The principles behind this simple 2d sprite based clipping are the same when it comes to clipping polygons. You are still trying to fit an object into a screen size. I am going to cover 2 methods I have used to clip polygons, both of them clip the 2d polygon. This means if you are using it in a 3d based environment you must convert the polygon x,y,z coordinates into screen x,y coordinates before you can use these methods. I also assume that you use an edge scanning polygon technique to draw your polygons.
Edge scanning polygon draw routines use a method of tracing down each edge of a polygon.
The X coordinate of the line is stored in a table at the corresponding Y coordinate. For more information about Edge scanning polygon draw routines please refer to the works of Chris Egerter in his tutorials 1,2 and 3. Clipping the top and bottom. Clipping the top and bottom of a polygon is done in the line draw routine. Before you start to draw your line you check to see if the Y start coordinate of the line is less than 0.