Motorola DSP96002 User Manual page 586

R Direction vector of reflection of the point source from the
object R={Rx,Ry,Rz}
V Direction vector from the object to the viewpoint
Ks Specular reflection constant 0<= Ks <= 1.0
It should be noted that all vectors are normalized to unit magnitude.
The illumination can be described several ways depending on the complexity of the object and light source:
I=Ip Kd L * N
I=Ia Ka + Ip Kd L * N Ambient lighting and diffuse reflection
I=Ia Ka + Ip(Kd L * N + Ks(R * V) ** n)
In the above equations, * represents a vector dot product such as L * N = LxNx+LyNy+LzNz and ** repre-
sents exponentiation.
Since the dot product of two normalized vectors is less than or equal to one, the term Ks(R * V) ** n is less
than one. The value of this term is found by using a 256 element lookup table with 256.0(R * V) as an index.
The value of n is an arbitrary term that is fixed for the algorithm and depends on empirical conditions.
vec R0
ktbl R4
MOTOROLA
Diffuse reflection
Ambient lighting, diffuse reflection and
specular reflection (Phong model)
X memory Y memory
Rx
Ry
Rz
Lx
Ly
Lz
256.0
address of spctbl
Kd
Ip
Ia
Ka
DSP96002 USER'S MANUAL
Vx
Vy
Vz
Nx
Ny
Nz
B-67