基于cocos2d-x的spine动画残影拖尾效果

在游戏研发过程中，残影拖尾效果是有一定需求的。

本例使用RenderTexture类实现残影效果，基于quick-3.3

MainScene.lua 主要是用来加载Spine动画，处理触摸拖动

local ShadowUtil = require("app.shadow.ShadowUtil")

local MainScene = class("MainScene", function()
    return display.newScene("MainScene")
end)

function MainScene:ctor()
    local layer = display.newColorLayer(cc.c4b(255, 255, 255,0))
    self:addChild(layer)

    self.calcTime = 0

    local skeletonNode = sp.SkeletonAnimation:create("spine/spineboy.json", "spine/spineboy.atlas", 0.6)
     skeletonNode:setScale(0.5)
     local windowSize = cc.Director:getInstance():getWinSize()
    skeletonNode:setPosition(cc.p(windowSize.width / 2, 20))
     skeletonNode:setAnimation(0, "walk", true)
      self:addChild(skeletonNode,1)

      local touchBeginPoint = nil
    local function onTouchBegan(touch, event)
        local location = touch:getLocation()
        print("onTouchBegan: %0.2f, %0.2f", location.x, location.y)
        touchBeginPoint = {x = location.x, y = location.y}
        return true
    end

    local function onTouchMoved(touch, event)
        local location = touch:getLocation()
        if touchBeginPoint then
            local cx, cy = skeletonNode:getPosition()
            skeletonNode:setPosition(cx + location.x - touchBeginPoint.x,
                                  cy + location.y - touchBeginPoint.y)
            touchBeginPoint = {x = location.x, y = location.y}

            self.calcTime = self.calcTime + 1
            if self.calcTime == 10 then
                self.calcTime = 0
                local shadow = ShadowUtil.new()
                shadow:addGhost(skeletonNode)
            end
        end
    end

    local function onTouchEnded(touch, event)
        local location = touch:getLocation()
        print("onTouchEnded: %0.2f, %0.2f", location.x, location.y)
        touchBeginPoint = nil
    end


      local listener = cc.EventListenerTouchOneByOne:create()
      listener:registerScriptHandler(onTouchBegan,cc.Handler.EVENT_TOUCH_BEGAN )
    listener:registerScriptHandler(onTouchMoved,cc.Handler.EVENT_TOUCH_MOVED )
    listener:registerScriptHandler(onTouchEnded,cc.Handler.EVENT_TOUCH_ENDED )

    local eventDispatcher = layer:getEventDispatcher()
    eventDispatcher:addEventListenerWithSceneGraphPriority(listener, layer)
end

function MainScene:onEnter()

end

function MainScene:onExit()

end

return MainScene

ShadowUtil.lua用来生成残影，并且加入渐隐的动作，最后移除掉残影

--
local ShadowUtil = class("ShadowUtil")

function ShadowUtil:ctor()
    -- body
end

--加残影
--node 节点
--deltime 间隔生成时间
function ShadowUtil:addGhost(node,deltime)
    local size = node:getBoundingBox()
    local posx,posy = node:getPosition()
    -- dump(size)
    print("pox:"..posx.."  posy:"..posy)
    if size.width < 1 then
        return
    end
    local canvas = cc.RenderTexture:create(size.width,size.height)
    node:setPosition(size.width/2,0)
    canvas:begin()
    node:visit()
    canvas:endToLua()
    cc.Director:getInstance():getRenderer():render()
    node:setPosition(posx,posy)

    local ghostSp = cc.Sprite:createWithTexture(canvas:getSprite():getTexture())
    ghostSp:setAnchorPoint(0.5,0)
    ghostSp:setPosition(posx, posy)
    ghostSp:setFlippedY(true);
    local fade = cc.Sequence:create(cc.FadeTo:create(1.0, 0),cc.CallFunc:create(function ()
        ghostSp:removeFromParent()
    end))
    node:getParent():addChild(ghostSp)
    ghostSp:runAction(fade)
end


return ShadowUtil

在RenderTexture生成的Sprite的上还可以用blend之类的效果实现带颜色的影子或者白色半透明的影子之类的效果

注意：需要重新导出luabinding，包括Render类，还有Director的getRender。

感谢于小钗聚聚提供思路