From ede56a5750a1880107589076a67ba68b78608427 Mon Sep 17 00:00:00 2001
From: Tiger Wang <ziwei.tiger@outlook.com>
Date: Thu, 16 Apr 2020 22:27:04 +0100
Subject: =?UTF-8?q?=E0=B2=A0=5F=E0=B2=A0=20(#4660)?=
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+ Provisional handling for observers
---
 .../IncrementalRedstoneSimulator/ObserverHandler.h | 106 +++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 src/Simulator/IncrementalRedstoneSimulator/ObserverHandler.h

(limited to 'src/Simulator/IncrementalRedstoneSimulator/ObserverHandler.h')

diff --git a/src/Simulator/IncrementalRedstoneSimulator/ObserverHandler.h b/src/Simulator/IncrementalRedstoneSimulator/ObserverHandler.h
new file mode 100644
index 000000000..cb5bc74fc
--- /dev/null
+++ b/src/Simulator/IncrementalRedstoneSimulator/ObserverHandler.h
@@ -0,0 +1,106 @@
+
+#pragma once
+
+#include "RedstoneHandler.h"
+#include "../../Blocks/BlockObserver.h"
+
+
+
+
+
+class cObserverHandler : public cRedstoneHandler
+{
+public:
+
+	inline static bool IsOn(NIBBLETYPE a_Meta)
+	{
+		return (a_Meta & 0x8) == 0x8;
+	}
+
+	static bool ShouldPowerOn(cWorld & a_World, const Vector3i a_Position, NIBBLETYPE a_Meta, cIncrementalRedstoneSimulatorChunkData * a_Data)
+	{
+		BLOCKTYPE BlockType;
+		NIBBLETYPE BlockMeta;
+		if (!a_World.GetBlockTypeMeta(a_Position + cBlockObserverHandler::GetObservingFaceOffset(a_Meta), BlockType, BlockMeta))
+		{
+			return false;
+		}
+
+		// Cache the last seen block type and meta in the power data for this position
+		auto Observed = PoweringData(BlockType, BlockMeta);
+		auto Previous = a_Data->ExchangeUpdateOncePowerData(a_Position, Observed);
+
+		// Determine if to signal an update based on the block previously observed changed
+		return (Previous.PoweringBlock != Observed.PoweringBlock) || (Previous.PowerLevel != Observed.PowerLevel);
+	}
+
+	virtual unsigned char GetPowerDeliveredToPosition(cWorld & a_World, Vector3i a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta, Vector3i a_QueryPosition, BLOCKTYPE a_QueryBlockType) const override
+	{
+		if (IsOn(a_Meta) && (a_QueryPosition == (a_Position + cBlockObserverHandler::GetSignalOutputOffset(a_Meta))))
+		{
+			return 15;
+		}
+
+		return 0;
+	}
+
+	virtual unsigned char GetPowerLevel(cWorld & a_World, Vector3i a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta) const override
+	{
+		return IsOn(a_BlockType) ? 15 : 0;
+	}
+
+	virtual cVector3iArray Update(cWorld & a_World, Vector3i a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta, PoweringData a_PoweringData) const override
+	{
+		// LOGD("Evaluating Lenny the observer (%i %i %i)", a_Position.x, a_Position.y, a_Position.z);
+
+		auto Data = static_cast<cIncrementalRedstoneSimulator *>(a_World.GetRedstoneSimulator())->GetChunkData();
+		auto DelayInfo = Data->GetMechanismDelayInfo(a_Position);
+
+		if (DelayInfo == nullptr)
+		{
+			if (!ShouldPowerOn(a_World, a_Position, a_Meta, Data))
+			{
+				return {};
+			}
+
+			// From rest, we've determined there was a block update
+			// Schedule power-on 1 tick in the future
+			Data->m_MechanismDelays[a_Position] = std::make_pair(1, true);
+
+			return {};
+		}
+
+		int DelayTicks;
+		bool ShouldPowerOn;
+		std::tie(DelayTicks, ShouldPowerOn) = *DelayInfo;
+
+		if (DelayTicks != 0)
+		{
+			return {};
+		}
+
+		if (ShouldPowerOn)
+		{
+			// Remain on for 1 tick before resetting
+			*DelayInfo = std::make_pair(1, false);
+			a_World.SetBlockMeta(a_Position.x, a_Position.y, a_Position.z, a_Meta | 0x8, a_Meta);
+		}
+		else
+		{
+			// We've reset. Erase delay data in preparation for detecting further updates
+			Data->m_MechanismDelays.erase(a_Position);
+			a_World.SetBlockMeta(a_Position.x, a_Position.y, a_Position.z, a_Meta & ~0x8, a_Meta);
+		}
+
+		return { a_Position + cBlockObserverHandler::GetSignalOutputOffset(a_Meta) };
+	}
+
+	virtual cVector3iArray GetValidSourcePositions(cWorld & a_World, Vector3i a_Position, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta) const override
+	{
+		UNUSED(a_World);
+		UNUSED(a_Position);
+		UNUSED(a_BlockType);
+		UNUSED(a_BlockType);
+		return {};
+	}
+};
-- 
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