shader图片溶解消失

--图片溶解消失：
--spr:需要溶解的图片
--speed：溶解速度
--sp2：按某个纹理溶解（可为nil，默认spr的纹理）
--finishCall：消失后回调（可为nil）
function UICommon.rongJieXiaoshi(spr,Speed,spr2,finishCall)
    local vertSource1 = [[
        attribute vec4 a_position;
        attribute vec2 a_texCoord;
        attribute vec4 a_color;
        #ifdef GL_ES
        varying lowp vec4 v_fragmentColor;
        varying mediump vec2 v_texCoord;
        #else
        varying vec4 v_fragmentColor;
        varying vec2 v_texCoord;
        #endif
         
        void main()
        {
            gl_Position = CC_PMatrix * a_position;
            v_fragmentColor = a_color;
            v_texCoord = a_texCoord;
        }
    ]]


    local fragSource1 =  [[
    #ifdef GL_ES 
        precision mediump float; 
    #endif  

    varying vec4 v_fragmentColor; 
    varying vec2 v_texCoord; 
    uniform sampler2D u_texture1;
    uniform float Threshold; 

    void main(void)
    {
        
        vec4 col=texture2D(u_texture1,v_texCoord);
        if(col.g>Threshold){
            discard;
        }
        gl_FragColor=texture2D(CC_Texture0,v_texCoord);
    }

    ]]
    if spr2 and (spr2:getDescription() == "ImageView" or spr2:getDescription() == "Button") then 
      spr2 = spr2:getVirtualRenderer():getSprite()
    end
    if spr:getDescription() == "ImageView" or spr:getDescription() == "Button" then 
      spr = spr:getVirtualRenderer():getSprite()
    end
    local Texture = spr2 and spr2:getTexture() or spr:getTexture()
    local cache = cc.GLProgramCache:getInstance()
    local pProgram = cc.GLProgram:createWithByteArrays(vertSource1,fragSource1)
    local Speed = Speed or 1
    gl.deleteShader(pProgram)
    pProgram:link()
    pProgram:updateUniforms()
    pProgram:use()
    cache:addGLProgram(glProgram, "rongJieXiaoshi")
    local glProgramState = cc.GLProgramState:getOrCreateWithGLProgram(pProgram)
    glProgramState:setUniformTexture("u_texture1",Texture);
    spr:setGLProgram(pProgram)
    spr:setGLProgramState(glProgramState)
    local Threshold = 1
    local scheduleId 
    
    _callback = function ( ... )
        glProgramState:setUniformFloat("Threshold",Threshold);
        Threshold = Threshold-0.1
        if Threshold<=0 then
            cc.Director:getInstance():getScheduler():unscheduleScriptEntry(scheduleId)
            scheduleId = nil
            if finishCall and type(finishCall) == "function" then
                finishCall()
            end
            return
        end
    end
    scheduleId = cc.Director:getInstance():getScheduler():scheduleScriptFunc(_callback, 0.1*Speed, false)
    _callback()
end