Fix explosion knockback issues and tweak knockback strength (#4590)

src/ChunkMap.cpp

@@ -1313,18 +1313,19 @@ void cChunkMap::DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_
 				a_Entity.TakeDamage(dtExplosion, nullptr, static_cast<int>((1 / std::max(1.0, DistanceFromExplosion.Length())) * 8 * ExplosionSizeInt), 0);
 			}
 
-			double Length = DistanceFromExplosion.Length();
+			float EntityExposure = a_Entity.GetExplosionExposureRate(ExplosionPos, static_cast<float>(a_ExplosionSize));
-			if (Length <= ExplosionSizeInt)  // Entity is impacted by explosion
+
+			// Exposure reduced by armor
+			EntityExposure = EntityExposure * (1.0f - a_Entity.GetEnchantmentBlastKnockbackReduction());
+
+			auto Impact = std::pow(std::max(0.2, DistanceFromExplosion.Length()), -1);
+			Impact *= EntityExposure * ExplosionSizeInt * 6.0;
+
+			if (Impact > 0.0)
 			{
-				float EntityExposure = a_Entity.GetExplosionExposureRate(ExplosionPos, static_cast<float>(a_ExplosionSize));
-
-				// Exposure reduced by armor
-				EntityExposure = EntityExposure * (1.0f - a_Entity.GetEnchantmentBlastKnockbackReduction());
-
-				double Impact = (1 - ((Length / ExplosionSizeInt) / 2)) * EntityExposure;
-
 				DistanceFromExplosion.Normalize();
-				DistanceFromExplosion *= Impact;
+				DistanceFromExplosion *= Vector3d{Impact, 0.0, Impact};
+				DistanceFromExplosion.y += 0.3 * Impact;
 
 				a_Entity.SetSpeed(DistanceFromExplosion);
 			}
@@ -2315,8 +2316,3 @@ void cChunkMap::DelChunkStay(cChunkStay & a_ChunkStay)
 	}  // for itr - Chunks[]
 	a_ChunkStay.OnDisabled();
 }
-
-
-
-
-

src/Entities/Player.cpp

@@ -3080,7 +3080,7 @@ float cPlayer::GetExplosionExposureRate(Vector3d a_ExplosionPosition, float a_Ex
 		return 0;  // No impact from explosion
 	}
 
-	return super::GetExplosionExposureRate(a_ExplosionPosition, a_ExlosionPower);
+	return super::GetExplosionExposureRate(a_ExplosionPosition, a_ExlosionPower) / 30.0f;
 }
 
 

src/Entities/Player.h

@@ -581,6 +581,9 @@ public:
 	Otherwise it returns the dig speed (float GetDigSpeed(BLOCKTYPE a_Block)) divided by the block hardness (cBlockInfo::GetHardness(BLOCKTYPE a_Block)) divided by 30 if the player can harvest the block and divided by 100 if he can't. */
 	float GetPlayerRelativeBlockHardness(BLOCKTYPE a_Block);
 
+	/** get player explosion exposure rate */
+	virtual float GetExplosionExposureRate(Vector3d a_ExplosionPosition, float a_ExlosionPower) override;
+
 protected:
 
 	typedef std::vector<std::vector<AString> > AStringVectorVector;
@@ -759,9 +762,6 @@ protected:
 	/** Returns the filename for the player data based on the UUID given.
 	This can be used both for online and offline UUIDs. */
 	AString GetUUIDFileName(const cUUID & a_UUID);
-
-	/** get player explosion exposure rate */
-	virtual float GetExplosionExposureRate(Vector3d a_ExplosionPosition, float a_ExlosionPower) override;
 private:
 
 	/** Pins the player to a_Location until Unfreeze() is called.

src/World.cpp

@@ -1417,17 +1417,20 @@ void cWorld::DoExplosionAt(double a_ExplosionSize, double a_BlockX, double a_Blo
 
 	BroadcastSoundEffect("entity.generic.explode", Vector3d(a_BlockX, a_BlockY, a_BlockZ), 4.0f, SoundPitchMultiplier * 0.7f);
 
+	Vector3d ExplosionPos(a_BlockX, a_BlockY, a_BlockZ);
 	{
 		cCSLock Lock(m_CSPlayers);
-		for (cPlayerList::iterator itr = m_Players.begin(); itr != m_Players.end(); ++itr)
+		for (auto Player : m_Players)
 		{
-			cClientHandle * ch = (*itr)->GetClientHandle();
+			cClientHandle * ch = Player->GetClientHandle();
 			if (ch == nullptr)
 			{
 				continue;
 			}
 
-			ch->SendExplosion(a_BlockX, a_BlockY, a_BlockZ, static_cast<float>(a_ExplosionSize), BlocksAffected, (*itr)->GetSpeed());
+			bool InRange = (Player->GetExplosionExposureRate(ExplosionPos, static_cast<float>(a_ExplosionSize)) > 0);
+			auto Speed = InRange ? Player->GetSpeed() : Vector3d{};
+			ch->SendExplosion(a_BlockX, a_BlockY, a_BlockZ, static_cast<float>(a_ExplosionSize), BlocksAffected, Speed);
 		}
 	}