Simulated Bullets

Preface

Basically, with simulated bullets, the aspects of physics are going to tried to be captured by simulating them in batch simulation code. So far the code is all server-side and is later expected to be client-side simulated with similar code.

Note:This code is a work in progress. Feel free to make helpful changes. To test the code, you can bind a key to createbullet ingame and that will fire a bullet from your view with a line drawn along its path.

Body

This code is WIP by ts2do

game_shared

bullet_manager.h

#include "ammodef.h"
#define BULLET_SPEED 240//inches per hundredths of a second
#define BUTTER_MODE -1
#define ONE_HIT_MODE -2

#ifdef CLIENT_DLL
class C_BulletManager;
extern C_BulletManager *g_pBulletManager;
#define CBulletManager C_BulletManager


#else //!CLIENT_DLL
class CBulletManager;
extern CBulletManager *g_pBulletManager;
#endif //CLIENT_DLL

inline CBulletManager *BulletManager()
{
	return g_pBulletManager;
}

extern ConVar g_debug_bullets;
class CSimulatedBullet
{
public:
	CSimulatedBullet()
	{
		m_vecOrigin.Init();
		m_vecDirShooting.Init();
		m_flInitialBulletSpeed = m_flBulletSpeed = BULLET_SPEED;
		m_flEntryDensity = m_flLagCompensation = 0.0f;
		m_nFlags = (FireBulletsFlags_t)0;
		m_iDamage = m_iAmmoType = m_nDamageType = 0;
	}
	CSimulatedBullet( CBaseEntity *pCaller, CBaseEntity *pAttacker, CBaseEntity *pAdditionalIgnoreEnt,
						int ammoType, int damageType, int nFlags, Vector &vecDirShooting,
						Vector &vecOrigin, int iDamage, float flLagCompensation )
	{
		m_nFlags = (FireBulletsFlags_t)nFlags;
		m_iAmmoType = ammoType;
		m_nDamageType = damageType;
		m_vecOrigin = vecOrigin;
		m_vecDirShooting = vecDirShooting;
		m_flInitialBulletSpeed = m_flBulletSpeed = GetAmmoDef()->GetAmmoOfIndex(ammoType)->flFeetPerSecond * 0.12;
		//m_flInitialBulletSpeed = m_flBulletSpeed = BULLET_SPEED;
		m_flEntryDensity = 0.0f;
		m_flLagCompensation = 100*flLagCompensation;
		m_iDamage = iDamage;
		m_hCaller = pCaller;
#ifndef CLIENT_DLL
		m_pIgnoreList = new CTraceFilterSimpleList(COLLISION_GROUP_NONE);
		m_pIgnoreList->AddEntityToIgnore(pAttacker);
		if(pAdditionalIgnoreEnt!=NULL)
			m_pIgnoreList->AddEntityToIgnore(pAdditionalIgnoreEnt);
#endif
		m_pTwoEnts = new CTraceFilterSkipTwoEntities(pAttacker,pAdditionalIgnoreEnt,COLLISION_GROUP_NONE);
	}
	~CSimulatedBullet()
	{
#ifndef CLIENT_DLL
		//leave the compensation considerations because they're entities
		delete m_pIgnoreList;
#endif
		delete m_pTwoEnts;
	}
	inline float BulletSpeedRatio(void)
	{
		return m_flBulletSpeed/m_flInitialBulletSpeed;
	}
#ifdef GAME_DLL
	void EntityImpact(CBaseEntity *pHit);
#endif
	inline bool IsInWorld(void)
	{
		if (m_vecOrigin.x >= MAX_COORD_INTEGER) return false;
		if (m_vecOrigin.y >= MAX_COORD_INTEGER) return false;
		if (m_vecOrigin.z >= MAX_COORD_INTEGER) return false;
		if (m_vecOrigin.x <= MIN_COORD_INTEGER) return false;
		if (m_vecOrigin.y <= MIN_COORD_INTEGER) return false;
		if (m_vecOrigin.z <= MIN_COORD_INTEGER) return false;
		return true;
	}
	void SimulateBullet(int index,float flTime=1.0f);
	inline float LagCompensation(void)
	{
		return m_flLagCompensation;
	}
	inline int AmmoIndex(void)
	{
		return m_iAmmoType;
	}
private:
	bool m_bWasInWater;

	CTraceFilterSkipTwoEntities *m_pTwoEnts;
#ifndef CLIENT_DLL
	CTraceFilterSimpleList *m_pIgnoreList;//already hit
	CUtlVector<CBaseEntity *> m_pCompensationConsiderations;//Couldn't resist
#endif

	EHANDLE m_hCaller;

	FireBulletsFlags_t m_nFlags;

	float m_flBulletSpeed;
	float m_flEntryDensity;
	float m_flInitialBulletSpeed;
	float m_flLagCompensation;

	int m_iAmmoType;
	int m_iDamage;
	int m_nDamageType;

	Vector m_vecDirShooting;
	Vector m_vecOrigin;
};
class CBulletManager : public CBaseEntity
{
	DECLARE_CLASS( CBulletManager, CBaseEntity );
public:
	CUtlVector<CSimulatedBullet*> m_pBullets;

	CBulletManager();
#ifdef CLIENT_DLL
	void ClientThink(void);
#else
	void Spawn(void);
	void Think(void);
#endif
	void AddBullet(CSimulatedBullet *pBullet);
	void RemoveBullet(int index);
};

bullet_manager.cpp

#include "cbase.h"
#include "util_shared.h"
#include "bullet_manager.h"
#include "shot_manipulator.h"
#pragma warning(disable:4800)
#ifdef CLIENT_DLL
ConVar g_cl_debug_bullets( "g_cl_debug_bullets", "0", FCVAR_CHEAT );
C_BulletManager *g_pBulletManager = new C_BulletManager();
#else
ConVar g_debug_bullets( "g_debug_bullets", "0", FCVAR_CHEAT );
CBulletManager *g_pBulletManager;
#endif

LINK_ENTITY_TO_CLASS( bullet_manager, CBulletManager );
CBulletManager::CBulletManager()
{
	Q_memset( m_rgBullets, 0, MAX_BULLETS );
	m_iLastBullet = -1;
}
#ifdef CLIENT_DLL
#include "engine/ivdebugoverlay.h"
CON_COMMAND_F(createbullet,NULL,FCVAR_CHEAT)
{
	Assert(ClientBulletManager());
	if(!ClientBulletManager())
		return;
	Vector dir;
	g_pLocalPlayer->EyeVectors(&dir);
	FireBulletsInfo_t info(1,g_pLocalPlayer->EyePosition(),dir,vec3_origin,0,0);
	info.m_pAttacker = g_pLocalPlayer;
	engine->ServerCmd(VarArgs("createbullet_s %f\n",gpGlobals->curtime));
	ClientBulletManager()->AddBullet(info,0.0f);
}
#else
CON_COMMAND_F(createbullet_s,NULL,FCVAR_CHEAT)
{
	Assert(BulletManager());
	if(!BulletManager())
		return;
	CBasePlayer *pPlayer = UTIL_GetCommandClient();
	if(!pPlayer)
		return;
	Vector dir;
	pPlayer->EyeVectors(&dir);
	FireBulletsInfo_t info(1,pPlayer->EyePosition(),dir,vec3_origin,0,0);
	info.m_pAttacker = pPlayer;
	float lag = gpGlobals->curtime - atof(engine->Cmd_Argv(1));
	if(lag<0.0f||lag==gpGlobals->curtime)
		lag=0.0f;
	BulletManager()->AddBullet(info,lag);
}
#endif
void CBulletManager::Spawn(void)
{
	g_pBulletManager = this;
#ifdef CLIENT_DLL
	ClientThink();
#else
	Think();
#endif
}
void CBulletManager::SimulateBullet(int index, float time/*=1.0f 100ths of sec*/)
{
#define CUR m_rgBullets[index]
	trace_t trace, trace_back;
	Vector m_vOldOrigin(CUR.m_vOrigin);
	Vector m_vTraceStart(CUR.m_vOrigin);
	DevMsg("BulletSpeed %f\n",CUR.m_flBulletSpeed);
	Vector vecNewRay = CUR.m_Bullet.m_vecDirShooting * CUR.m_flBulletSpeed * time;
	CUR.m_vOrigin += vecNewRay;//in/100th of a sec * 100th of a sec
	bool bInWater = UTIL_PointContents(CUR.m_vOrigin)&MASK_SPLITAREAPORTAL;
	if(CUR.m_bWasInWater!=bInWater)
	{
#ifdef CLIENT_DLL
		//TODO: water impact effect
		//CBaseEntity::HandleShotImpactingWater
#endif //CLIENT_DLL
	}
	if(bInWater)
	{
#ifdef CLIENT_DLL
		//TODO: 1 bubble clientside
#endif //CLIENT_DLL
	}
	CUR.m_bWasInWater = bInWater;
	Vector vecEntryPosition;
	Vector vecExitPosition;
	float flPenetrationDistance = 0.0f;
	do
	{
		UTIL_TraceLine( m_vTraceStart, CUR.m_vOrigin, MASK_SHOT, CUR.m_pTwoEnts, &trace );
		if(!(trace.surface.flags&SURF_SKY))
		{
			if(trace.allsolid)//in solid
			{
				trace.endpos = CUR.m_vOrigin;
				trace.fraction = 1.0f;
				CUR.m_flBulletSpeed -= CUR.m_flBulletSpeed * CUR.m_flEntryDensity / 1000.0f;
				break;
			}
			else if(trace.startsolid)//exit solid
			{
#ifdef CLIENT_DLL
				//TODO: penetration surface impact stuff
#endif //CLIENT_DLL
				vecExitPosition = trace.fractionleftsolid * vecNewRay + m_vTraceStart;
				flPenetrationDistance = vecEntryPosition.DistTo(vecExitPosition);
				CUR.m_flBulletSpeed -= flPenetrationDistance * CUR.m_flEntryDensity / 1000.0f;
			}
			else if(trace.fraction!=1.0f)//hit solid
			{
				if(FStrEq(trace.surface.name,"tools/toolsblockbullets"))
				{
					RemoveBullet(index);
					return;
				}
#ifdef CLIENT_DLL
				//TODO: surface impact stuff
#endif //CLIENT_DLL
				CUR.m_flEntryDensity = physprops->GetSurfaceData(trace.surface.surfaceProps)->physics.density;
				vecEntryPosition = trace.endpos;
#ifdef GAME_DLL
				if(trace.DidHitNonWorldEntity())
				{
					if(CUR.m_pIgnoreList->ShouldHitEntity(trace.m_pEnt,MASK_SHOT))
					{
						CUR.m_pIgnoreList->AddEntityToIgnore(trace.m_pEnt);
						//TODO: entity impact stuff
					}
				}
#endif //GAME_DLL
			}
		}
		m_vTraceStart = trace.endpos + CUR.m_Bullet.m_vecDirShooting;
	}while(trace.endpos!=CUR.m_vOrigin&&CUR.m_flBulletSpeed>0.0f);

#ifdef GAME_DLL
	if(g_debug_bullets.GetBool())
	{
		NDebugOverlay::Line(m_vOldOrigin,CUR.m_vOrigin, 255, 255, 255, true, 10.0f );
	}
#else //!GAME_DLL
	if(g_cl_debug_bullets.GetBool())
	{
		debugoverlay->AddLineOverlay(m_vTraceStart, CUR.m_vOrigin, 255, 0, 0, true, 10.0f);
	}
#endif

	if(CUR.m_flBulletSpeed<=0.0f||!IsInWorld(index))
		RemoveBullet(index);
#undef CUR
}
#ifdef CLIENT_DLL
void CBulletManager::ClientThink(void)
#else
void CBulletManager::Think(void)
#endif
{
	for(int x=0;x<=m_iLastBullet;x++)
	{
		SimulateBullet(x);
	}
#ifdef CLIENT_DLL
	SetNextClientThink
#else
	SetNextThink
#endif
		( gpGlobals->curtime + 0.01f );
}
void CBulletManager::AddBullet(FireBulletsInfo_t &bullet,float lagCompensation)
{
	if (bullet.m_iAmmoType == -1)
	{
		DevMsg("ERROR: Undefined ammo type!\n");
		return;
	}
	if(m_iLastBullet==MAX_BULLETS-1)//256 simultaneous bullets in the air is mayhem
	{//let's do something reckless on bullet mayhem
		Assert(m_iLastBullet!=MAX_BULLETS-1);
		Warning("Bullet queue filled (Removing bullet #0)\n");
		RemoveBullet(0);
	}
	else
		m_iLastBullet++;
	DevMsg("Bullet Created (%i) LagCompensation %f\n",m_iLastBullet,lagCompensation);
	CShotManipulator Manipulator( bullet.m_vecDirShooting );
	bullet.m_vecDirShooting = Manipulator.ApplySpread(bullet.m_vecSpread);
	m_rgBullets[m_iLastBullet] = SimulatedBullet_t(bullet,lagCompensation);
	if(lagCompensation!=0.0f)
		SimulateBullet(m_iLastBullet, lagCompensation*100);
}
void CBulletManager::RemoveBullet(int index)
{
	if(m_iLastBullet!=index)
	{
		m_rgBullets[index].DeletePointers();
		m_rgBullets[index] = m_rgBullets[m_iLastBullet];
		DevMsg("Bullet #%i Destroyed; Replacing with #%i\n",index, m_iLastBullet);
	}
	else
	{
		m_rgBullets[index].DeletePointers();
		DevMsg("Bullet #%i Destroyed\n",index);
	}
	m_rgBullets[m_iLastBullet] = SimulatedBullet_t();
	m_iLastBullet--;
}
inline bool CBulletManager::IsInWorld(int index)
{
	if (m_rgBullets[index].m_vOrigin.x >= MAX_COORD_INTEGER) return false;
	if (m_rgBullets[index].m_vOrigin.y >= MAX_COORD_INTEGER) return false;
	if (m_rgBullets[index].m_vOrigin.z >= MAX_COORD_INTEGER) return false;
	if (m_rgBullets[index].m_vOrigin.x <= MIN_COORD_INTEGER) return false;
	if (m_rgBullets[index].m_vOrigin.y <= MIN_COORD_INTEGER) return false;
	if (m_rgBullets[index].m_vOrigin.z <= MIN_COORD_INTEGER) return false;
	return true;
}

hl2mp_gamerules.cpp

Change GetAmmoDef to the following:

CAmmoDef *GetAmmoDef()
{
	static CAmmoDef def;
	static bool bInitted = false;
	
	if ( !bInitted )
	{
		bInitted = true;
		//		Name		Damage				Tracer			PlrDmg	NPCDmg	MaxCarry	ft/sec	Physics Force Impulse		Flags
		def.AddAmmoType("AR2",		DMG_BULLET,			TRACER_LINE_AND_WHIZ,	0,	0,	60,		1225,	BULLET_IMPULSE(200, 1225),	0 );
		def.AddAmmoType("AR2AltFire",	DMG_DISSOLVE,			TRACER_NONE,		0,	0,	3,		0,	0,				0 );
		def.AddAmmoType("Pistol",	DMG_BULLET,			TRACER_LINE_AND_WHIZ,	0,	0,	150,		1225,	BULLET_IMPULSE(200, 1225),	0 );
		def.AddAmmoType("SMG1",		DMG_BULLET,			TRACER_LINE_AND_WHIZ,	0,	0,	225,		1225,	BULLET_IMPULSE(200, 1225),	0 );
		def.AddAmmoType("357",		DMG_BULLET,			TRACER_LINE_AND_WHIZ,	0,	0,	12,		5000,	BULLET_IMPULSE(800, 5000),	0 );
		def.AddAmmoType("XBowBolt",	DMG_BULLET,			TRACER_LINE,		0,	0,	10,		8000,	BULLET_IMPULSE(800, 8000),	0 );
		def.AddAmmoType("Buckshot",	DMG_BULLET | DMG_BUCKSHOT,	TRACER_LINE,		0,	0,	30,		1200,	BULLET_IMPULSE(400, 1200),	0 );
		def.AddAmmoType("RPG_Round",	DMG_BURN,			TRACER_NONE,		0,	0,	3,		0,	0,				0 );
		def.AddAmmoType("SMG1_Grenade",	DMG_BURN,			TRACER_NONE,		0,	0,	3,		0,	0,				0 );
		def.AddAmmoType("Grenade",	DMG_BURN,			TRACER_NONE,		0,	0,	5,		0,	0,				0 );
		def.AddAmmoType("slam",		DMG_BURN,			TRACER_NONE,		0,	0,	5,		0,	0,				0 );
	}

	return &def;
}

As you can see, the bullet speed is derived from the second argument of the bullet impulses.

ammodef.h

Change the Ammo_t structure to the following:

struct Ammo_t 
{
	char 					*pName;
	int					nDamageType;
	int					eTracerType;
	float					physicsForceImpulse;
	float					flFeetPerSecond;
	int					nMinSplashSize;
	int					nMaxSplashSize;

	int					nFlags;

	// Values for player/NPC damage and carrying capability
	// If the integers are set, they override the CVars
	int					pPlrDmg;		// CVar for player damage amount
	int					pNPCDmg;		// CVar for NPC damage amount
	int					pMaxCarry;		// CVar for maximum number can carry
	const ConVar*				pPlrDmgCVar;		// CVar for player damage amount
	const ConVar*				pNPCDmgCVar;		// CVar for NPC damage amount
	const ConVar*				pMaxCarryCVar;		// CVar for maximum number can carry
};

---

Change the first two AddAmmoType function prototypes to the following:

	void				AddAmmoType(char const* name, int damageType, int tracerType,
							int plr_dmg, int npc_dmg, int carry,
							float ftpersec, float physicsForceImpulse,
							int nFlags, int minSplashSize = 4,
							int maxSplashSize = 8 );

	void				AddAmmoType(char const* name, int damageType, int tracerType,
							char const* plr_cvar, char const* npc_var,
							char const* carry_cvar, float ftpersec,
							float physicsForceImpulse, int nFlags,
							int minSplashSize = 4, int maxSplashSize = 8 );

ammodef.cpp

Add	float ftpersec,
Before both	float physicsForceImpulse,

---

Add	m_AmmoType[m_nAmmoIndex].flFeetPerSecond = ftpersec;
After both	m_AmmoType[m_nAmmoIndex].physicsForceImpulse = physicsForceImpulse;

Implementation

bullet_manager entity

gamerules.cpp

Add	#include "bullet_manager.h"
After	#include "filesystem.h"

---

Add	g_pBulletManager = (CBulletManager*)CBaseEntity::Create( "bullet_manager", vec3_origin, vec3_angle );
After	g_pPlayerResource = (CPlayerResource*)CBaseEntity::Create( "player_manager", vec3_origin, vec3_angle );