From 710b758b81f69a6f6771d7e8741db819831731e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADt=20=C5=A0efl?= <vituscze@gmail.com>
Date: Sun, 12 Sep 2021 08:42:24 +0200
Subject: [PATCH] Fix #9241: Grove and forest tree brushes also create
 rainforests (#9542)

---
 src/tree_cmd.cpp | 9 ++++++++-
 src/tree_gui.cpp | 5 +++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/tree_cmd.cpp b/src/tree_cmd.cpp
index e2460f3b08..237b34fffb 100644
--- a/src/tree_cmd.cpp
+++ b/src/tree_cmd.cpp
@@ -301,9 +301,10 @@ void PlaceTreesRandomly()
  * @param treetype  Type of trees to place. Must be a valid tree type for the climate.
  * @param radius    Maximum distance (on each axis) from tile to place trees.
  * @param count     Maximum number of trees to place.
+ * @param set_zone  Whether to create a rainforest zone when placing rainforest trees.
  * @return Number of trees actually placed.
  */
-uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, uint count)
+uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, uint count, bool set_zone)
 {
 	assert(treetype < TREE_TOYLAND + TREE_COUNT_TOYLAND);
 	const bool allow_desert = treetype == TREE_CACTUS;
@@ -334,6 +335,12 @@ uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, ui
 		}
 	}
 
+	if (set_zone && IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS)) {
+		for (TileIndex t : TileArea(tile).Expand(radius)) {
+			if (GetTileType(t) != MP_VOID && DistanceSquare(tile, t) < radius * radius) SetTropicZone(t, TROPICZONE_RAINFOREST);
+		}
+	}
+
 	return planted;
 }
 
diff --git a/src/tree_gui.cpp b/src/tree_gui.cpp
index 3dab92a201..ccec4705dc 100644
--- a/src/tree_gui.cpp
+++ b/src/tree_gui.cpp
@@ -29,7 +29,7 @@
 #include "safeguards.h"
 
 void PlaceTreesRandomly();
-uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, uint count);
+uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, uint count, bool set_zone);
 
 /** Tree Sprites with their palettes */
 const PalSpriteID tree_sprites[] = {
@@ -133,7 +133,8 @@ class BuildTreesWindow : public Window
 		}
 		const uint radius = this->mode == PM_FOREST_LG ? 12 : 5;
 		const uint count = this->mode == PM_FOREST_LG ? 12 : 5;
-		PlaceTreeGroupAroundTile(tile, treetype, radius, count);
+		// Create tropic zones only when the tree type is selected by the user and not picked randomly.
+		PlaceTreeGroupAroundTile(tile, treetype, radius, count, this->tree_to_plant != TREE_INVALID);
 	}
 
 public: