Cocos2d实现刮刮卡效果

local TestScene = class("TestScene", function() return display.newScene("TestScene") end) function TestScene:ctor() end function TestScene:onEnter() self:initUI() end function TestScene:initUI() --刮刮卡底层容器 local scratchLayer = display.newLayer() scratchLayer:setContentSize(self:getBoundingBox()) self:addChild(scratchLayer) scratchLayer:setTouchEnabled(true) scratchLayer:setTouchMode(cc.TOUCH_MODE_ONE_BY_ONE) --创建RenderTexture local scratch = cc.RenderTexture:create(scratchLayer:getBoundingBox().width,scratchLayer:getBoundingBox().height) scratch:setPosition(scratchLayer:getBoundingBox().width/2,scratchLayer:getBoundingBox().height/2) scratch:retain() --需要被挂掉的精灵 本文以纯白背景代替 local bg = cc.Sprite:createWithTexture(nil, cc.rect(0,0 , scratchLayer:getBoundingBox().width,scratchLayer:getBoundingBox().height)) bg:setColor(cc.c3b(255,255,255)) bg:setPosition(scratchLayer:getBoundingBox().width/2,scratchLayer:getBoundingBox().height/2) --渲染 scratch:begin() bg:visit() scratch:endToLua() scratchLayer:addChild(scratch) --利用DrawNode创建模拟的刮除媒介 local eraser = cc.DrawNode:create() --刮除媒介是个圆 半径为20 具体可自行定义 local r = 20 eraser:drawSolidCircle(cc.p(0,0), r, 0, r, 1, 1, cc.c4f(0,0,0,0) ) eraser:retain() --开始添加触摸事件 scratchLayer:addNodeEventListener(cc.NODE_TOUCH_EVENT, function (event) --首先把点击区域刮除 eraser:setPosition(event.x,event.y) eraser:setBlendFunc(gl.ONE,gl.ZERO) scratch:begin() eraser:visit() --[[ 重点：因为点击事件回调次数限制，如果没有下面处理， 当我们快速在屏幕上滑动的时候调用次数不够，会产生一个一个刮除点 而中间并没有刮除。 以下代码为刮除两次移动中间矩形区域 ]] local isEnded = false if event.name ~= "began" then if eraser.lastPos then --矩形宽高 local width = self:getP2PDis(event, eraser.lastPos) local height = 2*r --矩形中点 local midPos = cc.p((event.x+eraser.lastPos.x)/2,(event.y+eraser.lastPos.y)/2) --旋转角度 local rotate = self:getP2PAngle(eraser.lastPos, event) --矩形刮除媒介 local polygonEraser = cc.DrawNode:create() local points = { cc.p(-width/2,-height/2), cc.p(-width/2,height/2), cc.p(width/2,height/2), cc.p(width/2,-height/2) } polygonEraser:drawPolygon(points, { fillColor = cc.c4f(0, 0, 0, 0), borderWidth = 1, borderColor = cc.c4f(0, 0, 0, 0), }) --刮除矩形区域 polygonEraser:setRotation(-rotate) polygonEraser:setPosition(midPos) polygonEraser:setBlendFunc(gl.ONE,gl.ZERO) polygonEraser:visit() scratch:endToLua() isEnded = true end end if not isEnded then scratch:endToLua() end eraser.lastPos = cc.p(event.x,event.y) if event.name == "ended" then eraser.lastPos = nil end return true end) end --两点间距 function TestScene:getP2PDis(p1,p2) local x = p1.x - p2.x local y = p1.y - p2.y return math.abs(math.sqrt(math.pow(x,2)+math.pow(y,2))) end --两点连接线倾斜角度 function TestScene:getP2PAngle(p1,p2) local x = p1.x - p2.x local y = p1.y - p2.y return 180 * (math.atan2(y, x) / math.pi) end return TestScene