var cur=1;  //initial values
var dir=""; //initial values
var max=1;  //initial values

function initGallery(Prod,imgMax){
	dir = Prod + "/";
	max = imgMax;
}


function swap(imgNum) {

    document['MainImg'].src = dir + imgNum + ".jpg";
    cur= imgNum;

}

function next(){
    
    if(cur < max){
    cur = cur + 1;
    document['MainImg'].src = dir + cur + ".jpg";
    }else{
    cur = 1;
    document['MainImg'].src = dir + cur + ".jpg";
    }
}

function back(){
    
    if(cur == 1){
    cur = max;
    document['MainImg'].src = dir + cur + ".jpg";
    }else{
    cur = cur - 1;
    document['MainImg'].src = dir + cur + ".jpg";
    }
}