Clipping

Before clipping…

After clipping…

Point Clipping Display P = (x, y) if xw min <= x <= xw max yw min <= y <= yw max

Line Clipping Display P = (x, y) if xw min <= x <= xw max yw min <= y <= yw max Line Clipping If both points lie inside the window display segment

Line Clipping (cont) Display P = (x, y) if xw min <= x <= xw max yw min <= y <= yw max Line Clipping If both points lie inside the window display segment If both points lie outside the same boundary discard segment

Line Clipping (cont) Display P = (x, y) if xw min <= x <= xw max yw min <= y <= yw max If both points lie inside the window display segment If both points lie outside the same boundary discard segment If segment crosses one or more boundaries calculate intersections with boundaries x = x 1 + u(x 2 - x 1 ) y = y 1 + u(y 2 - y 1 ) if 0 <= u <= 1 display section within boundary else discard segment

Cohen - Sutherland Line Clipping 4 bit clip code: A B R L

Cohen - Sutherland Line Clipping (cont) 4 bit clip code: A B R L A = y > yw max B = y < yw min R = x > xw max L = x < xw min

4 bit clip code: A B R L A = y > yw max B = y < yw min R = x > xw max L = x < xw min Calculate clip code P 1 = P 2 = => accept segment P 1 P 2 (trivial accept since both end points are in the window

4 bit clip code: A B R L A = y > yw max B = y < yw min R = x > xw max L = x < xw min Calculate clip code P3 = P4 = => Reject segment P3 P4