03/28/2002
15-462 Graphics I
23
Details of Painter’s Algorithm
•Each
face has form Ax + By + Cz + D
•Plug
in coordinates and determine
–Positive:
front side
–Zero:
on plane
–Negative:
back side
•Back-to-front:
inorder traversal, farther child first
•Front-to-back:
inorder traversal, near child first
•Do
backface culling with same sign test
•Clip
against visible portion of space (portals)
•[Guest Lecture:
John Ketchpaw]