Sutherland-Hodgeman Polygon Clipping Algorithm

Pseudo Code of the Algorithm

Input: Vertices of the polygon, (x_i, y_i) for i = 1, 2, ..., n representing n vertices in the polygon, and the coordinates of the opposite corners of the clipped window.

Steps of the Algorithm:

1. Initialization:

   • For each of the four boundaries of the clipped window, perform the following steps.

2. Process Each Edge:

   • For each edge e_i in the polygon, where P_i = (x_i, y_i) and P_i+1 = (x_i+1, y_i+1) represent the two vertices of edge e_i, do the following:

3. Check for Points Outside Clipping Area:

   • If both P_i and P_i+1 lie outside the clipping area, no point is written.

4. Check for Points Inside Clipping Area:

   • If both P_i and P_i+1 lie inside the clipping area, P_i is written into the points of the clipped polygon.

5. Check for One Point Inside and One Outside:

   • If P_i is inside and P_i+1 is outside, P_i is written into the points of the clipped polygon, and the intersection of e_i with the concerned boundary is calculated. The point of intersection is then written into the points of the clipped polygon.

6. Check for One Point Outside and One Inside:

   • If P_i+1 is inside and P_i is outside, P_i+1 is written into the points of the clipped polygon, and the intersection of e_i with the concerned boundary is calculated. The point of intersection is then written into the points of the clipped polygon.

This algorithm systematically processes each edge of the polygon against the boundaries of the clipped window, determining whether a vertex or an intersection point should be included in the final clipped polygon. It efficiently eliminates portions of the polygon lying outside the specified window, optimizing the rendering process in computer graphics.