Fix vehicle corona/shadow flicker on fogless to foggy weather blend (#4803)

ResyncInterpolationWithGameClock snapped CWeather::InterpolationValue
to minute/60, dropping the seconds component. CTimeCycle::CalcColoursForPoint
then blended m_CurrentColours per game-minute instead of per frame, so
m_fSpriteBrightness (vehicle coronas) and m_wShadowStrength (vehicle
shadows) ticked visibly when the game clock runs fast.

Match the value CWeather::Update derives at 0x72B897
(seconds/3600 + minutes/60) so the wrap-suppression still holds and
m_CurrentColours interpolates smoothly each frame.

Author: Zephkek

Client/game_sa/CWeatherSA.cpp

@@ -30,13 +30,20 @@ void CWeatherSA::ResyncInterpolationWithGameClock(unsigned char primary, unsigne
     // CWeather::InterpolationValue — see plugin_sa CWeather.cpp (0xC8130C)
     constexpr DWORD VAR_InterpolationValue = 0xC8130C;
     constexpr DWORD VAR_TimeMinutes = 0xB70152;
+    constexpr DWORD VAR_TimeSeconds = 0xB70150;
 
     if (primary == secondary)
         MemPutFast<float>(VAR_InterpolationValue, 0.0f);
     else
     {
+        // Match the value CWeather::Update derives at 0x72B897:
+        //   v0 = (seconds / 60 + minutes) / 60
+        // Snapping to minutes only would drop seconds and make CTimeCycle::CalcColoursForPoint
+        // step m_CurrentColours per game-minute, which surfaces as flicker on vehicle coronas
+        // (m_fSpriteBrightness) and shadows (m_wShadowStrength) when the clock runs fast.
         const auto  ucMinute = *reinterpret_cast<unsigned char*>(VAR_TimeMinutes);
-        const float fInterp = std::min(1.f, static_cast<float>(ucMinute) / 60.f);
+        const auto  ucSecond = *reinterpret_cast<unsigned char*>(VAR_TimeSeconds);
+        const float fInterp = std::min(1.f, static_cast<float>(ucMinute) / 60.f + static_cast<float>(ucSecond) / 3600.f);
         MemPutFast<float>(VAR_InterpolationValue, fInterp);
     }
 }

Client/mods/deathmatch/logic/CBlendedWeather.cpp

@@ -58,8 +58,9 @@ void CBlendedWeather::DoPulse()
 
     m_pWeather->Set(ucPrimary, ucSecondary);
     // CWeather::Update (before this pulse) advances InterpolationValue for its own Old/New pair.
-    // After we overwrite Old/New with MTA's state, keep the blend weight aligned with the game
-    // clock so reflective/translucent materials (e.g. glass windows) match the sky (#4803).
+    // After we overwrite Old/New with MTA's state, mirror the value CWeather::Update would derive
+    // (seconds/3600 + minutes/60) so CTimeCycle::CalcColoursForPoint blends m_CurrentColours
+    // smoothly per frame instead of stepping per game-minute (#4803).
     m_pWeather->ResyncInterpolationWithGameClock(ucPrimary, ucSecondary);
 }