tree_generation.lua

local function add_trunk_and_leaves(data, a, pos, tree_cid, leaves_cid,
		height, size, iters, is_apple_tree, apple_type)
	local x, y, z = pos.x, pos.y, pos.z
	local c_air = minetest.get_content_id("air")
	local c_ignore = minetest.get_content_id("ignore")
	local c_apple = minetest.get_content_id(apple_type)

	-- Trunk
	data[a:index(x, y, z)] = tree_cid -- Force-place lowest trunk node to replace sapling
	for yy = y + 1, y + height - 1 do
		local vi = a:index(x, yy, z)
		local node_id = data[vi]
		if node_id == c_air or node_id == c_ignore or node_id == leaves_cid then
			data[vi] = tree_cid
		end
	end

	-- Force leaves near the trunk
	for z_dist = -1, 1 do
	for y_dist = -size, 1 do
		local vi = a:index(x - 1, y + height + y_dist, z + z_dist)
		for x_dist = -1, 1 do
			if data[vi] == c_air or data[vi] == c_ignore then
				if is_apple_tree and math.random(1, 8) == 1 then
					data[vi] = c_apple
				else
					data[vi] = leaves_cid
				end
			end
			vi = vi + 1
		end
	end
	end

	-- Randomly add leaves in 2x2x2 clusters.
	for i = 1, iters do
		local clust_x = x + math.random(-size, size - 1)
		local clust_y = y + height + math.random(-size, 0)
		local clust_z = z + math.random(-size, size - 1)

		for xi = 0, 1 do
		for yi = 0, 1 do
		for zi = 0, 1 do
			local vi = a:index(clust_x + xi, clust_y + yi, clust_z + zi)
			if data[vi] == c_air or data[vi] == c_ignore then
				if is_apple_tree and math.random(1, 8) == 1 then
					data[vi] = c_apple
				else
					data[vi] = leaves_cid
				end
			end
		end
		end
		end
	end
end

function grow_giant_mushroom(pos, trunk_block, hat_block, apples_chance, apple_block)
	local apples_true = false
	if math.random() < apples_chance then
		apples_true = true
	end
	local x, y, z = pos.x, pos.y, pos.z
	local height = math.random(4, 5)
	local c_tree = minetest.get_content_id(trunk_block)
	local c_leaves = minetest.get_content_id(hat_block)

	local vm = minetest.get_voxel_manip()
	local minp, maxp = vm:read_from_map(
		{x = x - 2, y = y, z = z - 2},
		{x = x + 2, y = y + height + 1, z = z + 2}
	)
	local a = VoxelArea:new({MinEdge = minp, MaxEdge = maxp})
	local data = vm:get_data()

	add_trunk_and_leaves(data, a, pos, c_tree, c_leaves, height, 2, 8, apples_true, apple_block)

	vm:set_data(data)
	vm:write_to_map()
	vm:update_map()
end

return grow_giant_mushroom