Fix #9241: Grove and forest tree brushes also create rainforests

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;
 }
 

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: