How To Tile In A n-sided Polygon

Hi.
I m new to opengl and was making an application in which i require to texture a polygon(n-sided) with an image…So how ca n i do it…
i know that for a 4 sided polygon i can assign the tex coord as (0,0), (0,3), (3,3), (3,0) if i want to repeat it 9 times in the polygon…But how to do it if i want to do it for say any n sided polygon…

If your n-sided polygon lie on the xy plane before transformation, use x and y coord of the vertex for it’s texture coord.