Random Starting Point in Slideshow?

[morykwas]

Hi, everyone--
On my website (riveroftimephotography.com) I'm using a script that I found here:

http://www.javascriptsource.com/imag...cript--ii.html

The script works great and I like it a lot. It displays the images in order from 0 to 15.
QUESTION:
How can I have a random starting point each time? Instead of always starting at zero, I want it to start somewhere in the middle. The order of slides can stay the same.
I would appreciate any help you can give me.
Many thanks,
--Ed

[holyhttp]

It appear the initial value of the variable j determines which slide is displayed first:
var j=0;
You could move that line below var p = Pic.length in order to use the variable p to generate a random number:

var p = Pic.length
var j = Math.round((p-1)*Math.random());

The starting point will then be random. That mean it might start at 0, somewhere in the middle or towards the last slide.

[morykwas]

Holyhttp, that works perfectly. Thank you so much for answering my question! --Ed

[walahh]

I want to do something exactly what morykwas is doing, but instead of starting the slideshow w/ same image every time, i want to start at random point. How can I achieve that?

For example, in morykwas's case, s/he is starting the slideshow with the welcome image (<img src="home-welcome.jpg" name='SlideShow' width="1072" height="712">) every time and then randomly picking next images from the Pic[]

on the other hand, I want to start the random slideshow directly from the Pic[]. can some one plz help me with this? Thank you!

[holyhttp]

It's just a matter of choosing a random image from your set than assigning its URL to the "src" attribute of your image tag.
Suppose your image tag is:
<img src="" id="slideshow" width="400" height="300">

var pictures,folder,timer;

function initSlideshow(){
folder='URL of images folder';
pictures=['image1.jpg', 'image2.jpg',...]; // ... for other images
var p=pictures.length;
var j=Math.random()*(p-1);
var slideshow=document.getElementById("slideshow");
swapImage(j);
}

function swapImage(j){
clearTimeout(timer);
if(j>=pictures.length) j=0;

var imgurl=folder+pictures[j];
slideshow.setAttribute("src", imgurl);]
j++;

setTimeout(function(){swapImage(j);}, 5000); //swap slide every 5000 ms or so
}