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 parabola drawn along its path.

Body

This code is WIP by ts2do

bullet_manager.h

#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,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);
}
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;
	trace_t trace, trace_back;
	Vector m_vOldOrigin, m_vTraceStart;
	m_vOldOrigin = m_vTraceStart = 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

	int sentinal=0;//debugging purposes
	do
	{
		UTIL_TraceLine( m_vTraceStart + CUR.m_Bullet.m_vecDirShooting, CUR.m_vOrigin, MASK_SHOT, CUR.m_pIgnoreList, &trace );
		DevMsg("%f\n",trace.endpos);
		if(trace.DidHitNonWorldEntity())
		{
			CUR.m_pIgnoreList->AddEntityToIgnore(trace.m_pEnt);
			//Do entity impact stuff here
		}
		//Do surface impact stuff here
		UTIL_TraceLine( m_vTraceStart, m_vOldOrigin, MASK_SHOT, CUR.m_pTraceBack, &trace_back );
		//Do penetration surface impact stuff here
		m_vTraceStart = trace.endpos;
		sentinal++;
	}while(trace.endpos!=CUR.m_vOrigin&&sentinal<20);
	if(sentinal==20)
		DevMsg("INFINITE LOOP SPOTTED!\n");

	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, 10.0f );
		NDebugOverlay::Cross3D(CUR.m_vOrigin, 16, 255, 0, 0, true, 10.0f);
	}

	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)
{
	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].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;
}
inline float CBulletManager::GetSpeedMod(int index)
{
	return fabs(100.0f-m_rgBullets[index].m_flLastDensity) / 100.0f;
}

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 );

Making weapons shoot them

Retrieved from "https://developer.valvesoftware.com/w/index.php?title=Simulated_Bullets&oldid=17103"