使用 corona sdk，旋转相同 display object 类的两个实例。

2013-2-9 19:36:47
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我已经创建了一个叫moonclass.lua的lua文件，它创建了一个月亮的显示对象。我创建了这个类的两个实例，也就是两个月亮，它们在level1.lua中创建。然而，当我试图旋转两个月亮时，只有最后一个被创建的月亮会旋转，无论我将旋转引用到哪一个月亮上。moonclasss.lua如下：

```local moon = {}

local moon_mt = { __index = moon } -- metatable local sprite

function moon.new(name) -- constructor

local newMoon = { name = name or "unnamed",

} return setmetatable( newMoon, moon_mt) end

function moon:draw(x,y,group)

sprite = display.newImage("image/moon.png") sprite.x = x sprite.y = y physics.addBody( sprite, "dynamic", { density=1, friction=0.8, bounce=0.05, radius=145 } ) group:insert (sprite) end

function moon:talk() print( self.name .. " is called." )end

function moon:y(y) sprite.y = sprite.y + y return y end

function moon:x(x) sprite.x = sprite.x + x return x end

function moon:rotate(r) sprite.rotation = sprite.rotation + r return sprite end

return moon```

和level1.lua：

```local storyboard = require ("storyboard") local scene = storyboard.newScene() storyboard.purgeScene ("menu") display.setStatusBar( display.HiddenStatusBar )

local physics = require("physics") physics.start() physics.setGravity(0, 0)

function scene:createScene(event)

local group = self.view local background = display.newGroup() local foreground = display.newGroup() group:insert(background) group:insert(foreground)

--BACKGROUND backgroundimage = display.newImage("image/galaxy background.png") foreground:insert(backgroundimage) backgroundimage.x = display.contentWidth/2 backgroundimage.y = display.contentWidth/-1 require "starclass" require "controls"

local moon = require ("moonclass") local moon1 = moon.new("moon1") moon1:draw(0,400,foreground)

local moon2 = moon.new("moon2") moon2:draw(300,400,foreground)

moon1:talk() moon2:talk()

local platform = require "platformclass" platform.draw(512,200,foreground) local platform2 = require "platformclass" platform2.draw(50,0,foreground)

local rocket = require "rocketclass" rocket.draw(200,600,foreground)

function gameloop(event)

moon2:rotate(1) moon1:rotate(-2)

end

Runtime:addEventListener("enterFrame", gameloop)

end

-- ENTER SCENE -- function scene:enterScene (event)

end -- EXIT SCENE -- function scene.exitScene(event) Runtime:removeEventListener("enterFrame", gameloop) end

scene:addEventListener("createScene", scene) scene:addEventListener("enterScene", scene) scene:addEventListener("exitScene", scene)

return scene```

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用户1847592
用户1847592 
local moon = require("moonclass")
local moon2 = require ("moonclass")

这些代码行返回同一个对象。

require 不会重复加载一个模块。

第二个 require 只是简单地返回第一个 require 返回的值。

你必须定义一个构造函数并调用它来创建新的对象。

EDIT :

local moon = {}

local moon_mt = { __index = moon }  -- metatable

function moon.new(name)   -- 构造函数
  local newMoon = {
    name = name or "未命名"
  }
  return setmetatable( newMoon, moon_mt)
end

function moon:draw(x,y,group)
  self.sprite = display.newImage("image/moon.png")
  self.sprite.x = x
  self.sprite.y = y
  physics.addBody( self.sprite, "dynamic", { density=1, friction=0.8, bounce=0.05, radius=145 } )
  group:insert (self.sprite)
end

function moon:talk()    print( self.name .. " 被称呼了。" )end

function moon:y(y)
  self.sprite.y = self.sprite.y + y
  return y
end

function moon:x(x)
  self.sprite.x = self.sprite.x + x
  return x
end

function moon:rotate(r)
  self.sprite.rotation = self.sprite.rotation + r
  return self.sprite
end

return moon
2013-02-09 13:56:41

作者:

用户1826259

用户1826259
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