory:             make(map[int]*Equipment),
+		demoInfoProvider:      demoInfoProvider,
+		LastAlivePosition:     r3.Vector{},
+		PreviousFramePosition: r3.Vector{},
 	}
 }
 

pkg/demoinfocs/common/player_test.go

@@ -432,9 +432,10 @@ func createPlayerForVelocityTest() *Player {
 	controllerEntity := entityWithProperties([]fakeProp{
 		{propName: "m_hPlayerPawn", value: st.PropertyValue{Any: uint64(1), S2: true}},
 	})
-	pawnEntity := entityWithProperties([]fakeProp{
-		{propName: "m_iHealth", value: st.PropertyValue{Any: int32(100), S2: true}},
-	})
+	pawnEntity := new(stfake.Entity)
+	position := r3.Vector{X: 20, Y: 300, Z: 100}
+
+	pawnEntity.On("Position").Return(position)
 
 	pl := &Player{
 		Entity: controllerEntity,
@@ -453,14 +454,15 @@ func createPlayerForVelocityTest() *Player {
 
 func TestPlayer_VelocityS2(t *testing.T) {
 	pl := createPlayerForVelocityTest()
-	pl.LastPositions = []r3.Vector{{X: 10, Y: 200, Z: 50}, {X: 20, Y: 300, Z: 100}}
+	pl.PreviousFramePosition = r3.Vector{X: 10, Y: 200, Z: 50}
 
 	expected := r3.Vector{X: 640, Y: 6400, Z: 3200}
 	assert.Equal(t, expected, pl.Velocity())
 }
 
-func TestPlayer_VelocityS2WithoutPositions(t *testing.T) {
+func TestPlayer_VelocityDidNotChangeS2(t *testing.T) {
 	pl := createPlayerForVelocityTest()
+	pl.PreviousFramePosition = r3.Vector{X: 20, Y: 300, Z: 100}
 
 	expected := r3.Vector{X: 0, Y: 0, Z: 0}
 	assert.Equal(t, expected, pl.Velocity())

pkg/demoinfocs/datatables.go

@@ -569,12 +569,6 @@ func (p *parser) bindNewPlayerPawnS2(pawnEntity st.Entity) {
 		}
 		if pl.IsAlive() {
 			pl.LastAlivePosition = pos
-			pl.LastPositions = append(pl.LastPositions, pos)
-			if len(pl.LastPositions) > 2 {
-				pl.LastPositions = pl.LastPositions[1:]
-			}
-		} else {
-			pl.LastPositions = nil
 		}
 	})
 

pkg/demoinfocs/parsing.go

@@ -525,6 +525,10 @@ func (p *parser) handleFrameParsed(*frameParsedTokenType) {
 
 	p.currentFrame++
 	p.eventDispatcher.Dispatch(events.FrameDone{})
+
+	if p.isSource2() {
+		p.updatePlayersPreviousFramePosition()
+	}
 }
 
 // CS2 demos playback info are available in the CDemoFileInfo message that should be parsed at the end of the demo.

pkg/demoinfocs/s2_commands.go

@@ -378,3 +378,9 @@ func (p *parser) handleDemoFileHeader(msg *msgs2.CDemoFileHeader) {
 	p.header.MapName = msg.GetMapName()
 	p.header.NetworkProtocol = int(msg.GetNetworkProtocol())
 }
+
+func (p *parser) updatePlayersPreviousFramePosition() {
+	for _, player := range p.GameState().Participants().Playing() {
+		player.PreviousFramePosition = player.Position()
+	}
+}