Corona SDK - 删除绘制的线组，然后再次绘制

Question

我正在尝试删除我使用小部件按钮绘制的所有线条，然后让玩家再次绘制。我曾多次尝试删除该组......并且它有效......但是当我再次绘制时它崩溃了！对这种情况有帮助吗？

display.setStatusBar( display.HiddenStatusBar )
local physics = require "physics"
physics.start()

local widget = require( "widget" )

local lines = {}
local lineGroup = display.newGroup()
local prevX,prevY
local isDrawing = false
local i = 0

local kittenCrate = display.newRect(10,10,25,25)
physics.addBody(kittenCrate, "dynamic", { density = 1, friction = 0.5, bounce = 1.6})


local function distanceBetween(x1, y1, x2, y2)
    local dist_x = x2 - x1
    local dist_y = y2 - y1
    local distanceBetween = math.sqrt((dist_x*dist_x) + (dist_y*dist_y))
    return distanceBetween
end

local function drawLine(e)
    if(e.phase == "began") then
        prevX = e.x
        prevY = e.y
        isDrawing = true
        i = i + 1
    elseif(e.phase == "moved") then
        local distance = distanceBetween(prevX, prevY, e.x, e.y)
        if(isDrawing and distance < 100) then
            if(lines[i]) then lineGroup:remove(i) end
            lines[i] = display.newLine(prevX, prevY, e.x, e.y)
            lines[i]:setColor(255, 255, 0)
            lines[i].width = 5

            local dist_x = e.x - prevX
            local dist_y = e.y - prevY
            physics.addBody(lines[i], "static", { density = 1, friction = 0.5, bounce = 1, shape = {0, 0, dist_x, dist_y, 0, 0} } )
            lineGroup:insert(lines[i])
        end
    elseif(e.phase == "ended") then
        isDrawing = false
    end
end

Runtime:addEventListener("touch",drawLine)




local function handleButtonEvent( event )

    if ( "ended" == event.phase ) then
        print( "Button was pressed and released" )

    end

end

-- Create the widget
local button1 = widget.newButton
{
    left = 100,
    top = 200,
    id = "button1",
    label = "Remove Rifts",
    onEvent = handleButtonEvent
}

Answer 1

我将您的代码更改为以下代码，它可以正常工作，但并不完美。你必须按照你的代码来看看它到底做了什么。虽然奇怪的是 Corona 在找不到您的对象时会崩溃。

display.setStatusBar( display.HiddenStatusBar )
local physics = require "physics"
physics.start()

local widget = require( "widget" )

local lines = {}
local lineGroup = display.newGroup()
local prevX,prevY
local isDrawing = false
i = 0

local kittenCrate = display.newRect(10,10,25,25)
physics.addBody(kittenCrate, "dynamic", { density = 1, friction = 0.5, bounce = 1.6})


local function distanceBetween(x1, y1, x2, y2)
    local dist_x = x2 - x1
    local dist_y = y2 - y1
    local distanceBetween = math.sqrt((dist_x*dist_x) + (dist_y*dist_y))
    return distanceBetween
end

local function drawLine(e)
    if(e.phase == "began") then
        prevX = e.x
        prevY = e.y
        isDrawing = true
        i = i + 1
        lineGroup.isVisible =true
    elseif(e.phase == "moved") then
        local distance = distanceBetween(prevX, prevY, e.x, e.y)
        if(isDrawing and distance < 100) then
            if(lines[i]) then lineGroup:remove(i) end
            lines[i] = display.newLine(prevX, prevY, e.x, e.y)
            lines[i]:setColor(255, 255, 0)
            lines[i].width = 5

            local dist_x = e.x - prevX
            local dist_y = e.y - prevY
            physics.addBody(lines[i], "static", { density = 1, friction = 0.5, bounce = 1, shape = {0, 0, dist_x, dist_y, 0, 0} } )
            lineGroup:insert(lines[i])
        end
    elseif(e.phase == "ended") then
        isDrawing = false
    end
end

Runtime:addEventListener("touch",drawLine)




local function handleButtonEvent( event )

    if ( "ended" == event.phase ) then
        print( "Button was pressed and released" )
i=0
lineGroup.isVisible = false

    end

end

-- Create the widget
local button1 = widget.newButton
{
    left = 100,
    top = 200,
    id = "button1",
    label = "Remove Rifts",
    onEvent = handleButtonEvent
}