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我正在开发像 Air Hockey 这样的游戏，我想用力击球，因为我正在使用以下代码，但这段代码的问题是，有时在用冰球击打（碰撞）木槌时，木槌会消失，有时之后puck 也从屏幕上消失了，我无法找出从屏幕上消失的对象的实际问题，但是如果我在 getVelocity 中将 local start = self.points[1] 更改为 local start = self.points[2]功能然后发生相同的消失情况，请尝试解决很长时间以来的问题我被困在这个问题中，我是Corona的新手。谢谢.....

local sqrt = math.sqrt
local physics = require("physics")
physics.start()
physics.setGravity(0,0)
physics.setDrawMode("debug")


local source
local target

-- Track velocity
local velocityTracker = {
    points = {}    
}

function velocityTracker:reset()
    self.points = {}
end

function velocityTracker:addPoint(time, x, y)   
    -- Only keep 10 points
    local count = #self.points + 1
    if count == 11 then
        count = 10
        for i=1,10 do
            -- Move older points to top
            self.points[i] = self.points[i+1]
        end 
    end
    self.points[count] = {time = time, x = x, y = y}
end

function velocityTracker:getVelocity(moves)
    if #self.points < 2 then
        return 0
    end

    local start = self.points[1]
    local totalVelocity = 0
    local now = system.getTimer()
    for i=2,#self.points do
        local finish = self.points[i]
        -- Use a vector to determine velocity
        local timePassed = finish.time - start.time
        local age = now - finish.time
        -- Only use recent points
        if age < 200 then
            local vector = {x = finish.x - start.x, y = finish.y - start.y}
            local distance = sqrt(vector.x^2 + vector.y^2)
            -- Calculate velocity
            totalVelocity = totalVelocity + (distance / timePassed)
        end
        start = finish
    end
    return totalVelocity
end

local function onPuckCollision( event )    
    if event.phase == "began" and event.other.isBall then
        -- Puck just hit a ball        
        local ball = event.other
        local puck = event.target

        -- Use a vector to determine direction of hit
        local vector = {x = ball.x - puck.x, y = ball.y - puck.y}
        -- normalize vector
        local magnitude = sqrt(vector.x^2 + vector.y^2)
        if magnitude > 0 then
            vector.x = vector.x / magnitude
            vector.y = vector.y / magnitude
        end        

        -- Use velocity to determine force
        local force = 10 * velocityTracker:getVelocity()

        local function smack()
            ball:applyForce(vector.x * force, vector.y * force, ball.x, ball.y)
        end

        -- We can't modify phyiscs in a collision handler so we
        -- `performWithDelay` to cause it to execute after this function
        timer.performWithDelay(0, smack)
    end
end

local function movePuck( event )
    local t = event.target
    local phase = event.phase
    if "began" == phase then
        local parent = t.parent
        display.getCurrentStage():setFocus( t )
        t.isFocus = true
        -- Store initial position
        t.x0 = event.x - t.x
        t.y0 = event.y - t.y
        -- Save velocity tracking state
        velocityTracker:reset()
        velocityTracker:addPoint(event.time, event.x, event.y)
    elseif t.isFocus then
        if "moved" == phase then
            t.x = event.x - t.x0
            t.y = event.y - t.y0

            -- Track a movement
            velocityTracker:addPoint(event.time, event.x, event.y)
        elseif "ended" == phase or "cancelled" == phase then
            display.getCurrentStage():setFocus( nil )
            t.isFocus = false
            velocityTracker:reset()
        end
    end
    return true
end


target = display.newCircle( 250, 250, 60 )
target.x = display.contentCenterX
target.y = display.contentCenterY
target:setFillColor(240, 200, 0)
target.isBall = true
-- Don't allow sleeping because a moving static body
-- won't always wake it if it's asleep
target.isSleepingAllowed = false 
physics.addBody(target,"dynamic",{radius = target.width / 2})


source = display.newCircle( 250, 250, 60 )
source.x = display.contentCenterX
source.y = display.contentHeight - 100
source:setFillColor( 240,125,0 )
source.isPuck = true
-- Use static body if you're going to move the object instead of
-- letting the physics engine move it
physics.addBody(source,"static", {radius = source.width / 2})

source:addEventListener("collision", onPuckCollision)

source:addEventListener("touch", movePuck)

local bounds = {
    left = -target.width,
    top = -target.height,
    right = display.contentWidth + target.width,
    bottom = display.contentHeight + target.height,
}

-- Reset ball position if it leaves screen
local function resetBall()
    if target.x < bounds.left or target.x > bounds.right or
        target.y < bounds.top or target.y > bounds.bottom
        then
        target.bodyType = 'static' -- Stop current movement
        target.x = display.contentCenterX
        target.y = display.contentCenterY                
        target.bodyType = 'dynamic' -- Make movable again

        source.x = display.contentCenterX
        source.y = display.contentHeight - 100        

        display.getCurrentStage():setFocus( nil )
    end
end

timer.performWithDelay(500, resetBall, 0)
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1 回答 1

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将 timePassed 更改为 0，您会看到这种情况总是发生，这可能就是有时会发生的情况。在除以数字之前，请务必检查数字是否不为零。

于 2013-10-03T18:42:01.063 回答