Simulated Bullets

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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.pngNote: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 );

Making weapons shoot them

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