title: How do I draw a grid of squares the size of a fraction of the screen in opengl?
body: <p>I have the whole screen ( I may make the area smaller than the window size eventually, maybe to show scores and other relevant stats? I'm probably far from that point though ).
  I want to draw a grid of squares.</p>
  
  <p>The size of these squares should be a certain fraction of the size of the screen, eg. 1/2, 1/3, 1/9, etc.</p>
  
  <p>I am passing an int that starts at 2, which will help me end up with a 2x2 grid of coloured squares. After certain conditions are met, this int will increment by 1, and I'll end up with a grid 3x3, 4x4 etc. ( You shouldn't worry about any actual 'game logic', I'll try to figure that out myself :P )</p>
  
  <p>What I'm finding confusing, is the whole -1.0 to +1.0 coordinates opengl uses ( I hope I haven't gotten this completely wrong XD) . I have basic knowledge in SDL, and so I'm used to using 0 to 'screen height/width' coordinates. However, I don't think SDL's graphics is suitable for what I want to try, so I'm attempting to use opengl with SDL.</p>
  
  <p>How might I go about figuring out the coordinates and dimensions for these squares, and actually drawing them?</p>
  
  <p>( I'm not going to post any code, because I doubt what I have so far will help, but this is inside a single function that does all drawing )</p>
  
  <p>extra : If any of you know how to turn coordinates that look like (x=32, y=128), for example, into opengl's floats, that might make life a whole lot easier for me, and I could figure out the coordinates, dimensions and drawing myself. (Yes, I know that opengl goes from -1.0 to +1.0 no matter the window size, so something like this wouldn't scale, but I'm perfectly fine with that)</p>