Changes

   

   

It’s just a 2D coordinate system with an inverted vertical (or y) axis. With the origin (0,0) at the top right hand corner, x increases moving right of the screen and y increases moving down. A note on depth and z is that in computers it usually increases going into the screen and decreases coming out.  The reason that the coordinate system works this way is because of the way that the back buffer prints to the front buffer (front buffer is a fancy name for screen), it starts printing from the top left corner at (0,0) then moves one pixel across the x axis to (1,0). Once a top line has been rendered to the front buffer, it will start printing at the next line and do it all over again until the entire image is drawn. This happens so fast that you can’t actually see each pixel being drawn. So when we use this call:

It’s just a 2D coordinate system with an inverted vertical (or y) axis. With the origin (0,0) at the top left hand corner, x increases moving right of the screen and y increases moving down. A note on depth and z is that in computers it usually increases going into the screen and decreases coming out.  The reason that the coordinate system works this way is because of the way that the back buffer prints to the front buffer (front buffer is a fancy name for screen), it starts printing from the top left corner at (0,0) then moves one pixel across the x axis to (1,0). Once a top line has been rendered to the front buffer, it will start printing at the next line and do it all over again until the entire image is drawn. This happens so fast that you can’t actually see each pixel being drawn. So when we use this call:

<source lang = "cpp">

<source lang = "cpp">