改变大小后自动改变对象的物理特性答案

【问题标题】：Auto-change the physics of an object after a change of his size改变大小后自动改变对象的物理特性
【发布时间】：2013-06-05 07:45:59
【问题描述】：

我是 Corona 和 Lua 的新手。我有以下问题：

我有一个对象cake 具有这些物理参数（并不重要）：

["cake1"] = {




                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -21, 62.5  ,  -36, 62.5  ,  -50, 55.5  ,  -58.5, 46  ,  -36, -38.5  ,  57, -40.5  ,  57.5, 34  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -7.5, -63  ,  -13, -61.5  ,  -12, -64.5  ,  -8, -64.5  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -12, -64.5  ,  -13, -61.5  ,  -17.5, -56  ,  -21, -52.5  ,  -18.5, -60  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -47, -37.5  ,  -58.5, 46  ,  -58.5, -33  ,  -53, -37.5  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -26, -52.5  ,  -21, -52.5  ,  -18.5, -52  ,  -9, -47.5  ,  -6.5, -41  ,  -36, -38.5  ,  -34.5, -46  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -36, -38.5  ,  -58.5, 46  ,  -47, -37.5  ,  -42, -39.5  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -6.5, -41  ,  -9, -47.5  ,  -6.5, -44  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   25, -40.5  ,  7, -40.5  ,  17, -42.5  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   48, -42.5  ,  57, -40.5  ,  25, -40.5  ,  32, -42.5  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   -18.5, -52  ,  -21, -52.5  ,  -17.5, -56  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   7, -40.5  ,  -36, -38.5  ,  -6.5, -41  }
                    }
                     ,
                    {
                    pe_fixture_id = "", density = 2, friction = 0, bounce = 0, 
                    filter = { categoryBits = 1, maskBits = 65535, groupIndex = 0 },
                    shape = {   25, -40.5  ,  -36, -38.5  ,  7, -40.5  }
                    }



        }

当我将它插入场景时，我得到以下结果：

cake 太大，所以我用cake1:scale(0.5,0.5) 来改变他的大小。问题是物理没有自动改变以适用于它的新大小，结果是：

是否有任何简单的方法可以更改对象的大小，并且物理会自动适应新的大小，或者我必须重写它们？

【问题讨论】：

你可以在每个蛋糕上加上物理，所以当你调用每个蛋糕的大小时，物理会自动改变
@DevfaR 如果您打算使用编辑器更改对象的大小，比如说Photoshop 然后应用物理，那效率不高。我将有每个对象的 5-10 个 png 文件如果您的意思是使用 object.size 函数，我试过了，对象的大小没有改变。我真的不明白你的评论。
抱歉误会，我没有注意到最后一张看起来像是在浮动的图像，您是否尝试将半径添加到物理中，例如physics.addBody(object {radius = 0.5})

标签： lua coronasdk

【解决方案1】：

您是否为此目的使用物理编辑器..？

然后提供scaleFactor。您可以使用此比例因子为对象分配物理，如下所示：

local scaleFactor = 1.0
local physicsData = (require "shapedefs").physicsData(scaleFactor)
local shape = display.newImage("objectname.png")
physics.addBody( shape, physicsData:get("objectname") )

而且当你改变 scaleFactor 时，物理区域的大小会自动改变。

【讨论】：

【解决方案2】：

您已将比例更改为 0.5 小，这意味着您必须将所有物理对象更改为 0.5，使用计算器使您的正常数字 / 2 和小于 0 / 2 的数字将它们与结果数字相加，这里是一个例子：

24 = 12

-24 = -36

【讨论】：