ListBox firmware using OpenGl ES scrolling

Question

I am trying to create a shared list in OpenGl ES (for iPhone / iTouch) and I ran into some riddle with clipping ListBoxItems. Each ListBoxItem object will know how to draw itself. The listbox I create will just draw one by one. But what if the number of items is greater than the ListBox? I will need to scroll (not a problem) ListBoxItems up and down. This will be a smooth scroll, so there will be times when the ListBoxItem will be half (or more or less) visible and the other part will be hidden because it is “outside” the ListBox area. How to make this crop work correctly when I create a ListBox widget?

Thanks for any help or links you have,

~ Eric

Answer 1

If you need to crop rendering, use glScissor!

void glScissor( GLint x, GLint y, GLsizei width, GLsizei height )