3 files changed, 55 insertions, 11 deletions

diff --git a/src/control/Script.cpp b/src/control/Script.cpp
index af151802..5e7f4936 100644
--- a/src/control/Script.cpp
+++ b/src/control/Script.cpp
@@ -144,7 +144,7 @@ void CUpsideDownCarCheck::Init()
 bool CUpsideDownCarCheck::IsCarUpsideDown(int32 id)
 {
 	CVehicle* v = CPools::GetVehiclePool()->GetAt(id);
-	return v->GetMatrix().GetUp()->z <= -0.97f &&
+	return v->GetUp().z <= -0.97f &&
 		v->GetMoveSpeed().Magnitude() < 0.01f &&
 		v->GetTurnSpeed().Magnitude() < 0.02f;
 }
diff --git a/src/entities/Physical.cpp b/src/entities/Physical.cpp
index b7ca1904..600e5dca 100644
--- a/src/entities/Physical.cpp
+++ b/src/entities/Physical.cpp
@@ -304,6 +304,22 @@ CPhysical::RemoveRefsToEntity(CEntity *ent)
 	}
 }
 
+void
+CPhysical::PlacePhysicalRelativeToOtherPhysical(CPhysical *other, CPhysical *phys, CVector localPos)
+{
+	CVector worldPos = other->GetMatrix() * localPos;
+	float step = 0.9f * CTimer::GetTimeStep();
+	CVector pos = other->m_vecMoveSpeed*step + worldPos;
+
+	CWorld::Remove(phys);
+	phys->GetMatrix() = other->GetMatrix();
+	phys->GetPosition() = pos;
+	phys->m_vecMoveSpeed = other->m_vecMoveSpeed;
+	phys->GetMatrix().UpdateRW();
+	phys->UpdateRwFrame();
+	CWorld::Add(phys);
+}
+
 int32
 CPhysical::ProcessEntityCollision(CEntity *ent, CColPoint *colpoints)
 {
@@ -434,15 +450,38 @@ CPhysical::ApplyFrictionTurnForce(float jx, float jy, float jz, float px, float
 	m_vecTurnFriction += turnimpulse*(1.0f/m_fTurnMass);
 }
 
-void
-CPhysical::ApplySpringCollision(float f1, CVector &v, CVector &p, float f2, float f3)
+bool
+CPhysical::ApplySpringCollision(float springConst, CVector &springDir, CVector &point, float springRatio, float bias)
 {
-	if(1.0f - f2 <= 0.0f)
-		return;
+	float compression = 1.0f - springRatio;
+	if(compression > 0.0f){
+		float step = min(CTimer::GetTimeStep(), 3.0f);
+		float impulse = -0.008f*m_fMass*step * springConst * compression * bias*2.0f;
+		ApplyMoveForce(springDir*impulse);
+		ApplyTurnForce(springDir*impulse, point);
+	}
+	return true;
+}
+
+// What exactly is speed?
+bool
+CPhysical::ApplySpringDampening(float damping, CVector &springDir, CVector &point, CVector &speed)
+{
+	float speedA = DotProduct(speed, springDir);
+	float speedB = DotProduct(GetSpeed(point), springDir);
 	float step = min(CTimer::GetTimeStep(), 3.0f);
-	float strength = -0.008f*m_fMass*2.0f*step * f1 * (1.0f-f2) * f3;
-	ApplyMoveForce(v*strength);
-	ApplyTurnForce(v*strength, p);
+	float impulse = -damping * (speedA + speedB)/2.0f * m_fMass * step * 0.53f;
+
+	// what is this?
+	float a = m_fTurnMass / ((point.MagnitudeSqr() + 1.0f) * 2.0f * m_fMass);
+	a = min(a, 1.0f);
+	float b = fabs(impulse / (speedB * m_fMass));
+	if(a < b)
+		impulse *= a/b;
+
+	ApplyMoveForce(springDir*impulse);
+	ApplyTurnForce(springDir*impulse, point);
+	return true;
 }
 
 void
@@ -1909,6 +1948,7 @@ STARTPATCHES
 	InjectHook(0x4970C0, &CPhysical::AddCollisionRecord_Treadable, PATCH_JUMP);
 	InjectHook(0x497240, &CPhysical::GetHasCollidedWith, PATCH_JUMP);
 	InjectHook(0x49F820, &CPhysical::RemoveRefsToEntity, PATCH_JUMP);
+	InjectHook(0x49F890, &CPhysical::PlacePhysicalRelativeToOtherPhysical, PATCH_JUMP);
 
 #define F3 float, float, float
 	InjectHook(0x495B10, &CPhysical::ApplyMoveSpeed, PATCH_JUMP);
@@ -1918,6 +1958,7 @@ STARTPATCHES
 	InjectHook(0x495D90, (void (CPhysical::*)(F3))&CPhysical::ApplyFrictionMoveForce, PATCH_JUMP);
 	InjectHook(0x495E10, (void (CPhysical::*)(F3, F3))&CPhysical::ApplyFrictionTurnForce, PATCH_JUMP);
 	InjectHook(0x499890, &CPhysical::ApplySpringCollision, PATCH_JUMP);
+	InjectHook(0x499990, &CPhysical::ApplySpringDampening, PATCH_JUMP);
 	InjectHook(0x495B50, &CPhysical::ApplyGravity, PATCH_JUMP);
 	InjectHook(0x495B80, (void (CPhysical::*)(void))&CPhysical::ApplyFriction, PATCH_JUMP);
 	InjectHook(0x495C20, &CPhysical::ApplyAirResistance, PATCH_JUMP);
diff --git a/src/entities/Physical.h b/src/entities/Physical.h
index 0104268a..81d3d649 100644
--- a/src/entities/Physical.h
+++ b/src/entities/Physical.h
@@ -81,6 +81,7 @@ public:
 	void AddCollisionRecord_Treadable(CEntity *ent);
 	bool GetHasCollidedWith(CEntity *ent);
 	void RemoveRefsToEntity(CEntity *ent);
+	static void PlacePhysicalRelativeToOtherPhysical(CPhysical *other, CPhysical *phys, CVector localPos);
 
 	float GetDistanceSq(void) { return m_vecMoveSpeed.MagnitudeSqr() * sq(CTimer::GetTimeStep()); }
 	// get speed of point p relative to entity center
@@ -104,8 +105,8 @@ public:
 		bIsInSafePosition = false;	
 	}
 
-	const CVector& GetMoveSpeed() { return m_vecMoveSpeed; }
-	const CVector& GetTurnSpeed() { return m_vecTurnSpeed; }
+	const CVector &GetMoveSpeed() { return m_vecMoveSpeed; }
+	const CVector &GetTurnSpeed() { return m_vecTurnSpeed; }
 
 	void ApplyMoveSpeed(void);
 	void ApplyTurnSpeed(void);
@@ -120,7 +121,9 @@ public:
 	void ApplyFrictionMoveForce(const CVector &j) { ApplyFrictionMoveForce(j.x, j.y, j.z); }
 	void ApplyFrictionTurnForce(float jx, float jy, float jz, float rx, float ry, float rz);
 	void ApplyFrictionTurnForce(const CVector &j, const CVector &p) { ApplyFrictionTurnForce(j.x, j.y, j.z, p.x, p.y, p.z); }
-	void ApplySpringCollision(float f1, CVector &v, CVector &p, float f2, float f3);
+	// springRatio: 1.0 fully extended, 0.0 fully compressed
+	bool ApplySpringCollision(float springConst, CVector &springDir, CVector &point, float springRatio, float bias);
+	bool ApplySpringDampening(float damping, CVector &springDir, CVector &point, CVector &speed);
 	void ApplyGravity(void);
 	void ApplyFriction(void);
 	void ApplyAirResistance(void);