02/04/2003
15-462 Graphics I
27
Normals of a Plane, Method I
•Method
I: given by ax + by + cz + d = 0
•Let p0 be a known point on the plane
•Let p
be an arbitrary point on the plane
•Recall:
u ¢ v = 0 iff u orthogonal v
•n ¢ (p – p0) = n¢ p – n¢
p0 = 0
•Consequently
n0 = [a
b c 0]T
•Normalize
to n = n0/|n0|