2D COORDINATE SYSTEM

• We use modeling coordinates for individual parts of a 2D scene. For example,
your polygon function put the polygon at the origin with a “radius” of 1.
Those were modeling coordinates.

• World coordinates are used for organizing the parts into a scene.

• View coordinates are the coordinates within the desired viewport which is
somewhere within the window you are using.

• Normalized coordinates are between 0 and 1 or -1 and 1 in each direction.
They are used to make the viewing process independent of the output device.

• Device coordinates are relative to the actual display area on whatever device
you are using.