Corona SDK：如何在屏幕的顶部和底部创建不可触摸的区域？

Question

如果我触及最顶部（比如，y=5），物体应该停止到达 y=50
如果我触摸底部（比方说y=300），物体应该停止到达 y=250

这是我到目前为止所做的：

local function movePlayer(event)
    if(event.phase == "ended") then
        transition.to(player, {y=event.y, time=3000})
    end
 end

我该怎么做？

Answer 1

这很容易通过简单的比较逻辑解决，添加此函数并将其与您喜欢的参数（例如玩家 x 和 y）一起使用，在您应用到玩家之前限制它们的值。

This function accepts three arguments - number value, low limit and high limit. And it returns a number, which is guranteed to be within these boundaries.

这是函数

function math.clamp(value, low, high)  
    if low and value <= low then
        return low
    elseif high and value >= high then
        return high
    end
    return value
end

使用示例

local actualSpeed = math.clamp(calculatedSpeed, 0, 200)

local temperature = math.clamp(temperature, -270)

player.x = math.clamp(player.x, 0, map.width)

cannon.rotation = math.clamp(cannon.rotation, -90, 90)

local age = math.clamp(age, 1, 120)

-- Six has higher probability than any other number
local luckyDice = math.clamp(math.random(1, 10), nil, 6)

source for further reading

编辑：

local backGround = display.newRect(display.actualContentWidth/2,display.actualContentHeight/2,display.actualContentWidth,display.actualContentHeight)
backGround:setFillColor( 0.5, 0.5, 0.5, 1.0 )


local player = display.newCircle(100,100,50)

function math.clamp(value, low, high)  
    if low and value <= low then
        return low
    elseif high and value >= high then
        return high
    end
    return value
end 


function movePlayer(event)
    if(event.phase == "moved") then
        local xPosition = event.x
        local yPosition = event.y

        xPosition =  math.clamp(xPosition, 0, 150)
        yPosition =  math.clamp(yPosition, 0, 150)

        transition.to(player, {x=xPosition,y=yPosition,time = 30})

    end
 end


player.touch = movePlayer

player:addEventListener( "touch", movePlayer )
backGround:addEventListener( "touch", movePlayer )

Corona SDK：如何在屏幕的顶部和底部创建不可触摸的区域？

Corona SDK: How to create untouchable area at very the top and bottom of the screen?

mobile

sdk

lua

coronasdk