At long last... Piston animations!

* Fixes #3198
* Fixes #57 (again lol)

src/Blocks/BlockPiston.cpp

@@ -214,9 +214,31 @@ bool cBlockPistonHandler::CanPushBlock(
 
 void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
 {
+	{
+		// Broadcast block action first. Will do nothing if piston cannot in fact push
+
 		BLOCKTYPE pistonBlock;
 		NIBBLETYPE pistonMeta;
 		a_World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);
+		a_World.BroadcastBlockAction(a_BlockPos, PistonExtendAction, pistonMeta, pistonBlock);
+	}
+
+	// Client expects the server to "play" the animation before setting the final blocks
+	// However, we don't confuse animation with the underlying state of the world, so emulate by delaying 1 tick
+	// (Probably why vanilla has so many dupe glitches with sand and pistons lolol)
+
+	a_World.ScheduleTask(1, [a_BlockPos](cWorld & World)
+		{
+			BLOCKTYPE pistonBlock;
+			NIBBLETYPE pistonMeta;
+			World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);
+
+			if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
+			{
+				// Ensure we operate on a piston to avoid spurious behaviour
+				// Note that the scheduled task may result in the block type of a_BlockPos changing
+				return;
+			}
 
 			if (IsExtended(pistonMeta))
 			{
@@ -225,26 +247,26 @@ void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
 			}
 
 			Vector3i pushDir = MetadataToOffset(pistonMeta);
-
 			Vector3iSet blocksPushed;
-	if (!CanPushBlock(a_BlockPos + pushDir, a_World, true, blocksPushed, pushDir))
+			if (!CanPushBlock(a_BlockPos + pushDir, World, true, blocksPushed, pushDir))
 			{
 				// Can't push anything, bail out
 				return;
 			}
-
+			PushBlocks(blocksPushed, World, pushDir);
-	a_World.BroadcastBlockAction(a_BlockPos, 0, pistonMeta, pistonBlock);
-	a_World.BroadcastSoundEffect("block.piston.extend", a_BlockPos, 0.5f, 0.7f);
-
-	PushBlocks(blocksPushed, a_World, pushDir);
 
 			// Set the extension and the piston base correctly
 			Vector3i extensionPos = a_BlockPos + pushDir;
-	a_World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta | 0x8);
+			World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta | 0x8);
-	a_World.SetBlock(
+			World.SetBlock(
 				extensionPos.x, extensionPos.y, extensionPos.z,
 				E_BLOCK_PISTON_EXTENSION, pistonMeta | (IsSticky(pistonBlock) ? 8 : 0)
 			);
+
+			// Play sound effect only if extended successfully
+			World.BroadcastSoundEffect("block.piston.extend", a_BlockPos, 0.5f, 0.7f);
+		}
+	);
 }
 
 
@@ -252,10 +274,26 @@ void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
 
 
 void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
+{
 	{
 		BLOCKTYPE pistonBlock;
 		NIBBLETYPE pistonMeta;
 		a_World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);
+		a_World.BroadcastBlockAction(a_BlockPos, PistonRetractAction, pistonMeta, pistonBlock);
+	}
+
+	a_World.ScheduleTask(1, [a_BlockPos](cWorld & World)
+		{
+			BLOCKTYPE pistonBlock;
+			NIBBLETYPE pistonMeta;
+			World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);
+
+			if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
+			{
+				// Ensure we operate on a piston to avoid spurious behaviour
+				// Note that the scheduled task may result in the block type of a_BlockPos changing
+				return;
+			}
 
 			if (!IsExtended(pistonMeta))
 			{
@@ -267,18 +305,18 @@ void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
 
 			// Check the extension:
 			Vector3i extensionPos = a_BlockPos + pushDir;
-	if (a_World.GetBlock(extensionPos) != E_BLOCK_PISTON_EXTENSION)
+			if (World.GetBlock(extensionPos) != E_BLOCK_PISTON_EXTENSION)
 			{
 				LOGD("%s: Piston without an extension - still extending, or just in an invalid state?", __FUNCTION__);
 				return;
 			}
 
-	// Remove Extension
+			// Remove extension, update base state
-	a_World.SetBlock(extensionPos.x, extensionPos.y, extensionPos.z, E_BLOCK_AIR, 0);
+			World.SetBlock(extensionPos.x, extensionPos.y, extensionPos.z, E_BLOCK_AIR, 0);
+			World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta & ~(8));
 
-	a_World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta & ~(8));
+			// (Retraction is always successful, but play in the task for consistency)
-	a_World.BroadcastBlockAction(a_BlockPos, 1, pistonMeta & ~(8), pistonBlock);
+			World.BroadcastSoundEffect("block.piston.contract", a_BlockPos, 0.5f, 0.7f);
-	a_World.BroadcastSoundEffect("block.piston.contract", a_BlockPos, 0.5f, 0.7f);
 
 			if (!IsSticky(pistonBlock))
 			{
@@ -287,18 +325,20 @@ void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
 			}
 
 			// Get the block to pull
-	a_BlockPos += pushDir * 2;
+			Vector3i AdjustedPosition = a_BlockPos + pushDir * 2;
 			// Try to "push" the pulling block in the opposite direction
 			pushDir *= -1;
 
 			Vector3iSet pushedBlocks;
-	if (!CanPushBlock(a_BlockPos, a_World, false, pushedBlocks, pushDir))
+			if (!CanPushBlock(AdjustedPosition, World, false, pushedBlocks, pushDir))
 			{
 				// Not pushable, bail out
 				return;
 			}
 
-	PushBlocks(pushedBlocks, a_World, pushDir);
+			PushBlocks(pushedBlocks, World, pushDir);
+		}
+	);
 }
 
 

src/Blocks/BlockPiston.h

@@ -100,6 +100,12 @@ private:
 
 	typedef std::unordered_set<Vector3i, VectorHasher<int>> Vector3iSet;
 
+	/** Piston extension block action */
+	static const Byte PistonExtendAction = 0U;
+
+	/** Piston retraction block action */
+	static const Byte PistonRetractAction = 1U;
+
 	/** Returns true if the piston (specified by blocktype) is a sticky piston */
 	static inline bool IsSticky(BLOCKTYPE a_BlockType) { return (a_BlockType == E_BLOCK_STICKY_PISTON); }
 

src/Simulator/IncrementalRedstoneSimulator/PistonHandler.h

@@ -36,26 +36,13 @@ public:
 	virtual cVector3iArray Update(cWorld & a_World, Vector3i a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta, PoweringData a_PoweringData) const override
 	{
 		// LOGD("Evaluating pisty the piston (%d %d %d)", a_Position.x, a_Position.y, a_Position.z);
-		auto Data = static_cast<cIncrementalRedstoneSimulator *>(a_World.GetRedstoneSimulator())->GetChunkData();
-		auto DelayInfo = Data->GetMechanismDelayInfo(a_Position);
 
-		// Delay is used here to prevent an infinite loop (#3168)
-		if (DelayInfo == nullptr)
-		{
 		bool ShouldBeExtended = (a_PoweringData.PowerLevel != 0);
-			if (ShouldBeExtended != cBlockPistonHandler::IsExtended(a_Meta))
+		if (ShouldBeExtended == cBlockPistonHandler::IsExtended(a_Meta))
 		{
-				Data->m_MechanismDelays[a_Position] = std::make_pair(1, ShouldBeExtended);
+			return {};
 		}
-		}
-		else
-		{
-			int DelayTicks;
-			bool ShouldBeExtended;
-			std::tie(DelayTicks, ShouldBeExtended) = *DelayInfo;
 
-			if (DelayTicks == 0)
-			{
 		if (ShouldBeExtended)
 		{
 			cBlockPistonHandler::ExtendPiston(a_Position, a_World);
@@ -65,9 +52,8 @@ public:
 			cBlockPistonHandler::RetractPiston(a_Position, a_World);
 		}
 
-				Data->m_MechanismDelays.erase(a_Position);
+		// It is necessary to delay after a signal to prevent an infinite loop (#3168)
-			}
+		// However, that is present as a side effect of the implementation of piston animation in Blocks\BlockPiston.cpp
-		}
 
 		return {};
 	}

src/Simulator/IncrementalRedstoneSimulator/RedstoneSimulatorChunkData.h

@@ -60,7 +60,6 @@ public:
 
 	/** Structure storing position of mechanism + it's delay ticks (countdown) & if to power on */
 	std::unordered_map<Vector3i, std::pair<int, bool>, VectorHasher<int>> m_MechanismDelays;
-	std::unordered_map<Vector3i, bool, VectorHasher<int>> m_UpdateOncePositions;
 
 private: