From 4f554e91abd861323aaf9f46d75ff0350a519cef Mon Sep 17 00:00:00 2001
From: DarkoGNU <42816979+DarkoGNU@users.noreply.github.com>
Date: Thu, 21 Apr 2022 20:56:21 +0200
Subject: Implement farmland trampling (#5401)

* Add DarkoGNU to CONTRIBUTORS

* HandleFarmlandTrampling function & its docs

* Fix decimal separators (, -> .)

* Fix style. Adjust thresholds. Make function non-virtual

* Adjust thresholds again. Prepare for fixing #5402

* Trying to fix falling through farmlands

* Another style fix

* Add FarmlandTramplingEnabled to world.ini

* Docs for IsFarmlandTramplingEnabled

* Style

* Farmland trampling - handling the random chance

* Trampling kinda works, very buggy

* Trying to fix clang-tidy

* Fix trampling

* Trying to fix the 'undocumented API symbol'

* Implement bearbin's suggestions

* Calculate volume properly

* Don't use std::pow for squaring

* Improved comments

* Really, should comments' style be checked?
---
 src/Entities/Pawn.cpp | 52 +++++++++++++++++++++++++++++++++++++++++++++++++--
 src/Entities/Pawn.h   | 10 ++++++++++
 2 files changed, 60 insertions(+), 2 deletions(-)

(limited to 'src/Entities')

diff --git a/src/Entities/Pawn.cpp b/src/Entities/Pawn.cpp
index 990ea8096..cf2dd274f 100644
--- a/src/Entities/Pawn.cpp
+++ b/src/Entities/Pawn.cpp
@@ -8,6 +8,7 @@
 #include "../Bindings/PluginManager.h"
 #include "../BoundingBox.h"
 #include "../Blocks/BlockHandler.h"
+#include "../Blocks/BlockFarmland.h"
 #include "../EffectID.h"
 #include "../Mobs/Monster.h"
 
@@ -430,7 +431,9 @@ void cPawn::HandleFalling(void)
 
 	if (OnGround)
 	{
-		auto Damage = static_cast<int>(m_LastGroundHeight - GetPosY() - 3.0);
+		auto FallHeight = m_LastGroundHeight - GetPosY();
+		auto Damage = static_cast<int>(FallHeight - 3.0);
+
 		if ((Damage > 0) && !FallDamageAbsorbed)
 		{
 			if (IsElytraFlying())
@@ -438,7 +441,6 @@ void cPawn::HandleFalling(void)
 				Damage = static_cast<int>(static_cast<float>(Damage) * 0.33);
 			}
 
-			// Fall particles:
 			if (const auto Below = POS_TOINT.addedY(-1); Below.y >= 0)
 			{
 				const auto BlockBelow = GetWorld()->GetBlock(Below);
@@ -448,6 +450,7 @@ void cPawn::HandleFalling(void)
 					Damage = std::clamp(static_cast<int>(static_cast<float>(Damage) * 0.2), 1, 20);
 				}
 
+				// Fall particles
 				GetWorld()->BroadcastParticleEffect(
 					"blockdust",
 					GetPosition(),
@@ -463,6 +466,15 @@ void cPawn::HandleFalling(void)
 
 		m_bTouchGround = true;
 		m_LastGroundHeight = GetPosY();
+
+		// Farmland trampling. Mobs smaller than 0.512 cubic blocks won't trample (Java Edition's behavior)
+		// We only have width and height, so we have to calculate Width^2
+		if (GetWorld()->IsFarmlandTramplingEnabled() &&
+			(BlockAtFoot == E_BLOCK_FARMLAND) &&
+			(GetWidth() * GetWidth() * GetHeight() >= 0.512))
+		{
+			HandleFarmlandTrampling(FallHeight);
+		}
 	}
 	else
 	{
@@ -478,6 +490,42 @@ void cPawn::HandleFalling(void)
 
 
 
+void cPawn::HandleFarmlandTrampling(double a_FallHeight)
+{
+	bool ShouldTrample = true;
+	auto & Random = GetRandomProvider();
+
+	// No trampling if FallHeight <= 0.6875
+	if (a_FallHeight <= 0.6875)
+	{
+		ShouldTrample = false;
+	}
+	// For FallHeight <= 1.5625 we need to get a random bool
+	else if (a_FallHeight <= 1.0625)
+	{
+		ShouldTrample = Random.RandBool(0.25);
+	}
+	else if (a_FallHeight <= 1.5625)
+	{
+		ShouldTrample = Random.RandBool(0.66);
+	}
+	// For FallHeight > 1.5625 we always trample - ShouldTrample remains true
+
+	if (ShouldTrample)
+	{
+		auto AbsPos = GetPosition().Floor();
+		GetWorld()->DoWithChunkAt(AbsPos, [&](cChunk & Chunk)
+		{
+			cBlockFarmlandHandler::TurnToDirt(Chunk, AbsPos);
+			return true;
+		});
+	}
+}
+
+
+
+
+
 void cPawn::OnRemoveFromWorld(cWorld & a_World)
 {
 	StopEveryoneFromTargetingMe();
diff --git a/src/Entities/Pawn.h b/src/Entities/Pawn.h
index 222e8f3b8..c0801ebb3 100644
--- a/src/Entities/Pawn.h
+++ b/src/Entities/Pawn.h
@@ -33,6 +33,16 @@ public:
 	virtual void HandleFalling(void);
 	virtual void OnRemoveFromWorld(cWorld & a_World) override;
 
+	/** Handles farmland trampling when hitting the ground.
+	Algorithm:
+	fall height <= 0.6875 blocks: no trampling
+	fall height > 0.6875 and <= 1.0625: 25% chance of trampling
+	fall height > 1.0625 and <= 1.5625: 66% chance of trampling
+	fall height > 1.5625: always trample
+	The values may differ from vanilla, they were determined experimentally.
+	*/
+	void HandleFarmlandTrampling(double a_FallHeight);
+
 	/** Tells all pawns which are targeting us to stop targeting us. */
 	void StopEveryoneFromTargetingMe();
 
-- 
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