Hmm.. worked on it for about an hour and still confused.. Why every second vertex?

I tried doubling the array size then reading it at half.. Which works very well, but it's not very efficient (about 170fps, compared to 430fps), which is very slow for a water simulation..

EDIT: It must be something to do with the arrays. Hopefully that webpage helps you to understand.. Maybe you could rewrite the 2 lines of simulation?

I used to be a c++ guy. I might turn this into a DLL if it works..

Thanks again for your help..