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 parabola drawn along its path.

Body

This code is WIP by ts2do

bullet_manager.h

#define MAX_BULLETS 256
#define BULLET_SPEED 240//inches per hundredths of a second
class CBulletManager;
extern CBulletManager *g_pBulletManager;
inline CBulletManager *BulletManager()
{
	return g_pBulletManager;
}
extern ConVar g_debug_bullets;
struct SimulatedBullet_t
{
	SimulatedBullet_t()
	{
		m_Bullet = FireBulletsInfo_t();
		m_vOrigin = vec3_origin;
		m_flInitialBulletSpeed = m_flBulletSpeed = BULLET_SPEED;
		m_flBulletTime = 0;
		m_flLagCompensation = 0.0f;
	}

	SimulatedBullet_t( FireBulletsInfo_t &bullet, float lagCompensation )
	{
		m_Bullet = bullet;
		m_vOrigin = bullet.m_vecSrc;
		m_flInitialBulletSpeed = m_flBulletSpeed = BULLET_SPEED;
		m_flBulletTime = 0;
		m_flLagCompensation = lagCompensation; 
	}

	FireBulletsInfo_t m_Bullet;
	Vector m_vOrigin;
	float m_flBulletSpeed;
	float m_flInitialBulletSpeed;
	float m_flBulletTime;
	float m_flLagCompensation;
	CUtlVector<CBaseEntity *> m_pCompensationConsiderations;//Couldn't resist
	CUtlVector<CBaseEntity *> m_pHit;
	float m_flLastDensity;
};
class CBulletManager : public CBaseEntity
{
	DECLARE_CLASS( CBulletManager, CBaseEntity );
public:
	SimulatedBullet_t m_rgBullets[MAX_BULLETS];
	int m_iLastBullet;

	CBulletManager();
	void Spawn(void);
	void Think(void);
	void SimulateBullet(int index, float time=1.0f);
	void AddBullet(FireBulletsInfo_t &bullet, float lagCompensation);
	void RemoveBullet(int index);
	inline bool IsInWorld(int index);
	inline float GetSpeedMod(int index);
};

bullet_manager.cpp

#include "cbase.h"
#include "movevars_shared.h"
#include "util_shared.h"
#include "bullet_manager.h"
ConVar g_debug_bullets( "g_debug_bullets", "0", FCVAR_CHEAT );
CBulletManager *g_pBulletManager;
LINK_ENTITY_TO_CLASS( bullet_manager, CBulletManager );
CBulletManager::CBulletManager()
{
	Q_memset( m_rgBullets, 0, MAX_BULLETS );
	m_iLastBullet = -1;
}
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=0.0f;
	BulletManager()->AddBullet(info,lag);
}
void CBulletManager::Spawn(void)
{
	Think();
}
void CBulletManager::SimulateBullet(int index, float time/*=1.0f 100ths of sec*/)
{
#define CUR m_rgBullets[index]
	CUR.m_flBulletTime += time;
	Vector m_vOldOrigin = CUR.m_vOrigin;
	DevMsg("BulletSpeed %f LastDensity %f\n",CUR.m_flBulletSpeed, CUR.m_flLastDensity);
	CUR.m_vOrigin += CUR.m_Bullet.m_vecDirShooting * CUR.m_flBulletSpeed * time;//in/100th of a sec * 100th of a sec

	CTraceFilterSkipTwoEntities traceFilter( CUR.m_Bullet.m_pAttacker, CUR.m_Bullet.m_pAdditionalIgnoreEnt, COLLISION_GROUP_NONE );
	trace_t trace;
	UTIL_TraceLine( m_vOldOrigin, CUR.m_vOrigin, MASK_SHOT, &traceFilter, &trace );

	if(trace.m_pEnt)
	{
		if(!(CUR.m_pHit).Find(trace.m_pEnt))
		{
		}
	}
	if(CUR.m_flLastDensity!=0.0f)
	{
		if(trace.allsolid)
		{
			CUR.m_flBulletSpeed -= GetSpeedMod(index);
		}
		else if(trace.surface.name[0]!='*'&&!(trace.surface.flags & SURF_SKY))
		{//make sure we didnt hit an invalid (nodraw) or sky material
			if(trace.startsolid)
			{
				CUR.m_flBulletSpeed -= trace.fractionleftsolid * GetSpeedMod(index);
				CUR.m_flLastDensity = 0.0f;
			}
			if( trace.fraction != 1.0f)
			{
				CUR.m_flLastDensity = physprops->GetSurfaceData(trace.surface.surfaceProps)->physics.density;
			}
		}
	}
#ifndef _DEBUG
	if(g_debug_bullets.GetBool())
#endif
	{
		NDebugOverlay::Line(m_vOldOrigin,CUR.m_vOrigin, 255, 255, 255, true, 0.25f );
	}

	if(CUR.m_flBulletSpeed<=0.0f||!IsInWorld(index))
		RemoveBullet(index);
#undef CUR
}
void CBulletManager::Think(void)
{
	for(int x=0;x<=m_iLastBullet;x++)
	{
		SimulateBullet(x);
	}
	SetNextThink( gpGlobals->curtime + 0.01f );
}
void CBulletManager::AddBullet(FireBulletsInfo_t &bullet,float lagCompensation)
{
	lagCompensation+=0.1f;
	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);
	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] = m_rgBullets[m_iLastBullet];
		DevMsg("Bullet #%i Destroyed; Replacing with #%i\n",index, m_iLastBullet);
	}
	else
		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;
}
inline float CBulletManager::GetSpeedMod(int index)
{
	return fabs(100.0f-m_rgBullets[index].m_flLastDensity) / 100.0f;
}

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 );