Algorithm
1. Compute region codes for endpoints.
2. Check for trivial accept or reject.
3. If step 2 > no then compute midpoint of line segment
xm = (x1 + x2) / 2 ym = (y1 + y2) / 2
4. Redo step 1 > 3 for each 1/2 of line.
Example 11) P1 > 1000 2) no 3) Compute Pm P2 > 0000 for Pm > P2 1) Pm > 0000 , P2 > 0000 2) yes accept & display 

Example 2for P1 > Pm 1) P1 > 1000; Pm > 0000 2) no 3) Compute new midpoint P Do step 1, 2 for P1 > P and reject. for P > Pm, compute P , etc. 
With integers, Midpoint Subdivision requires only addition, right shift (/ 2). So it is a good method if perform clipping after viewing transformation to PDC (use integers). But it is not efficient for clipping against window (floating point numbers).
Advantages of clipping against window:
But a disadvantage is that we must do real number arithmetic and division and hence, it is slower.
Last changed May 13, 1998, G. Scott Owen, owen@siggraph.org