From b145cc82f5ca62e446b9a967afff619f599f29e4 Mon Sep 17 00:00:00 2001
From: ricardoofnl <raditiyaeltamricardo@outlook.de>
Date: Sat, 5 Sep 2026 09:31:26 +0700
Subject: [PATCH] [saco] Implement/match `FUNC_10015C90`, the trailer sync
 handler; the 0.5 gate is a `<=` chain and the 6.0/3.0 snap gate a `>` chain

---
 saco/game/vehicle.h       |  3 ++
 saco/net/remoteplayer.cpp | 61 +++++++++++++++++++++++++++++++++++++++
 saco/net/remoteplayer.h   | 10 +++++++
 3 files changed, 74 insertions(+)

diff --git a/saco/game/vehicle.h b/saco/game/vehicle.h
index 2cef674..7df50a2 100644
--- a/saco/game/vehicle.h
+++ b/saco/game/vehicle.h
@@ -94,6 +94,9 @@ public:
 	void	FUNC_100B8150(char *szText); // .text:100B8150
 	void	FUNC_100B7C10(); // .text:100B7C10
 	void	FUNC_100B7C80(int a1); // .text:100B7C80
+	CVehicle *FUNC_100B7C90(); // .text:100B7C90
+	BOOL	FUNC_100B7D70(); // .text:100B7D70
+	BOOL	FUNC_100B7DD0(); // .text:100B7DD0
 
 	BOOL	FUNC_100B7460(); // .text:100B7460
 	BOOL	FUNC_100B7E00(); // .text:100B7E00
diff --git a/saco/net/remoteplayer.cpp b/saco/net/remoteplayer.cpp
index c595f9d..2cc60a8 100644
--- a/saco/net/remoteplayer.cpp
+++ b/saco/net/remoteplayer.cpp
@@ -41,6 +41,8 @@ typedef char CRemotePlayer_offsets[(
 typedef char CNetPlayer_offsets[(offsetof(CNetPlayer, m_PlayerName) == 0x14) ? 1 : -1];
 typedef char BULLET_SYNC_offsets[(offsetof(BULLET_SYNC_DATA, byteWeaponID) == 0x27 &&
 	sizeof(BULLET_SYNC_DATA) == 0x28) ? 1 : -1];
+typedef char TRAILER_SYNC_offsets[(offsetof(TRAILER_SYNC_DATA, vecTurnSpeed) == 0x2A &&
+	sizeof(TRAILER_SYNC_DATA) == 0x36) ? 1 : -1];
 typedef char struc_41_offsets[(offsetof(struc_41, field_30) == 0x30) ? 1 : -1];
 typedef char WEAPON_SLOT_offsets[(offsetof(WEAPON_SLOT_TYPE, field_8) == 8 &&
 	sizeof(WEAPON_SLOT_TYPE) == 28) ? 1 : -1];
@@ -475,6 +477,65 @@ void CRemotePlayer::FUNC_10016370(BULLET_SYNC_DATA *pSync)
 
 //----------------------------------------------------
 
+void CRemotePlayer::FUNC_10015C90(TRAILER_SYNC_DATA *pTrailer)
+{
+	if(!pTrailer->TrailerID) return;
+	if(pTrailer->TrailerID == INVALID_VEHICLE_ID) return;
+
+	MATRIX4X4 mat;
+	VECTOR vecMove;
+
+	CVehicle *pTrailerVeh = (CVehicle *)pNetGame->GetVehiclePool()->GetAt(pTrailer->TrailerID);
+	CVehicle *pVehicle = field_1E1;
+	if(!pVehicle) return;
+	if(!pTrailerVeh) return;
+
+	if(!pTrailerVeh->FUNC_100B7D70() && !pVehicle->FUNC_100B7DD0()) return;
+
+	if(pVehicle->FUNC_100B7C90() != pTrailerVeh) {
+		pVehicle->FUNC_100B7C80((int)pTrailerVeh);
+		pVehicle->FUNC_100B7C10();
+	}
+
+	pTrailerVeh->GetMatrix(&mat);
+	FUNC_100B6A80(pTrailer->quat, &mat);
+
+	if(FloatOffset(pTrailer->vecPos.X, mat.pos.X) <= 0.5f &&
+		FloatOffset(pTrailer->vecPos.Y, mat.pos.Y) <= 0.5f &&
+		FloatOffset(pTrailer->vecPos.Z, mat.pos.Z) <= 0.5f) return;
+
+	if(FloatOffset(pTrailer->vecPos.X, mat.pos.X) > 6.0f ||
+		FloatOffset(pTrailer->vecPos.Y, mat.pos.Y) > 6.0f ||
+		FloatOffset(pTrailer->vecPos.Z, mat.pos.Z) > 3.0f) {
+		mat.pos.X = pTrailer->vecPos.X;
+		mat.pos.Y = pTrailer->vecPos.Y;
+		mat.pos.Z = pTrailer->vecPos.Z;
+		pTrailerVeh->SetMatrix(mat);
+		pTrailerVeh->SetMoveSpeedVector(pTrailer->vecMoveSpeed);
+		pTrailerVeh->SetTurnSpeedVector(pTrailer->vecTurnSpeed);
+		return;
+	}
+
+	pTrailerVeh->SetMatrix(mat);
+	pTrailerVeh->SetTurnSpeedVector(pTrailer->vecTurnSpeed);
+
+	vecMove.X = 0.0f;
+	vecMove.Y = 0.0f;
+	vecMove.Z = 0.0f;
+	pTrailerVeh->GetMoveSpeedVector(&vecMove);
+
+	if(FloatOffset(pTrailer->vecPos.X, mat.pos.X) > 0.05f)
+		vecMove.X = (pTrailer->vecPos.X - mat.pos.X) * 0.025f + vecMove.X;
+	if(FloatOffset(pTrailer->vecPos.Y, mat.pos.Y) > 0.05f)
+		vecMove.Y = (pTrailer->vecPos.Y - mat.pos.Y) * 0.025f + vecMove.Y;
+	if(FloatOffset(pTrailer->vecPos.Z, mat.pos.Z) > 0.05f)
+		vecMove.Z = (pTrailer->vecPos.Z - mat.pos.Z) * 0.025f + vecMove.Z;
+
+	pTrailerVeh->SetMoveSpeedVector(vecMove);
+}
+
+//----------------------------------------------------
+
 void CRemotePlayer::FUNC_10014950()
 {
 	if(!m_pPlayerPed) return;
diff --git a/saco/net/remoteplayer.h b/saco/net/remoteplayer.h
index f283163..b2352d4 100644
--- a/saco/net/remoteplayer.h
+++ b/saco/net/remoteplayer.h
@@ -3,6 +3,15 @@
 
 //----------------------------------------------------
 
+struct TRAILER_SYNC_DATA
+{
+	VEHICLEID	TrailerID;
+	VECTOR		vecPos;
+	float		quat[4];
+	VECTOR		vecMoveSpeed;
+	VECTOR		vecTurnSpeed;
+};
+
 // the bullet sync payload, 0x28 bytes on the wire
 struct BULLET_SYNC_DATA
 {
@@ -108,6 +117,7 @@ public:
 	void FUNC_10014C40(); // .text:10014C40
 	void FUNC_10016370(BULLET_SYNC_DATA *pSync); // .text:10016370
 	void FUNC_10014950(); // .text:10014950
+	void FUNC_10015C90(TRAILER_SYNC_DATA *pTrailer); // .text:10015C90
 	void FUNC_10014E60(); // .text:10014E60
 	void FUNC_10015460(); // .text:10015460
 	void FUNC_10015760(BYTE *pAim); // .text:10015760