From cd8a37d2dadbea94800998c3eee43f279ebe2f77 Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <dktapps@pmmp.io>
Date: Mon, 27 Jan 2025 22:54:10 +0000
Subject: [PATCH] Skip overlapping AABB checks if the block is a cube

---
 src/world/World.php | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/src/world/World.php b/src/world/World.php
index 7bfed3c272..12cabfe0f0 100644
--- a/src/world/World.php
+++ b/src/world/World.php
@@ -1575,26 +1575,30 @@ private function getBlockCollisionBoxesForCell(int $x, int $y, int $z, array $co
 			?->getBlockStateId($x & Chunk::COORD_MASK, $y, $z & Chunk::COORD_MASK) ?? Block::EMPTY_STATE_ID;
 
 		$cellBB = null;
-		$boxes = match($collisionInfo[$stateId]){
+		$stateCollisionInfo = $collisionInfo[$stateId] ?? throw new AssumptionFailedError("This should always exist");
+		$boxes = match($stateCollisionInfo){
 			RuntimeBlockStateRegistry::COLLISION_NONE => [],
 			RuntimeBlockStateRegistry::COLLISION_CUBE => [$cellBB = AxisAlignedBB::one()->offset($x, $y, $z)],
 			default => $this->getBlockAt($x, $y, $z)->getCollisionBoxes()
 		};
 
-		foreach(Facing::OFFSET as [$dx, $dy, $dz]){
-			$offsetY = $y + $dy;
-			if($offsetY < $this->minY || $offsetY > $this->maxY){
-				continue;
-			}
-			$stateId = $this
-				->getChunk(($x + $dx) >> Chunk::COORD_BIT_SIZE, ($z + $dz) >> Chunk::COORD_BIT_SIZE)
-				?->getBlockStateId(($x + $dx) & Chunk::COORD_MASK, $offsetY, ($z + $dz) & Chunk::COORD_MASK) ?? Block::EMPTY_STATE_ID;
-			if($collisionInfo[$stateId] === RuntimeBlockStateRegistry::COLLISION_MAY_OVERFLOW){
-				$cellBB ??= AxisAlignedBB::one()->offset($x, $y, $z);
-				$extraBoxes = $this->getBlockAt($x + $dx, $offsetY, $z + $dz)->getCollisionBoxes();
-				foreach($extraBoxes as $extraBox){
-					if($extraBox->intersectsWith($cellBB)){
-						$boxes[] = $extraBox;
+		//overlapping AABBs can't make any difference if this is a cube, so we can save some CPU cycles in this common case
+		if($stateCollisionInfo !== RuntimeBlockStateRegistry::COLLISION_CUBE){
+			foreach(Facing::OFFSET as [$dx, $dy, $dz]){
+				$offsetY = $y + $dy;
+				if($offsetY < $this->minY || $offsetY > $this->maxY){
+					continue;
+				}
+				$stateId = $this
+					->getChunk(($x + $dx) >> Chunk::COORD_BIT_SIZE, ($z + $dz) >> Chunk::COORD_BIT_SIZE)
+					?->getBlockStateId(($x + $dx) & Chunk::COORD_MASK, $offsetY, ($z + $dz) & Chunk::COORD_MASK) ?? Block::EMPTY_STATE_ID;
+				if($collisionInfo[$stateId] === RuntimeBlockStateRegistry::COLLISION_MAY_OVERFLOW){
+					$cellBB ??= AxisAlignedBB::one()->offset($x, $y, $z);
+					$extraBoxes = $this->getBlockAt($x + $dx, $offsetY, $z + $dz)->getCollisionBoxes();
+					foreach($extraBoxes as $extraBox){
+						if($extraBox->intersectsWith($cellBB)){
+							$boxes[] = $extraBox;
+						}
 					}
 				}
 			}