Feature: Add an option to disable tree growth completely (#8415)

src/lang/english.txt

@@ -1620,9 +1620,10 @@ STR_CONFIG_SETTING_TOWN_CARGOGENMODE_BITCOUNT                   :Linear
 
 STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT                         :In game placement of trees: {STRING2}
 STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_HELPTEXT                :Control random appearance of trees during the game. This might affect industries which rely on tree growth, for example lumber mills
-STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_NONE                    :None {RED}(breaks lumber mill)
-STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_RAINFOREST              :Only in rain forests
-STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_ALL                     :Everywhere
+STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_NO_SPREAD               :Grow but don't spread {RED}(breaks lumber mill)
+STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_SPREAD_RAINFOREST       :Grow but only spread in rain forests
+STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_SPREAD_ALL              :Grow and spread everywhere
+STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_NO_GROWTH_NO_SPREAD     :Don't grow, don't spread {RED}(breaks lumber mill)
 
 STR_CONFIG_SETTING_TOOLBAR_POS                                  :Position of main toolbar: {STRING2}
 STR_CONFIG_SETTING_TOOLBAR_POS_HELPTEXT                         :Horizontal position of the main toolbar at the top of the screen

src/table/settings.ini

@@ -2391,10 +2391,10 @@ from     = SLV_132
 guiflags = SGF_MULTISTRING
 def      = 2
 min      = 0
-max      = 2
+max      = 3
 str      = STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT
 strhelp  = STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_HELPTEXT
-strval   = STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_NONE
+strval   = STR_CONFIG_SETTING_EXTRA_TREE_PLACEMENT_NO_SPREAD
 cat      = SC_BASIC
 
 [SDT_VAR]

src/tree_cmd.cpp

@@ -42,9 +42,10 @@ enum TreePlacer {
 
 /** Where to place trees while in-game? */
 enum ExtraTreePlacement {
-	ETP_NONE,       ///< Place trees on no tiles
-	ETP_RAINFOREST, ///< Place trees only on rainforest tiles
-	ETP_ALL,        ///< Place trees on all tiles
+	ETP_NO_SPREAD,           ///< Grow trees on tiles that have them but don't spread to new ones
+	ETP_SPREAD_RAINFOREST,   ///< Grow trees on tiles that have them, only spread to new ones in rainforests
+	ETP_SPREAD_ALL,          ///< Grow trees and spread them without restrictions
+	ETP_NO_GROWTH_NO_SPREAD, ///< Don't grow trees and don't spread them at all
 };
 
 /** Determines when to consider building more trees. */
@@ -635,8 +636,8 @@ static void TileLoopTreesAlps(TileIndex tile)
 static bool CanPlantExtraTrees(TileIndex tile)
 {
 	return ((_settings_game.game_creation.landscape == LT_TROPIC && GetTropicZone(tile) == TROPICZONE_RAINFOREST) ?
-		_settings_game.construction.extra_tree_placement != ETP_NONE :
-		_settings_game.construction.extra_tree_placement == ETP_ALL);
+		(_settings_game.construction.extra_tree_placement == ETP_SPREAD_ALL || _settings_game.construction.extra_tree_placement == ETP_SPREAD_RAINFOREST) :
+		_settings_game.construction.extra_tree_placement == ETP_SPREAD_ALL);
 }
 
 static void TileLoop_Trees(TileIndex tile)
@@ -662,6 +663,9 @@ static void TileLoop_Trees(TileIndex tile)
 			MarkTileDirtyByTile(tile);
 		}
 	}
+
+	if (_settings_game.construction.extra_tree_placement == ETP_NO_GROWTH_NO_SPREAD) return;
+
 	if (GetTreeCounter(tile) < 15) {
 		AddTreeCounter(tile, 1);
 		return;
@@ -755,8 +759,8 @@ static void TileLoop_Trees(TileIndex tile)
 
 void OnTick_Trees()
 {
-	/* Don't place trees if that's not allowed */
-	if (_settings_game.construction.extra_tree_placement == ETP_NONE) return;
+	/* Don't spread trees if that's not allowed */
+	if (_settings_game.construction.extra_tree_placement == ETP_NO_SPREAD || _settings_game.construction.extra_tree_placement == ETP_NO_GROWTH_NO_SPREAD) return;
 
 	uint32 r;
 	TileIndex tile;
@@ -771,7 +775,7 @@ void OnTick_Trees()
 	}
 
 	/* byte underflow */
-	if (--_trees_tick_ctr != 0 || _settings_game.construction.extra_tree_placement != ETP_ALL) return;
+	if (--_trees_tick_ctr != 0 || _settings_game.construction.extra_tree_placement == ETP_SPREAD_RAINFOREST) return;
 
 	/* place a tree at a random spot */
 	r = Random();