How indices are distributed

#1

I am writing a glDrawElements(), for GL_QUADS. And I have 4 sweeps means 4+1=5 line paths with equal number of distributed pointed say there are 5 points in each of the line path.

So I want to know how indices will be distributed, see the set up below.

15 16 17 18 19
10 11 12 13 14
5 6 7 8 9
0 1 2 3 4

I am setting indices as ( i, i+1, i+nsweep+1, i+nsweep+2) in this order I am generating the index buffer.

But with this when I am rendering the set of Quads, I am seeting the last set is joining my origin of screen, my origin is at left-top corner of my screen.

Please advice if its the index issue or some other problem. Any suggestions highly appreciated.