Pine trees: Add small pine tree and mix into coniferous forests

Use noises to create a varying mix in coniferous forest biomes:
Areas of large pines only, areas of small pines only, mixed areas.
While also having areas of high and low tree densities.
Saplings grow into large or small pines with equal chance.

mods/default/mapgen.lua

@@ -1758,7 +1758,7 @@ function default.register_decorations()
 	minetest.register_decoration({
 		deco_type = "schematic",
 		place_on = {"default:dirt_with_rainforest_litter", "default:dirt"},
-		sidelen = 16,
+		sidelen = 80,
 		fill_ratio = 0.1,
 		biomes = {"rainforest", "rainforest_swamp"},
 		y_max = 31000,
@@ -1771,7 +1771,7 @@ function default.register_decorations()
 	minetest.register_decoration({
 		deco_type = "schematic",
 		place_on = {"default:dirt_with_rainforest_litter", "default:dirt"},
-		sidelen = 16,
+		sidelen = 80,
 		fill_ratio = 0.005,
 		biomes = {"rainforest", "rainforest_swamp"},
 		y_max = 31000,
@@ -1781,15 +1781,15 @@ function default.register_decorations()
 		rotation = "random",
 	})
 
-	-- Taiga and temperate coniferous forest pine tree and log
+	-- Taiga and temperate coniferous forest pine tree, small pine tree and log
 
 	minetest.register_decoration({
 		deco_type = "schematic",
 		place_on = {"default:dirt_with_snow", "default:dirt_with_coniferous_litter"},
 		sidelen = 16,
 		noise_params = {
-			offset = 0.036,
-			scale = 0.022,
+			offset = 0.010,
+			scale = 0.048,
 			spread = {x = 250, y = 250, z = 250},
 			seed = 2,
 			octaves = 3,
@@ -1805,10 +1805,10 @@ function default.register_decorations()
 	minetest.register_decoration({
 		deco_type = "schematic",
 		place_on = {"default:dirt_with_snow", "default:dirt_with_coniferous_litter"},
-		sidelen = 80,
+		sidelen = 16,
 		noise_params = {
-			offset = 0.0018,
-			scale = 0.0011,
+			offset = 0.010,
+			scale = -0.048,
 			spread = {x = 250, y = 250, z = 250},
 			seed = 2,
 			octaves = 3,
@@ -1816,6 +1816,18 @@ function default.register_decorations()
 		},
 		biomes = {"taiga", "coniferous_forest", "floatland_coniferous_forest"},
 		y_max = 31000,
+		y_min = 2,
+		schematic = minetest.get_modpath("default") .. "/schematics/small_pine_tree.mts",
+		flags = "place_center_x, place_center_z",
+	})
+
+	minetest.register_decoration({
+		deco_type = "schematic",
+		place_on = {"default:dirt_with_snow", "default:dirt_with_coniferous_litter"},
+		sidelen = 80,
+		fill_ratio = 0.0018,
+		biomes = {"taiga", "coniferous_forest", "floatland_coniferous_forest"},
+		y_max = 31000,
 		y_min = 1,
 		schematic = minetest.get_modpath("default") .. "/schematics/pine_log.mts",
 		flags = "place_center_x",
@@ -2039,7 +2051,7 @@ function default.register_decorations()
 	minetest.register_decoration({
 		deco_type = "simple",
 		place_on = {"default:dirt_with_rainforest_litter"},
-		sidelen = 16,
+		sidelen = 80,
 		fill_ratio = 0.1,
 		biomes = {"rainforest"},
 		y_max = 31000,

mods/default/trees.lua

@@ -411,8 +411,14 @@ end
 -- New pine tree
 
 function default.grow_new_pine_tree(pos)
-	local path = minetest.get_modpath("default") ..
+	local path
+	if math.random() > 0.5 then
+		path = minetest.get_modpath("default") ..
 			"/schematics/pine_tree_from_sapling.mts"
+	else
+		path = minetest.get_modpath("default") ..
+			"/schematics/small_pine_tree_from_sapling.mts"
+	end
 	minetest.place_schematic({x = pos.x - 2, y = pos.y - 1, z = pos.z - 2},
 		path, "0", nil, false)
 end
@@ -421,8 +427,14 @@ end
 -- New snowy pine tree
 
 function default.grow_new_snowy_pine_tree(pos)
-	local path = minetest.get_modpath("default") ..
+	local path
+	if math.random() > 0.5 then
+		path = minetest.get_modpath("default") ..
 			"/schematics/snowy_pine_tree_from_sapling.mts"
+	else
+		path = minetest.get_modpath("default") ..
+			"/schematics/snowy_small_pine_tree_from_sapling.mts"
+	end
 	minetest.place_schematic({x = pos.x - 2, y = pos.y - 1, z = pos.z - 2},
 		path, "random", nil, false)
 end