src/audio/AudioLogic.cpp

@@ -2347,12 +2347,18 @@ PlayCruising:
 			SampleManager.StopChannel(CHANNEL_PLAYER_VEHICLE_ENGINE);
 			if (isMoped || accelerateState >= 150 && wheelsOnGround && brakeState <= 0 && !params.m_pVehicle->bIsHandbrakeOn
 				&& !lostTraction && currentGear >= params.m_pTransmission->nNumberOfGears - 1) {
+#ifdef FIX_BUGS
+				// Prevent the fake top gear ("cruise gear") rising in pitch too quickly at high FPS.
+				if (CTimer::GetLogicalFramesPassed())
+#endif
+				{
 					if (accelerateState >= 220 && params.m_fVelocityChange + 0.001f >= velocityChangeForAudio) {
 						if (nCruising < 800)
 							++nCruising;
 					} else if (nCruising > 3) {
 						--nCruising;
 					}
+				}
 				freq = 27 * nCruising + freqModifier + 22050;
 				if (engineSoundType == SFX_BANK_TRUCK)
 					freq /= 2;

src/core/Cam.cpp

@@ -3895,10 +3895,12 @@ CCam::Process_Debug(const CVector&, float, float, float)
 	if(Alpha > DEGTORAD(89.5f)) Alpha = DEGTORAD(89.5f);
 	else if(Alpha < DEGTORAD(-89.5f)) Alpha = DEGTORAD(-89.5f);
 
+	const float TimeStep = CTimer::GetTimeStepNonClipped();
+
 	if(CPad::GetPad(1)->GetSquare() || KEYDOWN('W'))
-		Speed += 0.1f;
+		Speed += 0.1f * TimeStep;
 	else if(CPad::GetPad(1)->GetCross() || KEYDOWN('S'))
-		Speed -= 0.1f;
+		Speed -= 0.1f * TimeStep;
 	else
 		Speed = 0.0f;
 	if(Speed > 70.0f) Speed = 70.0f;
@@ -3906,9 +3908,9 @@ CCam::Process_Debug(const CVector&, float, float, float)
 
 
 	if(KEYDOWN(rsRIGHT) || KEYDOWN('D'))
-		PanSpeedX += 0.1f;
+		PanSpeedX += 0.1f * TimeStep;
 	else if(KEYDOWN(rsLEFT) || KEYDOWN('A'))
-		PanSpeedX -= 0.1f;
+		PanSpeedX -= 0.1f * TimeStep;
 	else
 		PanSpeedX = 0.0f;
 	if(PanSpeedX > 70.0f) PanSpeedX = 70.0f;
@@ -3916,23 +3918,22 @@ CCam::Process_Debug(const CVector&, float, float, float)
 
 
 	if(KEYDOWN(rsUP))
-		PanSpeedY += 0.1f;
+		PanSpeedY += 0.1f * TimeStep;
 	else if(KEYDOWN(rsDOWN))
-		PanSpeedY -= 0.1f;
+		PanSpeedY -= 0.1f * TimeStep;
 	else
 		PanSpeedY = 0.0f;
 	if(PanSpeedY > 70.0f) PanSpeedY = 70.0f;
 	if(PanSpeedY < -70.0f) PanSpeedY = -70.0f;
 
-
 	Front = TargetCoors - Source;
 	Front.Normalise();
-	Source = Source + Front*Speed;
+	Source = Source + Front * Speed * TimeStep;
 
 	Up = CVector{ 0.0f, 0.0f, 1.0f };
 	CVector Right = CrossProduct(Front, Up);
 	Up = CrossProduct(Right, Front);
-	Source = Source + Up*PanSpeedY + Right*PanSpeedX;
+	Source = Source + Up * PanSpeedY * TimeStep + Right * PanSpeedX * TimeStep;
 
 	if(Source.z < -450.0f)
 		Source.z = -450.0f;
@@ -3955,11 +3956,7 @@ CCam::Process_Debug(const CVector&, float, float, float)
 		Source.y += 1.0f;
 	GetVectorsReadyForRW();
 
-#ifdef FIX_BUGS
 	CPad::GetPad(0)->SetDisablePlayerControls(PLAYERCONTROL_CAMERA);
-#else
-	CPad::GetPad(0)->DisablePlayerControls = PLAYERCONTROL_CAMERA;
-#endif
 
 	if(CPad::GetPad(1)->GetLeftShockJustDown() && gbBigWhiteDebugLightSwitchedOn)
 		CShadows::StoreShadowToBeRendered(SHADOWTYPE_ADDITIVE, gpShadowExplosionTex, &Source,

src/entities/Physical.cpp

@@ -590,7 +590,12 @@ CPhysical::ApplyAirResistance(void)
 	}else if(GetStatus() != STATUS_GHOST){ 
 		float f = Pow(1.0f/Abs(1.0f + m_fAirResistance*0.5f*m_vecMoveSpeed.MagnitudeSqr()), CTimer::GetTimeStep());
 		m_vecMoveSpeed *= f;
+#ifdef FIX_BUGS
+		// Fix too much friction at high FPS (evil cause of bad vehicle handling, rear tires unable to lose traction, etc!)
+		m_vecTurnSpeed *= Pow(0.99f, CTimer::GetTimeStepFix());
+#else
 		m_vecTurnSpeed *= 0.99f;
+#endif
 	}
 }
 
@@ -1071,6 +1076,10 @@ CPhysical::ApplyFriction(CPhysical *B, float adhesiveLimit, CColPoint &colpoint)
 		if(fOtherSpeedA > speedSum){
 			impulseA = (speedSum - fOtherSpeedA) * A->m_fMass;
 			impulseB = (speedSum - fOtherSpeedB) * B->m_fMass;
+#ifdef FIX_BUGS
+			impulseA *= CTimer::GetTimeStepFix();
+			impulseB *= CTimer::GetTimeStepFix();
+#endif
 			impulseLimit = adhesiveLimit*CTimer::GetTimeStep();
 			if(impulseA < -impulseLimit) impulseA = -impulseLimit;
 #ifdef FIX_BUGS
@@ -1107,6 +1116,10 @@ CPhysical::ApplyFriction(CPhysical *B, float adhesiveLimit, CColPoint &colpoint)
 		if(fOtherSpeedA > speedSum){
 			impulseA = (speedSum - fOtherSpeedA) * A->m_fMass;
 			impulseB = (speedSum - fOtherSpeedB) * massB;
+#ifdef FIX_BUGS
+			impulseA *= CTimer::GetTimeStepFix();
+			impulseB *= CTimer::GetTimeStepFix();
+#endif
 			impulseLimit = adhesiveLimit*CTimer::GetTimeStep();
 			if(impulseA < -impulseLimit) impulseA = -impulseLimit;
 			if(impulseB > impulseLimit) impulseB = impulseLimit;
@@ -1140,6 +1153,10 @@ CPhysical::ApplyFriction(CPhysical *B, float adhesiveLimit, CColPoint &colpoint)
 		if(fOtherSpeedA > speedSum){
 			impulseA = (speedSum - fOtherSpeedA) * massA;
 			impulseB = (speedSum - fOtherSpeedB) * B->m_fMass;
+#ifdef FIX_BUGS
+			impulseA *= CTimer::GetTimeStepFix();
+			impulseB *= CTimer::GetTimeStepFix();
+#endif
 			impulseLimit = adhesiveLimit*CTimer::GetTimeStep();
 			if(impulseA < -impulseLimit) impulseA = -impulseLimit;
 			if(impulseB > impulseLimit) impulseB = impulseLimit;
@@ -1174,6 +1191,10 @@ CPhysical::ApplyFriction(CPhysical *B, float adhesiveLimit, CColPoint &colpoint)
 		if(fOtherSpeedA > speedSum){
 			impulseA = (speedSum - fOtherSpeedA) * massA;
 			impulseB = (speedSum - fOtherSpeedB) * massB;
+#ifdef FIX_BUGS
+			impulseA *= CTimer::GetTimeStepFix();
+			impulseB *= CTimer::GetTimeStepFix();
+#endif
 			impulseLimit = adhesiveLimit*CTimer::GetTimeStep();
 			if(impulseA < -impulseLimit) impulseA = -impulseLimit;
 			if(impulseB > impulseLimit) impulseB = impulseLimit;
@@ -1214,6 +1235,9 @@ CPhysical::ApplyFriction(float adhesiveLimit, CColPoint &colpoint)
 			// not really impulse but speed
 			// maybe use ApplyFrictionMoveForce instead?
 			fImpulse = -fOtherSpeed;
+#ifdef FIX_BUGS
+			fImpulse *= CTimer::GetTimeStepFix();
+#endif
 			impulseLimit = adhesiveLimit*CTimer::GetTimeStep() / m_fMass;
 			if(fImpulse < -impulseLimit) fImpulse = -impulseLimit;
 			CVector vImpulse = frictionDir*fImpulse;
@@ -1235,6 +1259,9 @@ CPhysical::ApplyFriction(float adhesiveLimit, CColPoint &colpoint)
 			frictionDir = vOtherSpeed * (1.0f/fOtherSpeed);
 #endif
 			fImpulse = -fOtherSpeed * m_fMass;
+#ifdef FIX_BUGS
+			fImpulse *= CTimer::GetTimeStepFix();
+#endif
 			impulseLimit = adhesiveLimit*CTimer::GetTimeStep() * 1.5;
 			if(fImpulse < -impulseLimit) fImpulse = -impulseLimit;
 			ApplyFrictionMoveForce(frictionDir*fImpulse);
@@ -1834,9 +1861,16 @@ CPhysical::ProcessCollisionSectorList(CPtrList *lists)
 					   A->GetStatus() == STATUS_PLAYER && A->IsVehicle() &&
 					   Abs(A->m_vecMoveSpeed.x) > 0.2f &&
 					   Abs(A->m_vecMoveSpeed.y) > 0.2f){
+#ifdef FIX_BUGS
+						// Fix vehicles having lower turning circles at high FPS
+						A->m_vecMoveFriction.x += CTimer::GetTimeStepFix() * moveSpeed.x * -0.3f / numCollisions;
+						A->m_vecMoveFriction.y += CTimer::GetTimeStepFix() * moveSpeed.y * -0.3f / numCollisions;
+						A->m_vecTurnFriction += CTimer::GetTimeStepFix() * turnSpeed * -0.3f / numCollisions;
+#else
 						A->m_vecMoveFriction.x += moveSpeed.x * -0.3f / numCollisions;
 						A->m_vecMoveFriction.y += moveSpeed.y * -0.3f / numCollisions;
 						A->m_vecTurnFriction += turnSpeed * -0.3f / numCollisions;
+#endif
 					}
 
 					if(B->IsObject() && Bobj->m_nCollisionDamageEffect && maxImpulseA > 20.0f)

src/extras/debugmenu.cpp

@@ -6,6 +6,7 @@
 #include "Timer.h"
 #include "rtcharse.h"
 #include "re3_inttypes.h"
+#include "Frontend.h"
 #include "debugmenu.h"
 #include <new>
 
@@ -1017,6 +1018,10 @@ DebugMenuProcess(void)
 	CPad *pad = CPad::GetPad(0);
 	if(CTRLJUSTDOWN('M'))
 		menuOn = !menuOn;
+	if (KEYJUSTDOWN(rsF4))
+		FrontEndMenuManager.m_PrefsFrameLimiter = !FrontEndMenuManager.m_PrefsFrameLimiter;
+	if(KEYJUSTDOWN(rsESC)) 
+		menuOn = false;
 	if(!menuOn)
 		return;
 

src/objects/ParticleObject.cpp

@@ -429,6 +429,12 @@ CParticleObject::RemoveObject(void)
 void
 CParticleObject::UpdateAll(void)
 {
+#ifdef FIX_BUGS
+	// Fix particle generation spam at high FPS
+	if (CTimer::GetLogicalFramesPassed() == 0)
+		return;
+#endif
+
 	{
 		CParticleObject *pobj = pCloseListHead;
 		CParticleObject *nextpobj;

src/renderer/Particle.cpp

@@ -1259,8 +1259,11 @@ void CParticle::Update()
 			}
 			
 			vecPos += vecMoveStep;
-			
+#ifdef FIX_BUGS
+			if ( psystem->m_Type == PARTICLE_FIREBALL && CTimer::GetLogicalFramesPassed()) // Fix particle spam at high FPS
+#else
 			if ( psystem->m_Type == PARTICLE_FIREBALL )
+#endif
 			{
 				  AddParticle(PARTICLE_HEATHAZE, particle->m_vecPosition, CVector(0.0f, 0.0f, 0.0f),
 					nil, particle->m_fSize * 5.0f);
@@ -1326,11 +1329,18 @@ void CParticle::Update()
 					
 					fDistToCam = (TheCamera.GetPosition() - vecPos).Magnitude();
 				}
-
+#ifdef FIX_BUGS
+				if ( numWaterDropOnScreen < nMaxDrops && numWaterDropOnScreen < 63
+					&& fDistToCam < 10.0f
+					&& clearWaterDrop == false
+					&& !CGame::IsInInterior() 
+					&& CTimer::GetLogicalFramesPassed()) // Fix waterdrop spam at high FPS
+#else
 				if ( numWaterDropOnScreen < nMaxDrops && numWaterDropOnScreen < 63
 					&& fDistToCam < 10.0f
 					&& clearWaterDrop == false
 					&& !CGame::IsInInterior() )
+#endif
 				{
 					CVector vecWaterdropTarget
 					(
@@ -1411,7 +1421,11 @@ void CParticle::Update()
 				}
 			}
 			
+#ifdef FIX_BUGS
+			if ( !(psystem->Flags & SCREEN_TRAIL) && CTimer::GetLogicalFramesPassed()) // Fix particle over-expansion at high FPS
+#else
 			if ( !(psystem->Flags & SCREEN_TRAIL) )
+#endif
 			{
 				float size;
 
@@ -1701,6 +1715,12 @@ void CParticle::Update()
 				}
 			}
 
+#ifdef FIX_BUGS
+			// Keep particles animating, rotating, fading etc at the right speed
+			// at high or low FPS.
+			for (uint32 i=0; i<CTimer::GetLogicalFramesPassed(); i++)
+#endif
+			{ // -- start FPS fix ---
 			if ( particle->m_nFadeToBlackTimer != 0 )
 			{
 				particle->m_nColorIntensity = Clamp(particle->m_nColorIntensity - particle->m_nFadeToBlackTimer,
@@ -1764,6 +1784,7 @@ void CParticle::Update()
 #else
 				particle->m_nRotation += particle->m_nRotationStep;
 #endif
+			} // -- end FPS fix --
 			
 			if ( particle->m_fCurrentZRadius != 0.0f )
 			{
@@ -1773,6 +1794,16 @@ void CParticle::Update()
 				
 				float fY = (Sin(nSinCosIndex) + Cos(nSinCosIndex)) * particle->m_fCurrentZRadius;
 
+#ifdef FIX_BUGS
+				// Prevent super-fast movement at high FPS
+				// We can use GetTimeSetpFix() here instead of GetLogicalFramesPassed()
+				// so the visual result looks "smooth" on player's screens.  We can't
+				// do this with most of the above Timers because the effects are stored
+				// as uint16's instead of floats, which means tiny changes each frame
+				// are often rounded down to zero change each frame.
+				fX *= CTimer::GetTimeStepFix();
+				fY *= CTimer::GetTimeStepFix();
+#endif
 				vecPos -= particle->m_vecParticleMovementOffset;
 
 				vecPos += CVector(fX, fY, 0.0f);

src/renderer/ParticleType.h

@@ -81,7 +81,7 @@ enum tParticleType
 	PARTICLE_TEST,
 	PARTICLE_BIRD_FRONT,
 	PARTICLE_SHIP_SIDE,
-	PARTICLE_BEASTIE,
+	PARTICLE_BEASTIE,  // "Beasties" look like tree leaves circling up at canopy height, but are also used in other places (eg docks)
 	PARTICLE_RAINDROP_2D,
 	PARTICLE_HEATHAZE,
 	PARTICLE_HEATHAZE_IN_DIST,

src/renderer/WaterLevel.cpp

@@ -921,6 +921,18 @@ CWaterLevel::RenderWater()
 	
 	if ( !CTimer::GetIsPaused() )
 	{
+		#ifdef FIX_BUGS
+			// Stop the  movement of the ocean speeding up at high FPS.
+			// Should be purely aesthetic, affecting only the texture UVs.
+			TEXTURE_ADDU       += windAddUV * CTimer::GetTimeStepFix();
+			TEXTURE_ADDV       += windAddUV * CTimer::GetTimeStepFix();
+
+			_TEXTURE_MASK_ADDU += (Sin(fAngle) 		  * 0.0005f + 1.1f * windAddUV) * CTimer::GetTimeStepFix();
+			_TEXTURE_MASK_ADDV -= (Cos(fAngle * 1.3f) * 0.0005f + 1.2f * windAddUV) * CTimer::GetTimeStepFix();
+
+			_TEXTURE_WAKE_ADDU -= (Sin(fAngle) 		  * 0.0003f + windAddUV) * CTimer::GetTimeStepFix();
+			_TEXTURE_WAKE_ADDV += (Cos(fAngle * 0.7f) * 0.0003f + windAddUV) * CTimer::GetTimeStepFix();
+		#else
 			TEXTURE_ADDU       += windAddUV;
 			TEXTURE_ADDV       += windAddUV;
 
@@ -929,8 +941,10 @@ CWaterLevel::RenderWater()
 
 			_TEXTURE_WAKE_ADDU -= Sin(fAngle) 		 * 0.0003f + windAddUV;
 			_TEXTURE_WAKE_ADDV += Cos(fAngle * 0.7f) * 0.0003f + windAddUV;
+		#endif
 	}
 	
+	// What does this code do?  Are the above equations sometimes unstable and make big numbers?
 	if ( _TEXTURE_MASK_ADDU >= 1.0f )
 		_TEXTURE_MASK_ADDU = 0.0f;
 	if ( _TEXTURE_MASK_ADDV >= 1.0f )
@@ -1954,7 +1968,7 @@ CWaterLevel::RenderWavyMask(float fX, float fY, float fZ,
 #ifndef PC_WATER
 			if (maskMorphVerts[base].z >= fMinSparkZ)
 #else
-			if ( maskMorphVerts[base].z > fMinSparkZ )
+			if (maskMorphVerts[base].z >  fMinSparkZ)
 #endif
 			{
 				switch ( (i + j + randval) & 3 )

src/renderer/Weather.cpp

@@ -169,7 +169,11 @@ void CWeather::Update(void)
 		LightningFlash = false;
 		LightningBurst = false;
 	}
+#ifdef FIX_BUGS
+	else if (CTimer::GetLogicalFramesPassed()) {
+#else
 	else{
+#endif
 		if (LightningBurst) {
 			if ((CGeneral::GetRandomNumber() & 255) >= 32) {
 				// 0.875 probability
@@ -303,7 +307,11 @@ void CWeather::Update(void)
 	TrafficLightBrightness = Max(Foggyness, TrafficLightBrightness);
 	TrafficLightBrightness = Max(Rain, TrafficLightBrightness);
 
+#ifdef FIX_BUGS
+	if (CTimer::GetLogicalFramesPassed()) AddRain();
+#else
 	AddRain();
+#endif
 
 	if ((NewWeatherType == WEATHER_SUNNY || NewWeatherType == WEATHER_EXTRA_SUNNY) &&
 		!CGame::IsInInterior() && !CCutsceneMgr::IsRunning() && (CTimer::GetFrameCounter() & 7) == 0) {
@@ -323,6 +331,11 @@ void CWeather::Update(void)
 
 void CWeather::AddHeatHaze()
 {
+#ifdef FIX_BUGS
+	// Fix particle spam at high FPS
+	if (!CTimer::GetLogicalFramesPassed())
+		return;
+#endif
 	if(TheCamera.Cams[TheCamera.ActiveCam].Mode == CCam::MODE_TOPDOWN ||
 	   TheCamera.Cams[TheCamera.ActiveCam].Mode == CCam::MODE_TOP_DOWN_PED)
 		return;
@@ -338,6 +351,11 @@ void CWeather::AddHeatHaze()
 
 void CWeather::AddBeastie()
 {
+#ifdef FIX_BUGS
+	// Fix particle spam at high FPS.  Beasties look like tree leaves.
+	if (!CTimer::GetLogicalFramesPassed())
+		return;
+#endif
 	if(FindPlayerVehicle() || CTimer::GetFrameCounter()%10 || (CGeneral::GetRandomNumber()&5) == 0)
 		return;
 	CVector pos = TheCamera.GetPosition();

src/vehicles/Automobile.cpp

@@ -235,6 +235,12 @@ CAutomobile::CAutomobile(int32 id, uint8 CreatedBy)
 		bExplosionProof = true;
 		bBulletProof = true;
 	}
+
+#ifdef FIX_BUGS
+	// Probably not neccesary to zero these
+	m_nCarHornTimer = 0;
+	m_fCarHornTimeButtonLastHit = 0.0f;
+#endif
 }
 
 void
@@ -857,8 +863,12 @@ CAutomobile::ProcessControl(void)
 			   (m_aSuspensionSpringRatio[1] < 1.0f || m_aSuspensionSpringRatio[3] < 1.0f))
 				ApplyTurnForce(-GRAVITY*Min(m_fTurnMass, 2500.0f)*GetUp(), -1.0f*GetForward());
 		}
-
+#ifdef FIX_BUGS
+		// Keep brake non-timestepped (so the later ProcessWheel() takes only non-timestepped inputs)
+		brake = m_fBrakePedal * pHandling->fBrakeDeceleration * CTimer::GetDefaultTimeStep();
+#else
 		brake = m_fBrakePedal * pHandling->fBrakeDeceleration * CTimer::GetTimeStep();
+#endif
 		bool neutralHandling = GetStatus() != STATUS_PLAYER && GetStatus() != STATUS_PLAYER_REMOTE && (pHandling->Flags & HANDLING_NEUTRALHANDLING);
 		float brakeBiasFront = neutralHandling ? 1.0f : 2.0f*pHandling->fBrakeBias;
 		float brakeBiasRear  = neutralHandling ? 1.0f : 2.0f-pHandling->fBrakeBias;	// looks like a bug, but it was correct in III...
@@ -1058,12 +1068,7 @@ CAutomobile::ProcessControl(void)
 			float rearBrake = brake;
 			float rearTraction = traction;
 			if(bIsHandbrakeOn){
-#ifdef FIX_BUGS
-				// Not sure if this is needed, but brake usually has timestep as a factor
-				rearBrake = 20000.0f * CTimer::GetTimeStepFix();
-#else
 				rearBrake = 20000.0f;
-#endif
 				if(fwdSpeed > 0.1f && pHandling->Flags & HANDLING_HANDBRAKE_TYRE){
 					m_fTireTemperature += 0.005*CTimer::GetTimeStep();
 					if(m_fTireTemperature > 2.0f)
@@ -1072,8 +1077,11 @@ CAutomobile::ProcessControl(void)
 			}else if(m_doingBurnout && mod_HandlingManager.HasRearWheelDrive(pHandling->nIdentifier)){
 				rearBrake = 0.0f;
 				rearTraction = 0.0f;
-				// BUG: missing timestep
+#ifdef FIX_BUGS
+				ApplyTurnForce(contactPoints[CARWHEEL_REAR_LEFT], -0.001f*m_fTurnMass*m_fSteerAngle*GetRight()*CTimer::GetTimeStepFix());
+#else
 				ApplyTurnForce(contactPoints[CARWHEEL_REAR_LEFT], -0.001f*m_fTurnMass*m_fSteerAngle*GetRight());
+#endif
 			}else if(m_fTireTemperature > 1.0f){
 				rearTraction *= m_fTireTemperature;
 			}
@@ -1364,18 +1372,49 @@ CAutomobile::ProcessControl(void)
 				ReduceHornCounter();
 		}else{
 			if(UsesSiren()){
+#ifdef FIX_BUGS
+				// Allow sirens to be toggled at high FPS
+				const float minPressTime = 100.0f; // milli-seconds
+				bool currentButtonState = Pads[0].bHornHistory[(CPad::HORNHISTORY_SIZE + Pads[0].iCurrHornHistory - 0) % CPad::HORNHISTORY_SIZE]; 
+				bool lastButtonState    = Pads[0].bHornHistory[(CPad::HORNHISTORY_SIZE + Pads[0].iCurrHornHistory - 1) % CPad::HORNHISTORY_SIZE]; // Extra addition of CPad::HORNHISTORY_SIZE avoids modulo of negative numbers
+
+				if (currentButtonState && !lastButtonState)
+				{
+					// Horn button has just been hit
+					m_fCarHornTimeButtonLastHit = CTimer::GetTimeInMilliseconds();
+				}
+				else if (currentButtonState && lastButtonState)
+				{
+					// Horn button is being held down
+					if (CTimer::GetTimeInMilliseconds() - m_fCarHornTimeButtonLastHit >= minPressTime)
+						m_nCarHornTimer = 1; // enable horn
+				}
+				else if (!currentButtonState && lastButtonState)
+				{
+					// Horn button has just been released
+					m_nCarHornTimer = 0;
+					if (CTimer::GetTimeInMilliseconds() - m_fCarHornTimeButtonLastHit < minPressTime) 
+						m_bSirenOrAlarm = !m_bSirenOrAlarm; // Toggle siren-like-feature
+				}
+				else
+				{
+					// Nothing pressed
+					m_nCarHornTimer = 0; // Should not be neccesary, but may as well keep in
+				}
+#else
 				if(Pads[0].bHornHistory[Pads[0].iCurrHornHistory]){
-					if(Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+4) % 5] &&
+					if(Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+4) % CPad::HORNHISTORY_SIZE] &&
-					   Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+3) % 5])
+					   Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+3) % CPad::HORNHISTORY_SIZE])
 						m_nCarHornTimer = 1;
 					else
 						m_nCarHornTimer = 0;
-				}else if(Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+4) % 5] &&
+				}else if(Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+4) % CPad::HORNHISTORY_SIZE] &&
-				         !Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+1) % 5]){
+				         !Pads[0].bHornHistory[(Pads[0].iCurrHornHistory+1) % CPad::HORNHISTORY_SIZE]){
 					m_nCarHornTimer = 0;
 					m_bSirenOrAlarm = !m_bSirenOrAlarm;
 				}else
 					m_nCarHornTimer = 0;
+#endif
 			}else if(GetModelIndex() != MI_VOODOO && !CVehicle::bCheat3 && !carHasNitro){
 				if(!IsAlarmOn()){
 					if(Pads[0].GetHorn())
@@ -5738,8 +5777,14 @@ CAutomobile::ShowAllComps(void)
 void
 CAutomobile::ReduceHornCounter(void)
 {
+#ifdef FIX_BUGS
+	// Make horns last longer (only used by AI drivers?)
+	if(m_nCarHornTimer != 0 && CTimer::GetLogicalFramesPassed())
+		m_nCarHornTimer--;
+#else
 	if(m_nCarHornTimer != 0)
 		m_nCarHornTimer--;
+#endif
 }
 
 void

src/vehicles/Bike.cpp

@@ -722,7 +722,12 @@ CBike::ProcessControl(void)
 		acceleration = pHandling->Transmission.CalculateDriveAcceleration(m_fGasPedal, m_nCurrentGear, m_fChangeGearTime, fwdSpeed, gripCheat);
 		acceleration /= m_fForceMultiplier;
 
+#ifdef FIX_BUGS
+		// Keep timestep out of this, it gets added properly inside ProcessWheel() later.  Fixes weak brakes at high FPS.
+		brake = m_fBrakePedal * pHandling->fBrakeDeceleration * CTimer::GetDefaultTimeStep();
+#else
 		brake = m_fBrakePedal * pHandling->fBrakeDeceleration * CTimer::GetTimeStep();
+#endif
 		bool neutralHandling = GetStatus() != STATUS_PLAYER && GetStatus() != STATUS_PLAYER_REMOTE && (pHandling->Flags & HANDLING_NEUTRALHANDLING);
 		float brakeBiasFront = neutralHandling ? 1.0f : 2.0f*pHandling->fBrakeBias;
 		float brakeBiasRear  = neutralHandling ? 1.0f : 2.0f*(1.0f-pHandling->fBrakeBias);
@@ -882,12 +887,7 @@ CBike::ProcessControl(void)
 			wheelRight.Normalise();
 
 			if(bIsHandbrakeOn){
-#ifdef FIX_BUGS
-				// Not sure if this is needed, but brake usually has timestep as a factor
-				rearBrake = 20000.0f * CTimer::GetTimeStepFix();
-#else
 				rearBrake = 20000.0f;
-#endif
 				m_fTireTemperature = 1.0f;
 			}else if(m_doingBurnout){
 				rearBrake = 0.0f;
@@ -2941,8 +2941,14 @@ CBike::SetupModelNodes(void)
 void
 CBike::ReduceHornCounter(void)
 {
+	#ifdef FIX_BUGS
+	// Make horns last longer (only used by AI drivers?)
+	if(m_nCarHornTimer != 0 && CTimer::GetLogicalFramesPassed())
+		m_nCarHornTimer--;
+	#else
 		if(m_nCarHornTimer != 0)
 			m_nCarHornTimer--;
+	#endif
 }
 
 #ifdef COMPATIBLE_SAVES

src/vehicles/Boat.cpp

@@ -263,9 +263,17 @@ CBoat::ProcessControl(void)
 	}
 
 	// Damage particles
+#ifdef FIX_BUGS
+	if(m_fHealth <= 460.0f && GetStatus() != STATUS_WRECKED &&
+	   Abs(GetPosition().x - TheCamera.GetPosition().x) < 200.0f &&
+	   Abs(GetPosition().y - TheCamera.GetPosition().y) < 200.0f &&
+	   CTimer::GetLogicalFramesPassed() ) // Fix high-FPS particle spam
+	   {
+#else
 	if(m_fHealth <= 460.0f && GetStatus() != STATUS_WRECKED &&
 	   Abs(GetPosition().x - TheCamera.GetPosition().x) < 200.0f &&
 	   Abs(GetPosition().y - TheCamera.GetPosition().y) < 200.0f){
+#endif
 		float speedSq = m_vecMoveSpeed.MagnitudeSqr();
 		CVector smokeDir = 0.8f*m_vecMoveSpeed;
 		CVector smokePos;
@@ -335,6 +343,7 @@ CBoat::ProcessControl(void)
 			bIsDrowning = false;
 		}
 
+		// Apply buoyancy impulse the first time (why twice?)
 		m_fVolumeUnderWater = mod_Buoyancy.m_volumeUnderWater;
 		m_vecBuoyancePoint = buoyancePoint;
 		if(GetModelIndex() == MI_SKIMMER && GetUp().z < -0.5f && Abs(m_vecMoveSpeed.x) < 0.2f && Abs(m_vecMoveSpeed.y) < 0.2f)
@@ -344,13 +353,17 @@ CBoat::ProcessControl(void)
 		if(bSeparateTurnForce)
 			ApplyTurnForce(0.4f*buoyanceImpulse, buoyancePoint);
 
-		// TODO: what is this?
 		if(GetModelIndex() == MI_SKIMMER)
 			if(m_skimmerThingTimer != 0.0f ||
 			   GetForward().z < -0.5f && GetUp().z > -0.5f && m_vecMoveSpeed.z < -0.15f &&
 			   buoyanceImpulse.z > 0.01f*m_fMass * GRAVITY*CTimer::GetTimeStep() &&
 			   buoyanceImpulse.z < 0.4f*m_fMass * GRAVITY*CTimer::GetTimeStep()){
+#ifdef FIX_BUGS
+				// buoyanceImpulse already has a factor of timestep in it
+				float turnImpulse = -0.00017f*GetForward().z*buoyanceImpulse.z * m_fMass*CTimer::GetDefaultTimeStep();
+#else
 				float turnImpulse = -0.00017f*GetForward().z*buoyanceImpulse.z * m_fMass*CTimer::GetTimeStep();
+#endif
 				ApplyTurnForce(turnImpulse*GetForward(), GetUp());
 				bBoatInWater = false;
 				//BUG? aren't we forgetting the timestep here?
@@ -362,15 +375,21 @@ CBoat::ProcessControl(void)
 					m_skimmerThingTimer = 0.0f;
 			}
 
+		// Apply buoyancy impulse the second time (why twice?)
 		if(!onLand && bBoatInWater && GetUp().z > 0.0f){
+#ifdef FIX_BUGS
+			// buoyanceImpulse already has a factor of timestep in it
+			float impulse = m_vecMoveSpeed.MagnitudeSqr()*pBoatHandling->fAqPlaneForce*buoyanceImpulse.z*CTimer::GetDefaultTimeStep()*0.5f;
+#else
 			float impulse = m_vecMoveSpeed.MagnitudeSqr()*pBoatHandling->fAqPlaneForce*buoyanceImpulse.z*CTimer::GetTimeStep()*0.5f;
+#endif
 			if(GetModelIndex() == MI_SKIMMER)
 				impulse *= 1.0f + m_fGasPedal;
 			else if(m_fGasPedal > 0.05f)
 				impulse *= m_fGasPedal;
 			else
 				impulse = 0.0f;
-			impulse = Min(impulse, GRAVITY*pBoatHandling->fAqPlaneLimit*m_fMass*CTimer::GetTimeStep());
+			impulse = Min(impulse, GRAVITY*pBoatHandling->fAqPlaneLimit*m_fMass*CTimer::GetTimeStep());  // Both sides have a factor of TimeStep, therefore this Min() is not a problem at high FPS
 			ApplyMoveForce(impulse*GetUp());
 			ApplyTurnForce(impulse*GetUp(), buoyancePoint - pBoatHandling->fAqPlaneOffset*GetForward());
 		}
@@ -378,7 +397,11 @@ CBoat::ProcessControl(void)
 		// Handle boat moving forward
 		float fwdSpeed = 1.0f;
 		if(Abs(m_fGasPedal) > 0.05f || (fwdSpeed = m_vecMoveSpeed.Magnitude2D()) > 0.01f){
+#ifdef FIX_BUGS
+			if(bBoatInWater && fwdSpeed > 0.05f && CTimer::GetLogicalFramesPassed()) // Fix super-short wake trail at high FPS
+#else
 			if(bBoatInWater && fwdSpeed > 0.05f)
+#endif
 				AddWakePoint(GetPosition());
 
 			float steerFactor = 1.0f;
@@ -433,7 +456,11 @@ CBoat::ProcessControl(void)
 
 					// Spray some particles
 					CVector jetDir = -0.04f * force;
+#ifdef FIX_BUGS
+					if(m_fGasPedal > 0.0f && CTimer::GetLogicalFramesPassed()){  // Fix high-FPS particle spam
+#else
 					if(m_fGasPedal > 0.0f){
+#endif
 						if(GetStatus() == STATUS_PLAYER){
 							CVector sternPos = GetColModel()->boundingBox.min;
 							sternPos.x = 0.0f;
@@ -475,7 +502,11 @@ CBoat::ProcessControl(void)
 					CVector propellerForce = propellerDepth * Multiply3x3(GetMatrix(), force*CVector(-steerSin, 0.0f, 0.0f));
 					ApplyMoveForce(propellerForce * CTimer::GetTimeStep());
 					ApplyTurnForce(propellerForce * CTimer::GetTimeStep(), propeller);
+#ifdef FIX_BUGS
+					float rightForce = -steerSin * force * 0.75f/steerFactor * CTimer::GetTimeStep();
+#else
 					float rightForce = -steerSin * force * 0.75f/steerFactor * Max(CTimer::GetTimeStep(), 0.01f);
+#endif
 					ApplyTurnForce(GetRight() * rightForce, GetUp());
 				}
 			}else
@@ -485,7 +516,12 @@ CBoat::ProcessControl(void)
 				CVector right = CrossProduct(GetForward(), CVector(0.0f, 0.0f, 1.0f));
 				float rightSpeed = DotProduct(m_vecMoveSpeed, right);
 				float impulse = 0.1f*pHandling->fSuspensionBias * m_fMass * m_fVolumeUnderWater * rightSpeed * CTimer::GetTimeStep();
+#ifdef FIX_BUGS
+				// Fix boat perf at high FPS: ensure both terms have a (correct) factor of timestep before doing subtraction
+				ApplyMoveForce(right * CTimer::GetTimeStepFix() - impulse * 0.3f * CVector(-right.y, right.x, 0.0f));
+#else
 				ApplyMoveForce(right                            - impulse * 0.3f * CVector(-right.y, right.x, 0.0f));
+#endif
 			}
 
 			if(GetStatus() == STATUS_PLAYER && CPad::GetPad(0)->GetHandBrake()){
@@ -503,25 +539,45 @@ CBoat::ProcessControl(void)
 		m_vecMoveSpeed.y = Min(m_vecMoveSpeed.y, -(GetPosition().y - (WORLD_MAX_Y-100.0f))*0.01f);	// north
 		m_vecMoveSpeed.y = Max(m_vecMoveSpeed.y, -(GetPosition().y - (WORLD_MIN_Y+100.0f))*0.01f);	// south
 
+		// Apply water resistance to linear movement
 		if(!onLand && bBoatInWater && !bSeparateTurnForce)
 			ApplyWaterResistance();
 
+		// Apply water resistance to rotation
 		if((GetModelIndex() != MI_SKIMMER || m_skimmerThingTimer == 0.0f) && !bSeparateTurnForce){
-			// No idea what exactly is going on here besides drag in YZ
+#ifdef FIX_BUGS
+			// Rockstar's attempts to make this framerate independent are totally wrong.
+			// Rules of thumb: 
+			//   - use Pow(x,time) if you multiply the result into the velocity
+			//   - use x*time if you add the result into the velocity
+			// We have to disable one of these Pow() methods and then add our own correction at the end.
+			float fxfake = Pow(pBoatHandling->vecTurnRes.x, CTimer::GetDefaultTimeStep());
+			float fy     = Pow(pBoatHandling->vecTurnRes.y, CTimer::GetTimeStep());
+			float fz     = Pow(pBoatHandling->vecTurnRes.z, CTimer::GetTimeStep());
+			m_vecTurnSpeed = Multiply3x3(m_vecTurnSpeed, GetMatrix());	// invert - to local space
+			float drag = 1.0f/(1000.0f * SQR(m_vecTurnSpeed.x) + 1.0f) * fxfake;
+			m_vecTurnSpeed.y *= fy;
+			m_vecTurnSpeed.z *= fz;
+			float forceUp = -(1.0f - drag) * m_vecTurnSpeed.x * m_fTurnMass;
+			m_vecTurnSpeed = Multiply3x3(GetMatrix(), m_vecTurnSpeed);	// back to world
+			CVector com = Multiply3x3(GetMatrix(), m_vecCentreOfMass);
+			ApplyTurnForce(forceUp*GetUp() * CTimer::GetTimeStepFix(), com + GetForward());
+#else
 			float fx = Pow(pBoatHandling->vecTurnRes.x, CTimer::GetTimeStep());
 			float fy = Pow(pBoatHandling->vecTurnRes.y, CTimer::GetTimeStep());
 			float fz = Pow(pBoatHandling->vecTurnRes.z, CTimer::GetTimeStep());
 			m_vecTurnSpeed = Multiply3x3(m_vecTurnSpeed, GetMatrix());	// invert - to local space
-			// TODO: figure this out
+			float drag = 1.0f/(1000.0f * SQR(m_vecTurnSpeed.x) + 1.0f) * fx;
-			float magic = 1.0f/(1000.0f * SQR(m_vecTurnSpeed.x) + 1.0f) * fx;
 			m_vecTurnSpeed.y *= fy;
 			m_vecTurnSpeed.z *= fz;
-			float forceUp = (magic - 1.0f) * m_vecTurnSpeed.x * m_fTurnMass;
+			float forceUp = (drag - 1.0f) * m_vecTurnSpeed.x * m_fTurnMass;
 			m_vecTurnSpeed = Multiply3x3(GetMatrix(), m_vecTurnSpeed);	// back to world
 			CVector com = Multiply3x3(GetMatrix(), m_vecCentreOfMass);
 			ApplyTurnForce(forceUp*GetUp(), com + GetForward());
+#endif
 		}
 
+
 		m_nDeltaVolumeUnderWater = (m_fVolumeUnderWater-m_fPrevVolumeUnderWater)*10000;
 
 		// Falling into water
@@ -539,6 +595,9 @@ CBoat::ProcessControl(void)
 				speedFwd *= -m_nDeltaVolumeUnderWater * 0.01f * pHandling->fBrakeBias;
 				CVector speed = speedFwd*GetForward() + CVector(0.0f, 0.0f, speedUp);
 				CVector splashImpulse = speed * m_fMass;
+#ifdef FIX_BUGS
+				splashImpulse *= CTimer::GetTimeStepFix();
+#endif
 				ApplyMoveForce(splashImpulse);
 				ApplyTurnForce(splashImpulse, buoyancePoint);
 			}
@@ -546,8 +605,15 @@ CBoat::ProcessControl(void)
 
 		// Splashes
 		float speed = m_vecMoveSpeed.Magnitude();
+#ifdef FIX_BUGS
+		if(speed > 0.05f && GetUp().x > 0.0f && !TheCamera.GetLookingForwardFirstPerson() && IsVisible() &&
+		   (AutoPilot.m_nCarMission != MISSION_CRUISE || (CTimer::GetFrameCounter()&2) == 0) &&
+		   CTimer::GetLogicalFramesPassed() ) // Fix particle spam at high FPS
+#else
 		if(speed > 0.05f && GetUp().x > 0.0f && !TheCamera.GetLookingForwardFirstPerson() && IsVisible() &&
-		   (AutoPilot.m_nCarMission != MISSION_CRUISE || (CTimer::GetFrameCounter()&2) == 0)){
+		   (AutoPilot.m_nCarMission != MISSION_CRUISE || (CTimer::GetFrameCounter()&2) == 0))
+#endif
+		{
 			CVector splashPos, splashDir;
 			float splashSize, front, waterLevel;
 
@@ -682,8 +748,14 @@ CBoat::ProcessControl(void)
 		}
 
 		// Spray waterdrops on screen
+#ifdef FIX_BUGS
 		if(TheCamera.GetLookingForwardFirstPerson() && FindPlayerVehicle() && FindPlayerVehicle()->IsBoat() &&
-		   m_nDeltaVolumeUnderWater > 0 && numWaterDropOnScreen < 20){
+		   m_nDeltaVolumeUnderWater > 0 && numWaterDropOnScreen < 20 && CTimer::GetLogicalFramesPassed()) // Fix particle spam at high FPS
+#else
+		if(TheCamera.GetLookingForwardFirstPerson() && FindPlayerVehicle() && FindPlayerVehicle()->IsBoat() &&
+		   m_nDeltaVolumeUnderWater > 0 && numWaterDropOnScreen < 20)
+#endif
+		{
 			CVector dropPos;
 			CVector dropDir(CGeneral::GetRandomNumberInRange(-0.25f, 0.25f), CGeneral::GetRandomNumberInRange(1.0f, 0.75f), 0.0f);
 
@@ -714,7 +786,13 @@ CBoat::ProcessControl(void)
 				numWaterDropOnScreen++;
 		}
 
-		if(m_fPrevVolumeUnderWater == 0.0f && m_fVolumeUnderWater > 0.0f && GetModelIndex() == MI_SKIMMER){
+#ifdef FIX_BUGS
+		if(m_fPrevVolumeUnderWater == 0.0f && m_fVolumeUnderWater > 0.0f && GetModelIndex() == MI_SKIMMER &&
+		CTimer::GetLogicalFramesPassed()) // Fix particle spam at high FPS
+#else
+		if(m_fPrevVolumeUnderWater == 0.0f && m_fVolumeUnderWater > 0.0f && GetModelIndex() == MI_SKIMMER)
+#endif
+		{
 			CVector splashDir(0.0f, 0.0f, 0.25f*speed);
 			CVector splashPos = GetPosition();
 			float level;
@@ -773,6 +851,18 @@ CBoat::ProcessControlInputs(uint8 pad)
 	m_fBrake += (CPad::GetPad(pad)->GetBrake()/255.0f - m_fBrake)*0.1f;
 	m_fBrake = Clamp(m_fBrake, 0.0f, 1.0f);
 
+#ifdef FIX_BUGS
+	// Fix accelerator control and steering control ramp rates at high FPS
+	if(m_fBrake < 0.05f){
+		m_fBrake = 0.0f;
+		m_fAccelerate += (CPad::GetPad(pad)->GetAccelerate()/255.0f - m_fAccelerate)*0.1f*CTimer::GetTimeStepFix();
+		m_fAccelerate = Clamp(m_fAccelerate, 0.0f, 1.0f);
+	}else
+		m_fAccelerate = -m_fBrake*0.3f;
+
+	m_fSteeringLeftRight += (-CPad::GetPad(pad)->GetSteeringLeftRight()/128.0f - m_fSteeringLeftRight)*0.2f*CTimer::GetTimeStepFix();
+	m_fSteeringLeftRight = Clamp(m_fSteeringLeftRight, -1.0f, 1.0f);
+#else
 	if(m_fBrake < 0.05f){
 		m_fBrake = 0.0f;
 		m_fAccelerate += (CPad::GetPad(pad)->GetAccelerate()/255.0f - m_fAccelerate)*0.1f;
@@ -782,6 +872,7 @@ CBoat::ProcessControlInputs(uint8 pad)
 
 	m_fSteeringLeftRight += (-CPad::GetPad(pad)->GetSteeringLeftRight()/128.0f - m_fSteeringLeftRight)*0.2f;
 	m_fSteeringLeftRight = Clamp(m_fSteeringLeftRight, -1.0f, 1.0f);
+#endif
 
 	float steeringSq = m_fSteeringLeftRight < 0.0f ? -SQR(m_fSteeringLeftRight) : SQR(m_fSteeringLeftRight);
 	m_fSteerAngle = pHandling->fSteeringLock * DEGTORAD(steeringSq);
@@ -793,6 +884,82 @@ float fSeaPlaneWaterResistance = 30.0f;
 void
 CBoat::ApplyWaterResistance(void)
 {
+#ifdef FIX_BUGS
+	// TODO: confirm if the explanation below makes sense
+	float depthResistance = 0.001f * pHandling->fSuspensionForceLevel * SQR(m_fVolumeUnderWater) * m_fMass;
+	if(GetModelIndex() == MI_SKIMMER)
+		depthResistance *= fSeaPlaneWaterResistance;
+	float fwdSpeed = DotProduct(GetMoveSpeed(), GetForward());
+
+	// Water resistances goes up with the square of boat speed (in real life it goes up by the
+	// cube? close enough!).  An extra 0.05f fudge factor was probably put in to make sure the
+	// boat still has resistance at low speeds (ie auto-brakes to standstill).
+	float waterResistance = (SQR(fwdSpeed) + 0.05f) * Abs(depthResistance);  // Abs() used defensively, negative numbers stuff things up later
+	// waterResistance will now be a small number like 0.002 or 0.015
+
+	// An odd use of Abs() was in the original binary.  It's possible that the developers did not
+	// put this in intentionally, instead the compiler may have silently added it to avoid
+	// Pow() having to deal	with negative numbers to a fractional power (undefined) later.
+	// Regardless it was done badly, making assumptions like vecMoveRes never accidentally
+	// being negative, so the use of Abs() has changed a little bit in this FIX_BUGS.  In
+	// real gameplay these corner cases should rarely (never?) be encountered anyway.
+
+	// Our boat has different water resistances when travelling forwards (y axis) versus
+	// sideways (x axis).  Boats tend to find it hard to move sideways.
+	float rx = Abs(pBoatHandling->vecMoveRes.x/(waterResistance + 1.0f)); // Abs() used defensively, negative numbers stuff things up later
+	float ry = Abs(pBoatHandling->vecMoveRes.y/(waterResistance + 1.0f));
+	float rz = Abs(pBoatHandling->vecMoveRes.z/(waterResistance + 1.0f));
+	// These rx, ry, rz resistance numbers will each be something like 0.8 or 0.9 or so
+
+	// Fun fact: the above equations are _approximately_ the same as:
+	//
+	//         pBoatHandling->vecMoveRes.x * (1.0f - waterResistance)
+	//
+	// If you change the equations to this then boating feels about the same in-game.
+	// Which version makes more sense compared to physics in real life?  Probably neither :P
+	// This second version of the equation is a little more efficient however (no division).
+
+	// Now how do we apply these rx ry rz resistance numbers to the boat speed?
+	// It's not simple:
+	//
+	//  - We can't multiply them into the speed once per frame, because then players with
+	//    higher framerates will get a lot more friction when boating (lower top speed).
+	//
+	//  - We can't linearly modify each r number based off frametime, as higher FPS players
+	//    will still end up with more friction.  This is for the same reason why linearly
+	//    reducing your bank account's yearly interest into monthly amounts but then
+	//    compounding it monthly will yield you more money than just compounding it yearly.
+	//
+	//  - We could try compounding each r number based off how many fixed units of time have
+	//    passed (eg multiply itself by itself for every 1ms elapsed this frame).  This will
+	//    work fairly regardless of framerate.
+	//
+	// We don't actually have to limit ourselves to a fixed time unit (like 1ms chunks),
+	// instead we can raise the resistance to some power of time using Pow().
+	float rrx     = Pow(rx, 0.5f*CTimer::GetTimeStep());  // Why 0.5f?  Taste?
+	float rry     = Pow(ry, 0.5f*CTimer::GetTimeStep());
+	float rrz     = Pow(rz, 0.5f*CTimer::GetTimeStep());
+	float rryfake = Pow(ry, 0.5f*CTimer::GetDefaultTimeStep());  // Fudge factor needed for other equations to make sense at high FPS
+
+	m_vecMoveSpeed = Multiply3x3(m_vecMoveSpeed, GetMatrix());	// convert velocities to boat-local space (y = boat forwards, x = sideways, z = up/down)
+	m_vecMoveSpeed.x *= rrx;
+	m_vecMoveSpeed.y *= rry;
+	m_vecMoveSpeed.z *= rrz;
+	float force = (rryfake - 1.0f) * m_vecMoveSpeed.y * m_fMass;
+	m_vecMoveSpeed = Multiply3x3(GetMatrix(), m_vecMoveSpeed);	// back to world space
+
+	// WTH is this for?
+	ApplyTurnForce(force*GetForward()*CTimer::GetTimeStepFix(), -GetUp());
+
+	// What the hell?  Why arbitrarily compound in one more factor of rrz?
+	// This is framerate dependent!  Bah!  I suspect it has very little effect.
+	/*
+	if(m_vecMoveSpeed.z > 0.0f)
+		m_vecMoveSpeed.z *= rrz;
+	else
+		m_vecMoveSpeed.z *= (1.0f - rrz)*0.5f + rrz;
+	*/
+#else
 	// TODO: figure out how this works
 	float resistance = 0.001f * pHandling->fSuspensionForceLevel * SQR(m_fVolumeUnderWater) * m_fMass;
 	if(GetModelIndex() == MI_SKIMMER)
@@ -817,6 +984,7 @@ CBoat::ApplyWaterResistance(void)
 		m_vecMoveSpeed.z *= fz;
 	else
 		m_vecMoveSpeed.z *= (1.0f - fz)*0.5f + fz;
+#endif
 }
 
 RwObject*

src/vehicles/Floater.cpp

@@ -109,6 +109,17 @@ cBuoyancy::ProcessBuoyancyBoat(CVehicle *veh, float buoyancy, CVector *point, CV
 				float volume = SimpleSumBuoyancyData(waterLevel, waterPosition);
 				float upImpulse = volume * volDiv * buoyancy * CTimer::GetTimeStep();
 				CVector speed = veh->GetSpeed(Multiply3x3(veh->GetMatrix(), CVector(x, y, 0.0f)));
+#ifdef FIX_BUGS
+				// "GetSpeed" seems to depend on framerate (bad).
+				// This ruins boat performance at high FPS.  Approximate sequence of events:
+				//  - "speed" goes tiny at high FPS
+				//  - "damp" goes high as a result
+				//  - high dampening reduces the buoyancy forces that keep the boat above the water
+				//  - boats sit _slightly_ lower in water (you have to disable ALL waves to see this, it's a very small change)
+				//  - all of boat handling performance changes because a different amount of the boat is underwater
+				// Finding this was a PITA!
+				speed /= CTimer::GetTimeStepFix();
+#endif
 				float damp = 1.0f - DotProduct(speed, waterNormal)*veh->pHandling->fSuspensionDampingLevel;
 				float finalImpulse = upImpulse*Max(damp, 0.0f);
 				impulse->z += finalImpulse;

src/vehicles/Transmission.cpp

@@ -55,6 +55,8 @@ cTransmission::CalculateGearForSimpleCar(float speed, uint8 &gear)
 	}
 }
 
+/* This function causes 'pulsing' of throttle when reversing at max speed.  You
+ * can most easily observe this when the framelimiter is enabled.*/
 float
 cTransmission::CalculateDriveAcceleration(const float &gasPedal, uint8 &gear, float &time, const float &velocity, bool cheat)
 {
@@ -123,7 +125,12 @@ cTransmission::CalculateDriveAcceleration(const float &gasPedal, uint8 &gear, fl
 	float targetVelocity = Gears[gear].fMaxVelocity*speedMul*fCheat;
 	float accel = (targetVelocity - fVelocity) * (fEngineAcceleration*accelMul) / Abs(targetVelocity);
 	if(Abs(fVelocity) < Abs(Gears[gear].fMaxVelocity*fCheat))
+#ifdef FIX_BUGS
+		// The acceleration provided by a transmission+engine should not depend on framelength.
+		fAcceleration = gasPedal * accel;
+#else
 		fAcceleration = gasPedal * accel * CTimer::GetTimeStep();
+#endif
 	else
 		fAcceleration = 0.0f;
 	return fAcceleration;

src/vehicles/Vehicle.cpp

@@ -126,6 +126,9 @@ CVehicle::CVehicle(uint8 CreatedBy)
 	m_nCarHornTimer = 0;
 	m_nCarHornPattern = 0;
 	m_nCarHornDelay = 0;
+#ifdef FIX_BUGS
+	m_fCarHornTimeButtonLastHit = 0.0f;
+#endif
 	bPartOfConvoy = false;
 	bHeliMinimumTilt = false;
 	bAudioChangingGear = false;
@@ -788,7 +791,14 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 	bAlreadySkidding = false;
 #endif
 
-	// how much force we want to apply in these axes
+	// Velocity impulses fwd and right.  Units are like meters per second.
+	// This function was written assuming a fixed FPS, so a correction is made
+	// right at the end before actually applying these impulses.
+	//
+	// Note that many functions in this engine deal with "force impulses" rather
+	// than "velocity impulses".  They are directly related: F=ma.  It is
+	// possible that the original devs actually used force impulses here but
+	// an optimising compiler re-arranged their maths.
 	float fwd = 0.0f;
 	float right = 0.0f;
 
@@ -804,7 +814,12 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 		bAlreadySkidding = true;
 	*wheelState = WHEEL_STATE_NORMAL;
 
+#ifdef FIX_BUGS
+	// Everything else here is timestep independent, let's stay with this theme to keep the rest of the FPS bugfixes simpler.
+	adhesion *= CTimer::GetDefaultTimeStep();
+#else
 	adhesion *= CTimer::GetTimeStep();
+#endif
 	if(bAlreadySkidding)
 		adhesion *= pHandling->fTractionLoss;
 
@@ -812,12 +827,6 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 	if(contactSpeedRight != 0.0f){
 		// exert opposing force
 		right = -contactSpeedRight/wheelsOnGround;
-		// BUG?
-		// contactSpeedRight is independent of framerate but right has timestep as a factor
-		// so we probably have to fix this
-		// fixing this causes jittery cars at 15fps, and causes the car to move backwards slowly at 18fps
-		// at 19fps, the effects are gone ...
-		//right *= CTimer::GetTimeStepFix();
 
 		if(wheelStatus == WHEEL_STATUS_BURST){
 			float fwdspeed = Min(contactSpeedFwd, fBurstSpeedMax);
@@ -828,7 +837,7 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 	if(bDriving){
 		fwd = thrust;
 
-		// limit sideways force (why?)
+		// Limit sideways forces applied by the tires to the max the tires can possibly do.
 		if(right > 0.0f){
 			if(right > adhesion)
 				right = adhesion;
@@ -838,11 +847,6 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 		}
 	}else if(contactSpeedFwd != 0.0f){
 		fwd = -contactSpeedFwd/wheelsOnGround;
-#ifdef FIX_BUGS
-		// contactSpeedFwd is independent of framerate but fwd has timestep as a factor
-		// so we probably have to fix this
-		fwd *= CTimer::GetTimeStepFix();
-#endif
 
 		if(!bBraking){
 			if(m_fGasPedal < 0.01f){
@@ -854,9 +858,6 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 					brake = 0.2f * mod_HandlingManager.fWheelFriction / pHandling->fMass;
 				else
 					brake = mod_HandlingManager.fWheelFriction / pHandling->fMass;
-#ifdef FIX_BUGS
-				brake *= CTimer::GetTimeStepFix();
-#endif
 			}
 		}
 
@@ -883,10 +884,10 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 				*wheelState = WHEEL_STATE_SKIDDING;
 		}
 
-		float l = Sqrt(speedSq);
+		float speed = Sqrt(speedSq);
 		float tractionLoss = bAlreadySkidding ? 1.0f : pHandling->fTractionLoss;
-		right *= adhesion * tractionLoss / l;
+		right *= adhesion * tractionLoss / speed;
-		fwd *= adhesion * tractionLoss / l;
+		fwd   *= adhesion * tractionLoss / speed;
 	}
 
 	if(fwd != 0.0f || right != 0.0f){
@@ -918,9 +919,19 @@ CVehicle::ProcessWheel(CVector &wheelFwd, CVector &wheelRight, CVector &wheelCon
 		else
 			turnDirection = direction;
 
+
+		// Curious: there is a perfectly good ApplyMoveSpeed() function that 
+		// takes "velocity impulses", but instead we use the ApplyMoveForce() 
+		// function which takes a "force impulse" instead and then fix up the
+		// difference by multiplying in the vehicle mass (F=ma).  Possibly 
+		// evidence that an optimising compiler re-arranged the arithmetic?
 		float impulse = speed*m_fMass;
 		float turnImpulse = turnSpeed*GetMass(wheelContactPoint, turnDirection);
 
+#ifdef FIX_BUGS
+		impulse     = impulse     * CTimer::GetTimeStepFix();
+		turnImpulse = turnImpulse * CTimer::GetTimeStepFix();
+#endif
 		ApplyMoveForce(impulse * direction);
 		ApplyTurnForce(turnImpulse * turnDirection, wheelContactPoint);
 	}
@@ -944,7 +955,14 @@ CVehicle::ProcessBikeWheel(CVector &wheelFwd, CVector &wheelRight, CVector &whee
 	bAlreadySkidding = false;
 #endif
 
-	// how much force we want to apply in these axes
+	// Velocity impulses fwd and right.  Units are like meters per second.
+	// This function was written assuming a fixed FPS, so a correction is made
+	// right at the end before actually applying these impulses.
+	//
+	// Note that many functions in this engine deal with "force impulses" rather
+	// than "velocity impulses".  They are directly related: F=ma.  It is
+	// possible that the original devs actually used force impulses here but
+	// an optimising compiler re-arranged their maths.
 	float fwd = 0.0f;
 	float right = 0.0f;
 
@@ -961,7 +979,12 @@ CVehicle::ProcessBikeWheel(CVector &wheelFwd, CVector &wheelRight, CVector &whee
 		bAlreadySkidding = true;
 	*wheelState = WHEEL_STATE_NORMAL;
 
+#ifdef FIX_BUGS
+	// Everything else here is timestep independent, let's stay with this theme to keep the rest of the FPS bugfixes simpler.
+	adhesion *= CTimer::GetDefaultTimeStep();
+#else
 	adhesion *= CTimer::GetTimeStep();
+#endif
 	if(bAlreadySkidding)
 		adhesion *= pHandling->fTractionLoss;
 
@@ -974,11 +997,6 @@ CVehicle::ProcessBikeWheel(CVector &wheelFwd, CVector &wheelRight, CVector &whee
 	if(contactSpeedRight != 0.0f){
 		// exert opposing force
 		right = -contactSpeedRight/wheelsOnGround;
-#ifdef FIX_BUGS
-		// contactSpeedRight is independent of framerate but right has timestep as a factor
-		// so we probably have to fix this
-		right *= CTimer::GetTimeStepFix();
-#endif
 
 		if(wheelStatus == WHEEL_STATUS_BURST){
 			float fwdspeed = Min(contactSpeedFwd, fBurstBikeSpeedMax);		
@@ -999,12 +1017,6 @@ CVehicle::ProcessBikeWheel(CVector &wheelFwd, CVector &wheelRight, CVector &whee
 		}
 	}else if(contactSpeedFwd != 0.0f){
 		fwd = -contactSpeedFwd/wheelsOnGround;
-#ifdef FIX_BUGS
-		// contactSpeedFwd is independent of framerate but fwd has timestep as a factor
-		// so we probably have to fix this
-		fwd *= CTimer::GetTimeStepFix();
-#endif
-
 		if(!bBraking){
 			if(m_fGasPedal < 0.01f){
 				if(IsBike())
@@ -1015,9 +1027,6 @@ CVehicle::ProcessBikeWheel(CVector &wheelFwd, CVector &wheelRight, CVector &whee
 					brake = 0.2f * mod_HandlingManager.fWheelFriction / m_fMass;
 				else
 					brake = mod_HandlingManager.fWheelFriction / m_fMass;
-#ifdef FIX_BUGS
-				brake *= CTimer::GetTimeStepFix();
-#endif
 			}
 		}
 
@@ -1068,6 +1077,10 @@ CVehicle::ProcessBikeWheel(CVector &wheelFwd, CVector &wheelRight, CVector &whee
 
 		float impulse = speed*m_fMass;
 		float turnImpulse = speed*GetMass(wheelContactPoint, direction);
+#ifdef FIX_BUGS
+		impulse     = impulse     * CTimer::GetTimeStepFix();
+		turnImpulse = turnImpulse * CTimer::GetTimeStepFix();
+#endif
 		CVector vTurnImpulse = turnImpulse * direction;
 		ApplyMoveForce(impulse * direction);
 

src/vehicles/Vehicle.h

@@ -273,6 +273,9 @@ public:
 	uint8 m_nCarHornPattern;
 	bool m_bSirenOrAlarm;
 	uint8 m_nCarHornDelay;
+#ifdef FIX_BUGS
+	float m_fCarHornTimeButtonLastHit;
+#endif
 	int8 m_comedyControlState;
 	CStoredCollPoly m_aCollPolys[2];     // poly which is under front/rear part of car
 	float m_fSteerInput;