5 files changed, 34 insertions, 9 deletions

diff --git a/src/BlockEntities/DispenserEntity.cpp b/src/BlockEntities/DispenserEntity.cpp
index e03644a0f..d6fbafadf 100644
--- a/src/BlockEntities/DispenserEntity.cpp
+++ b/src/BlockEntities/DispenserEntity.cpp
@@ -283,7 +283,7 @@ UInt32 cDispenserEntity::SpawnProjectileFromDispenser(int a_BlockX, int a_BlockY
 
 Vector3d cDispenserEntity::GetShootVector(NIBBLETYPE a_Meta)
 {
-	switch (a_Meta & 0x7)
+	switch (a_Meta & E_META_DROPSPENSER_FACING_MASK)
 	{
 		case E_META_DROPSPENSER_FACING_YP: return Vector3d( 0,  1,  0);
 		case E_META_DROPSPENSER_FACING_YM: return Vector3d( 0, -1,  0);
diff --git a/src/BlockEntities/DropSpenserEntity.cpp b/src/BlockEntities/DropSpenserEntity.cpp
index 8dddf85de..3a43e1073 100644
--- a/src/BlockEntities/DropSpenserEntity.cpp
+++ b/src/BlockEntities/DropSpenserEntity.cpp
@@ -41,7 +41,7 @@ cDropSpenserEntity::~cDropSpenserEntity()
 
 void cDropSpenserEntity::AddDropSpenserDir(int & a_BlockX, int & a_BlockY, int & a_BlockZ, NIBBLETYPE a_Direction)
 {
-	switch (a_Direction & 0x07)  // Vanilla uses the 8th bit to determine power state - we don't
+	switch (a_Direction & E_META_DROPSPENSER_FACING_MASK)
 	{
 		case E_META_DROPSPENSER_FACING_YM: a_BlockY--; return;
 		case E_META_DROPSPENSER_FACING_YP: a_BlockY++; return;
@@ -87,7 +87,7 @@ void cDropSpenserEntity::DropSpense(cChunk & a_Chunk)
 	// Broadcast a smoke and click effects:
 	NIBBLETYPE Meta = a_Chunk.GetMeta(m_RelX, m_PosY, m_RelZ);
 	int SmokeDir = 0;
-	switch (Meta)
+	switch (Meta & E_META_DROPSPENSER_FACING_MASK)
 	{
 		case E_META_DROPSPENSER_FACING_YP: SmokeDir = static_cast<int>(SmokeDirection::CENTRE); break;  // YP & YM don't have associated smoke dirs, just do 4 (centre of block)
 		case E_META_DROPSPENSER_FACING_YM: SmokeDir = static_cast<int>(SmokeDirection::CENTRE); break;
@@ -176,7 +176,7 @@ void cDropSpenserEntity::DropFromSlot(cChunk & a_Chunk, int a_SlotNum)
 
 	const int PickupSpeed = m_World->GetTickRandomNumber(4) + 2;  // At least 2, at most 6
 	int PickupSpeedX = 0, PickupSpeedY = 0, PickupSpeedZ = 0;
-	switch (Meta)
+	switch (Meta & E_META_DROPSPENSER_FACING_MASK)
 	{
 		case E_META_DROPSPENSER_FACING_YP: PickupSpeedY =  PickupSpeed; break;
 		case E_META_DROPSPENSER_FACING_YM: PickupSpeedY = -PickupSpeed; break;
diff --git a/src/BlockID.h b/src/BlockID.h
index b32b673c6..5af0cc4f5 100644
--- a/src/BlockID.h
+++ b/src/BlockID.h
@@ -536,6 +536,8 @@ enum
 	E_META_DROPSPENSER_FACING_ZP = 3,
 	E_META_DROPSPENSER_FACING_XM = 4,
 	E_META_DROPSPENSER_FACING_XP = 5,
+	E_META_DROPSPENSER_FACING_MASK = 7,
+	E_META_DROPSPENSER_ACTIVATED = 8,
 
 	// E_BLOCK_DOUBLE_STONE_SLAB metas:
 	E_META_DOUBLE_STONE_SLAB_STONE            = 0,
diff --git a/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h b/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h
index b67b8d4fb..3c9952582 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/DropSpenserHandler.h
@@ -18,6 +18,22 @@ public:
 	{
 	}
 
+	inline static bool IsActivated(NIBBLETYPE a_Meta)
+	{
+		return (a_Meta & E_META_DROPSPENSER_ACTIVATED) != 0;
+	}
+	inline static NIBBLETYPE SetActivationState(NIBBLETYPE a_Meta, bool IsOn)
+	{
+		if (IsOn)
+		{
+			return a_Meta | E_META_DROPSPENSER_ACTIVATED;  // set the bit
+		}
+		else
+		{
+			return a_Meta & ~E_META_DROPSPENSER_ACTIVATED;  // clear the bit
+		}
+	}
+
 	virtual unsigned char GetPowerDeliveredToPosition(const Vector3i & a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta, const Vector3i & a_QueryPosition, BLOCKTYPE a_QueryBlockType) override
 	{
 		UNUSED(a_Position);
@@ -39,8 +55,9 @@ public:
 	virtual cVector3iArray Update(const Vector3i & a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta, PoweringData a_PoweringData) override
 	{
 		// LOGD("Evaluating spencer the dropspenser (%d %d %d)", a_Position.x, a_Position.y, a_Position.z);
-
-		if (a_PoweringData.PowerLevel > 0)
+		bool IsPoweredNow = (a_PoweringData.PowerLevel > 0);
+		bool WasPoweredPreviously = IsActivated(a_Meta);
+		if (IsPoweredNow && !WasPoweredPreviously)
 		{
 			class cSetPowerToDropSpenser :
 				public cDropSpenserCallback
@@ -56,6 +73,12 @@ public:
 			m_World.DoWithDropSpenserAt(a_Position.x, a_Position.y, a_Position.z, DrSpSP);
 		}
 
+		// Update the internal dropspenser state if necessary
+		if (IsPoweredNow != WasPoweredPreviously)
+		{
+			m_World.SetBlockMeta(a_Position, SetActivationState(a_Meta, IsPoweredNow));
+		}
+
 		return {};
 	}
 
diff --git a/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp b/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp
index 9f8c0f39d..c7be24dc4 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp
+++ b/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp
@@ -196,12 +196,12 @@ void cIncrementalRedstoneSimulator::Simulate(float a_dt)
 		cRedstoneHandler::PoweringData Power;
 		for (const auto & Location : CurrentHandler->GetValidSourcePositions(CurrentLocation, CurrentBlock, CurrentMeta))
 		{
-			BLOCKTYPE PotentialBlock;
-			NIBBLETYPE PotentialMeta;
-			if ((Location.y < 0) || (Location.y > cChunkDef::Height))
+			if (!cChunk::IsValidHeight(Location.y))
 			{
 				continue;
 			}
+			BLOCKTYPE PotentialBlock;
+			NIBBLETYPE PotentialMeta;
 			m_World.GetBlockTypeMeta(Location.x, Location.y, Location.z, PotentialBlock, PotentialMeta);
 
 			auto PotentialSourceHandler = cIncrementalRedstoneSimulator::CreateComponent(m_World, PotentialBlock, &m_Data);