02/04/2003
15-462 Graphics I
29
Normals of Sphere
•
Implicit Equation f(x, y, z) = x
2
+ y
2
+ z
2
–1 = 0
•
Vector form: f(p) = p
¢
p – 1 = 0
•
Normal given by
gradient vector
•
•
•
•
•
Normalize n
0
/|n
0
| = 2p/2 = p
