步骤 3 - 实例化预设¶
在此步骤中，您将学习如何从 Lua 脚本实例化预设。
要将预设件实例化到节点树中：
找到具有
tryAcquireResource的预设。使用
instantiate从预设创建一个节点。使用
addChild将节点添加到节点树中。
-- Find the node with the alias "Grid".
local grid = contextNode:lookupNode("#Grid")
assert(grid)
-- Find the "Piece" prefab.
local piecePrefab = contextNode:tryAcquireResource("kzb://fifteen_puzzle/Prefabs/Piece")
-- Use the piecePrefab to create a node named "New piece".
local node = piecePrefab:instantiate("New piece")
-- Add the node to the grid.
grid:addChild(node)
将拼图块添加到拼图网格中。¶
实例化 Piece 预设以按顺序从 1 到 15 填充拼图网格中的 15 个块。您将最后一个网格槽留空，以便可以进行游戏。
要将拼图块添加到拼图网格中，在 Script Editor 中，将 new_game.lua 脚本的内容替换为：
print("Entering new_game.lua")
-- Find the "Grid" node using its alias.
local grid = contextNode:lookupNode("#Grid")
assert(grid)
-- Find the "fifteen_puzzle.PieceIndex" custom property type.
local PieceIndexProperty = PropertyType:find("fifteen_puzzle.PieceIndex")
-- Find the "Piece" prefab.
local piecePrefab = contextNode:tryAcquireResource("kzb://fifteen_puzzle/Prefabs/Piece")
-- Declare the constants for the grid size and number of pieces.
-- The number of pieces is one less than the number of grid slots
-- because you need an empty slot to play the game.
local RowCount = 4
local ColumnCount = 4
local PieceCount = RowCount * ColumnCount - 1
-- Remove all grid items that were created in the project or by the earlier
-- executions of the script.
grid:removeAllChildren()
-- Create the grid child nodes.
for i = 1,PieceCount do
-- Create a grid item.
local piece = piecePrefab:instantiate("piece_" .. i)
-- Assign the number to the piece.
piece:setProperty(PieceIndexProperty, i)
-- Set the grid coordinates of the node.
-- Use integer division to get the row index and modulo to get the column index.
local row = (i-1) // ColumnCount
local column = (i-1) % ColumnCount
piece:setProperty(GridLayout2D.RowProperty, row)
piece:setProperty(GridLayout2D.ColumnProperty, column)
-- Add the node to the grid.
grid:addChild(piece)
end
print("Exiting new_game.lua")
当您保存脚本并在 Preview 中点击 
时，脚本会按顺序将网格填充为 15 个从 1 到 15 的部分，并将网格中的最后一个槽留空。
