add env_fog

The hackiest solution for fog ever. It works using multiple overlapping spheres surrounding the player with different scales and transparencies.

Scale is controlled by animations, and color by submodels which map to a single pixel in a swappable texture. An offset is applied so that the model can be made full bright with the EF_BRIGHTLIGHT effect, without the light being visible.

It looks good with 64 layers, but that's too much entity data to send. These can't be attached to players with aiment because then the animations break. So, it uses 16 layers for now. It looks very retro, even for HL.

Transparent entities are bugged with fog. Anything in the fog volume is made invisible unless changing rendermode back to normal. This will happen for everything except beams. Sprites mostly look correct. Windows will suddenly become solid sometimes, especially if multiple are tied together to form a large bounding box.

dlls/CBaseEntity.h

@@ -176,6 +176,8 @@ class EXPORT CBaseEntity
 	virtual BOOL	IsNetClient(void) { return FALSE; }
 	virtual BOOL	IsBreakable(void) { return FALSE; }
 	virtual BOOL	IsMachine(void) { return FALSE; };
+	virtual BOOL	IsWeather(void) { return FALSE; };
+	virtual BOOL	IsBeam(void) { return FALSE; };
 	virtual const char* TeamID(void) { return ""; }
 	virtual const char* DisplayName() { return STRING(pev->classname); }
 	virtual const char* GetDeathNoticeWeapon() { return STRING(pev->classname); };
@@ -387,10 +389,13 @@ class EXPORT CBaseEntity
 	InventoryRules	m_inventoryRules;
 	bool m_isFadingOut; // is a corpse fading out
 
+	Vector m_fakeFollowOffset; // offset applied to player origin when entity is fake following
+
 	uint32_t m_pasPlayers; // players in the audible set of this entity (invalid for invisible ents)
 	uint32_t m_pvsPlayers; // players in the visible set of this entity (invalid for invisible ents)
 	uint32_t m_netPlayers; // players this entity has been networked to (AddToFullPack returned 1)
 	uint32_t m_hidePlayers; // players this entity will be hidden from (AddToFullPack)
+	uint32_t m_fakeFollow; // players this entity will attach to, ignoring true origin (AddToFullPack)
 
 private:
 	bool TestInventoryRules(CBaseMonster* mon, std::unordered_set<CItemInventory*>& usedItems, const char** errorMsg);

dlls/CMakeLists.txt

@@ -164,6 +164,7 @@ set(ENV_SRC
 	env/CSprayCan.cpp
 	env/CSprite.cpp
 	env/CTestEffect.cpp
+	env/fog_colors.cpp
 )
 
 set(ITEM_HDR

dlls/env/CBeam.h

@@ -25,6 +25,7 @@ class CBeam : public CBaseEntity
 		return (CBaseEntity::ObjectCaps() & ~FCAP_ACROSS_TRANSITION) | flags;
 	}
 	virtual const char* DisplayName() { return "Laser"; }
+	virtual BOOL	IsBeam(void) { return TRUE; };
 
 	void EXPORT TriggerTouch(CBaseEntity* pOther);