02/11/2003
15-462 Graphics I
3
Explicit Representation
•Curve
in 2D: y = f(x)
•Curve
in 3D: y = f(x), z = g(x)
•Surface
in 3D: z = f(x,y)
•Problems:
–How
about a vertical line x = c as y = f(x)?
–Circle
y = § (r2 – x2)1/2 two or zero values for x
•Too
dependent on coordinate system
•Rarely
used in computer graphics