Tweak wheel scaling behavior to be more consistent (#1650)

* Tweak wheel scaling behavior to be more consistent

* Handle m_pUpgrades being nullptr in CClientVehicle::ResetWheelScale

m_pUpgrades shouldn't be null unless its allocation during the
constructor fails without throwing an exception, but other functions
in the same file check for null before using m_pUpgrades, so add a
check here too to be safe.

* Revert "Handle m_pUpgrades being nullptr in CClientVehicle::ResetWheelScale"

This reverts commit b0880ad.

Checking for nullptr here actually is probably overly defensive, as the
new operator that allocates this field may throw an exception. I think
it is better to be a bit offensive here, because if m_pUpgrades becomes
null something is going very wrong.

* Assert that m_pUpgrades is not null in CClientVehicle::ResetWheelScale

As explained in previous commits, if the software behaves as specified,
checking for m_pUpgrades is not necessary. Instead, check that invariant
is being held via an assertion, which only impacts debug builds. This
may be useful to catch errors if the `CClientVehicle` class is extended
in such a way that a subclass sets m_pUpgrades to nullptr.

* Address suggested change by @qaisjp

* Restore m_fWheelScale in CClientVehicle::Create if needed

Restoring m_fWheelScale to fPreviousWheelScale is needed to handle
succesive restreams properly.

Author: AlexTMjugador

Client/mods/deathmatch/logic/CClientVehicle.cpp

@@ -171,6 +171,9 @@ CClientVehicle::CClientVehicle(CClientManager* pManager, ElementID ID, unsigned
 
     // We've not yet been streamed in
     m_bJustStreamedIn = false;
+
+    // We've not changed the wheel scale
+    m_bWheelScaleChanged = false;
 }
 
 CClientVehicle::~CClientVehicle()
@@ -2682,7 +2685,6 @@ void CClientVehicle::Create()
         m_pVehicle->SetGravity(&m_vecGravity);
         m_pVehicle->SetHeadLightColor(m_HeadLightColor);
         m_pVehicle->SetRadioStatus(0);
-        m_pVehicle->SetWheelScale(m_fWheelScale);
 
         if (IsNitroInstalled())
         {
@@ -2825,10 +2827,24 @@ void CClientVehicle::Create()
             if (m_bHasCustomHandling)
                 ApplyHandling();
         }
+
+        // Applying wheel upgrades can change these values.
+        // We should keep track of the original values to restore them
+        bool  bPreviousWheelScaleChanged = m_bWheelScaleChanged;
+        float fPreviousWheelScale = m_fWheelScale;
+
         // Re-add all the upgrades - Has to be applied after handling *shrugs*
         if (m_pUpgrades)
             m_pUpgrades->ReAddAll();
 
+        // Restore custom wheel scale
+        if (bPreviousWheelScaleChanged)
+        {
+            m_pVehicle->SetWheelScale(fPreviousWheelScale);
+            m_fWheelScale = fPreviousWheelScale;
+            m_bWheelScaleChanged = true;
+        }
+
         if (m_ComponentData.empty())
         {
             // grab our map of components
@@ -4992,6 +5008,8 @@ void CClientVehicle::SetWheelScale(float fWheelScale)
         m_pVehicle->SetWheelScale(fWheelScale);
     }
     m_fWheelScale = fWheelScale;
+
+    m_bWheelScaleChanged = true;
 }
 
 float CClientVehicle::GetWheelScale()
@@ -5002,3 +5020,19 @@ float CClientVehicle::GetWheelScale()
     }
     return m_fWheelScale;
 }
+
+// This function is meant to be called after GTA resets wheel scale
+// (i.e. after installing a wheel upgrade)
+void CClientVehicle::ResetWheelScale()
+{
+    assert(m_pUpgrades);
+
+    // The calculation of the default wheel scale is based on original GTA code at functions
+    // 0x6E3290 (CVehicle::AddVehicleUpgrade) and 0x6DF930 (CVehicle::RemoveVehicleUpgrade)
+    if (m_pUpgrades->GetSlotState(12) != 0)
+        m_fWheelScale = m_pModelInfo->GetVehicleWheelSize(eResizableVehicleWheelGroup::FRONT_AXLE);
+    else
+        m_fWheelScale = 1.0f;
+
+    m_bWheelScaleChanged = false;
+}

Client/mods/deathmatch/logic/CClientVehicle.h

@@ -496,6 +496,7 @@ class CClientVehicle : public CClientStreamElement
 
     float GetWheelScale();
     void  SetWheelScale(float fWheelScale);
+    void  ResetWheelScale();
 
     bool OnVehicleFallThroughMap();
 
@@ -621,6 +622,7 @@ class CClientVehicle : public CClientStreamElement
     float m_fTrainPosition;
     uchar m_ucTrackID;
     bool  m_bJustStreamedIn;
+    bool  m_bWheelScaleChanged;
 
     // Time dependent error compensation interpolation
     struct

Client/mods/deathmatch/logic/CVehicleUpgrades.cpp

@@ -611,6 +611,10 @@ void CVehicleUpgrades::ForceAddUpgrade(unsigned short usUpgrade)
 
         // Add it to the slot
         m_SlotStates[ucSlot] = usUpgrade;
+
+        // Reset wheel scale if it is a wheel upgrade
+        if (ucSlot == 12)
+            m_pVehicle->ResetWheelScale();
     }
 }
 
@@ -656,6 +660,10 @@ bool CVehicleUpgrades::RemoveUpgrade(unsigned short usUpgrade)
                 m_SlotStates[ucSlot] = 0;
             }
 
+            // Reset wheel scale if it is a wheel upgrade
+            if (ucSlot == 12)
+                m_pVehicle->ResetWheelScale();
+
             return true;
         }
     }
@@ -710,6 +718,10 @@ void CVehicleUpgrades::RemoveAll(bool bRipFromVehicle)
                 }
             }
             m_SlotStates[ucSlot] = 0;
+
+            // Reset wheel scale for wheel upgrades
+            if (ucSlot == 12 && m_pVehicle)
+                m_pVehicle->ResetWheelScale();
         }
     }
 }