From a470c3a0ea90e644f127440a9134fe3d52bf7c49 Mon Sep 17 00:00:00 2001
From: Kamay Xutax <admin@xutaxkamay.com>
Date: Fri, 12 Jul 2024 15:15:40 +0200
Subject: [PATCH] Fixed lag compensation with low fps

---
 game/client/in_main.cpp                |  2 +-
 game/server/player_lagcompensation.cpp | 67 +++++---------------------
 game/shared/usercmd.cpp                |  6 +--
 game/shared/usercmd.h                  |  5 +-
 4 files changed, 20 insertions(+), 60 deletions(-)

diff --git a/game/client/in_main.cpp b/game/client/in_main.cpp
index 858208301b..766107d9e5 100644
--- a/game/client/in_main.cpp
+++ b/game/client/in_main.cpp
@@ -1328,7 +1328,7 @@ void CInput::CreateMove ( int sequence_number, float input_sample_frametime, boo
         }
 
         cmd->has_animation[pBasePlayer->index] = true;
-        cmd->animationdata[pBasePlayer->index].m_flAnimTime = pBasePlayer->m_flAnimTime;
+        cmd->animationdata[pBasePlayer->index].m_flUninterpolatedSimulationTime = pBasePlayer->m_flSimulationTime;
     }
 
 	pVerified->m_cmd = *cmd;
diff --git a/game/server/player_lagcompensation.cpp b/game/server/player_lagcompensation.cpp
index 35ad65d88e..f8b3cc75b5 100644
--- a/game/server/player_lagcompensation.cpp
+++ b/game/server/player_lagcompensation.cpp
@@ -388,33 +388,6 @@ void CLagCompensationManager::StartLagCompensation( CBasePlayer *player, CUserCm
 	}
 }
 
-template <class T>
-inline T LoopingLerp( float flPercent, T flFrom, T flTo )
-{
-	T s = flTo * flPercent + flFrom * (1.0f - flPercent);
-	return s;
-}
-
-template <>
-inline float LoopingLerp( float flPercent, float flFrom, float flTo )
-{
-	if ( fabs( flTo - flFrom ) >= 0.5f )
-	{
-		if (flFrom < flTo)
-			flFrom += 1.0f;
-		else
-			flTo += 1.0f;
-	}
-
-	float s = flTo * flPercent + flFrom * (1.0f - flPercent);
-
-	s = s - (int)(s);
-	if (s < 0.0f)
-		s = s + 1.0f;
-
-	return s;
-}
-
 void CLagCompensationManager::BacktrackPlayer( CBasePlayer *pPlayer, CUserCmd *cmd )
 {
 	Vector org;
@@ -440,8 +413,10 @@ void CLagCompensationManager::BacktrackPlayer( CBasePlayer *pPlayer, CUserCmd *c
 
 	LagRecord *prevRecordSim = NULL;
 	LagRecord *recordSim = NULL;
+	LagRecord *recordAnim = NULL;
 
-	Vector prevOrg = pPlayer->GetLocalOrigin();
+    Vector prevOrg = pPlayer->GetLocalOrigin();
+    bool foundAnimationData = false;
 	
 	// Walk context looking for any invalidating event
 	while( trackSim->IsValidIndex(currSim) )
@@ -450,7 +425,14 @@ void CLagCompensationManager::BacktrackPlayer( CBasePlayer *pPlayer, CUserCmd *c
 		prevRecordSim = recordSim;
 
 		// get next record
-		recordSim = &trackSim->Element( currSim );
+        recordSim = &trackSim->Element(currSim);
+
+        if (recordSim->m_flSimulationTime
+            <= animationData->m_flUninterpolatedSimulationTime and !foundAnimationData)
+        {
+            recordAnim = recordSim;
+            foundAnimationData = true;
+		}
 
 		if ( !(recordSim->m_fFlags & LC_ALIVE) )
 		{
@@ -470,31 +452,6 @@ void CLagCompensationManager::BacktrackPlayer( CBasePlayer *pPlayer, CUserCmd *c
 		currSim = trackSim->Next( currSim );
 	}
 
-    intp currAnim = trackAnim->Head();
-	LagRecord *recordAnim = NULL;
-
-	// Walk context looking for any invalidating event
-	while( trackAnim->IsValidIndex(currAnim) )
-	{
-		// get next record
-		recordAnim = &trackAnim->Element( currAnim );
-
-		if ( !(recordAnim->m_fFlags & LC_ALIVE) )
-		{
-			// player most be alive, lost track
-			return;
-		}
-
-		// TODO: do proper teleportation checks.
-
-		// did we find a context smaller than target time ?
-		if ( recordAnim->m_flAnimTime <= animationData->m_flAnimTime )
-			break; // hurra, stop
-
-		// go one step back
-		currAnim = trackAnim->Next( currAnim );
-	}
-
 	Assert( recordAnim );
 	Assert( recordSim );
 
@@ -706,7 +663,7 @@ void CLagCompensationManager::BacktrackPlayer( CBasePlayer *pPlayer, CUserCmd *c
 
 	// Set lag compensated player's times
 	pPlayer->SetSimulationTime(flTargetSimulationTime);
-	pPlayer->SetAnimTime(animationData->m_flAnimTime);
+	// pPlayer->SetAnimTime(animationData->m_flAnimTime);
 
 	if ( sv_lagflushbonecache.GetBool() )
         pPlayer->InvalidateBoneCache();
diff --git a/game/shared/usercmd.cpp b/game/shared/usercmd.cpp
index 66725faa12..d9ad6b731d 100644
--- a/game/shared/usercmd.cpp
+++ b/game/shared/usercmd.cpp
@@ -204,10 +204,10 @@ void WriteUsercmd( bf_write *buf, const CUserCmd *to, const CUserCmd *from )
             continue;
 		}
 
-		if (to->animationdata[i].m_flAnimTime != from->animationdata[i].m_flAnimTime)
+		if (to->animationdata[i].m_flUninterpolatedSimulationTime != from->animationdata[i].m_flUninterpolatedSimulationTime)
 		{
 			buf->WriteOneBit( 1 );
-			buf->WriteFloat( to->animationdata[i].m_flAnimTime );
+			buf->WriteFloat( to->animationdata[i].m_flUninterpolatedSimulationTime );
 		}
 		else
 		{
@@ -360,7 +360,7 @@ void ReadUsercmd( bf_read *buf, CUserCmd *move, CUserCmd *from )
 
 		if (buf->ReadOneBit())
 		{
-			move->animationdata[i].m_flAnimTime = buf->ReadFloat();
+			move->animationdata[i].m_flUninterpolatedSimulationTime = buf->ReadFloat();
         }
 	}
 
diff --git a/game/shared/usercmd.h b/game/shared/usercmd.h
index d370318d60..28ed6b92d5 100644
--- a/game/shared/usercmd.h
+++ b/game/shared/usercmd.h
@@ -53,7 +53,10 @@ struct LayerRecord
 
 struct ClientSideAnimationData
 {
-	float					m_flAnimTime;   
+    // TODO_ENHANCED:
+    // For now we send the last received update for animations.
+    // anim time is unreliable on low fps.
+	float					m_flUninterpolatedSimulationTime;   
 };
 
 class CEntityGroundContact