From 0c90ab4f6c8f0e4ddb1e674736bec5165278327d Mon Sep 17 00:00:00 2001
From: Jozef Behran <jozuejozef@gmail.com>
Date: Sun, 7 Apr 2019 12:08:27 -0500
Subject: [PATCH] Optimize random turns in dungeongen (#8129)

It turns out there is no need to return the new value and
preserve the old one in random_turn, the procedure can be
made to modify the value in-place. This saves quite a bunch
of parameter and return value copying.
---
 src/mapgen/dungeongen.cpp | 21 ++++++++++-----------
 src/mapgen/dungeongen.h   |  2 +-
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/mapgen/dungeongen.cpp b/src/mapgen/dungeongen.cpp
index 3acd22877..1aa3317cf 100644
--- a/src/mapgen/dungeongen.cpp
+++ b/src/mapgen/dungeongen.cpp
@@ -494,7 +494,7 @@ void DungeonGen::makeCorridor(v3s16 doorplace, v3s16 doordir,
 		if (partcount >= partlength) {
 			partcount = 0;
 
-			dir = random_turn(random, dir);
+			random_turn(random, dir);
 
 			partlength = random.range(1, length);
 
@@ -655,20 +655,19 @@ v3s16 turn_xz(v3s16 olddir, int t)
 }
 
 
-v3s16 random_turn(PseudoRandom &random, v3s16 olddir)
+void random_turn(PseudoRandom &random, v3s16 &dir)
 {
 	int turn = random.range(0, 2);
-	v3s16 dir;
-	if (turn == 0)
-		// Go straight
-		dir = olddir;
-	else if (turn == 1)
+	if (turn == 0) {
+		// Go straight: nothing to do
+		return;
+	} else if (turn == 1) {
 		// Turn right
-		dir = turn_xz(olddir, 0);
-	else
+		dir = turn_xz(dir, 0);
+	} else {
 		// Turn left
-		dir = turn_xz(olddir, 1);
-	return dir;
+		dir = turn_xz(dir, 1);
+	}
 }
 
 
diff --git a/src/mapgen/dungeongen.h b/src/mapgen/dungeongen.h
index 2748524c5..7d04a6254 100644
--- a/src/mapgen/dungeongen.h
+++ b/src/mapgen/dungeongen.h
@@ -34,7 +34,7 @@ class NodeDefManager;
 
 v3s16 rand_ortho_dir(PseudoRandom &random, bool diagonal_dirs);
 v3s16 turn_xz(v3s16 olddir, int t);
-v3s16 random_turn(PseudoRandom &random, v3s16 olddir);
+void random_turn(PseudoRandom &random, v3s16 &dir);
 int dir_to_facedir(v3s16 d);