
2.6 Vertex Attributes 97
If the observer looks at V in the direction U =−R, he should see a very bright region
at the point. As the view direction varies away from −R, the region at the point should
be less bright. The specular coefficient for the attenuation is chosen to be
γ = (max{−R
.
U,0})
M
shine
(2.80)
The clamping to zero means that an observer behind the surface will see no reflected
light. The exponent M
shine
controls how small (or large) the bright region is around
V. The specular lighting is
C
spec
= γ M
spec
◦ L
spec
(2.81)
The Blinn lighting equation [Bli77] is a variation of the Phong lighting equation.
Figure 2.36 (b) illustrates this model. The half ...