Do not send status bar if the target unable to visible through fog density

regamedll/dlls/player.cpp

@@ -7858,6 +7858,22 @@ void CBasePlayer::UpdateStatusBar()
 			CBaseEntity *pEntity = CBaseEntity::Instance(tr.pHit);
 			bool isVisiblePlayer = ((TheBots == nullptr || !TheBots->IsLineBlockedBySmoke(&pev->origin, &pEntity->pev->origin)) && pEntity->Classify() == CLASS_PLAYER);
 
+#ifdef REGAMEDLL_FIXES
+			if (g_FogParameters.density > 0)
+			{
+				// Estimation of the max distance to which an entity is visible,
+				// taking into account the fog density and the visibility factor
+				const float flVisibilityFogFactor = 2.0f;
+				float flDistance                  = (pev->origin - pEntity->pev->origin).Length();
+				float flMaxVisibleDistance        = flVisibilityFogFactor / g_FogParameters.density;
+
+				// Check if the distance between the player's position and the entity
+				// exceeds the max visible distance. If so, the entity is not visible
+				if (flDistance > flMaxVisibleDistance)
+					isVisiblePlayer = false;
+			}
+#endif
+
 			if (gpGlobals->time >= m_blindUntilTime && isVisiblePlayer)
 			{
 				CBasePlayer *pTarget = (CBasePlayer *)pEntity;

regamedll/dlls/triggers.cpp

@@ -2469,6 +2469,8 @@ void CWeather::Spawn()
 	InitTrigger();
 }
 
+FogParameters g_FogParameters;
+
 void CClientFog::KeyValue(KeyValueData *pkvd)
 {
 #if 0
@@ -2505,6 +2507,28 @@ void CClientFog::Spawn()
 	pev->solid = SOLID_NOT;				// Remove model & collisions
 	pev->renderamt = 0;				// The engine won't draw this model if this is set to 0 and blending is on
 	pev->rendermode = kRenderTransTexture;
+
+	g_FogParameters.density = m_fDensity;
+	g_FogParameters.r       = clamp(int(pev->rendercolor[0]), 0, 255);
+	g_FogParameters.g       = clamp(int(pev->rendercolor[1]), 0, 255);
+	g_FogParameters.b       = clamp(int(pev->rendercolor[2]), 0, 255);
+}
+
+void CClientFog::OnDestroy()
+{
+	g_FogParameters.density = 0;
+
+#ifdef REGAMEDLL_FIXES
+	if (!g_bServerActive)
+		return; // server isn't active or changes map
+
+	MESSAGE_BEGIN(MSG_ALL, gmsgFog);
+		WRITE_BYTE(0);
+		WRITE_BYTE(0);
+		WRITE_BYTE(0);
+		WRITE_LONG(0); // a fog density of 0 suggests fog is disabled
+	MESSAGE_END();
+#endif
 }
 
 LINK_ENTITY_TO_CLASS(env_fog, CClientFog, CCSClientFog)

regamedll/dlls/triggers.h

@@ -538,6 +538,7 @@ class CClientFog: public CBaseEntity
 public:
 	virtual void Spawn();
 	virtual void KeyValue(KeyValueData *pkvd);
+	virtual void OnDestroy();
 
 public:
 	int m_iStartDist;
@@ -545,6 +546,25 @@ public:
 	float m_fDensity;
 };
 
+struct FogParameters
+{
+	FogParameters() :
+		r(0), g(0), b(0), density(0)
+	{
+	}
+
+	void Clear()
+	{
+		r = g = b = 0;
+		density   = 0;
+	}
+
+	int r, g, b;
+	float density;
+};
+
+extern FogParameters g_FogParameters;
+
 void PlayCDTrack(edict_t *pClient, int iTrack);
 int BuildChangeList(LEVELLIST *pLevelList, int maxList);
 void NextLevel();

regamedll/dlls/world.cpp

@@ -279,6 +279,7 @@ void CWorld::Precache()
 	g_pLastSpawn = nullptr;
 	g_pLastCTSpawn = nullptr;
 	g_pLastTerroristSpawn = nullptr;
+	g_FogParameters.Clear();
 
 	CVAR_SET_STRING("sv_gravity", "800");
 	CVAR_SET_STRING("sv_maxspeed", "900");