>   However, I don't want to read lengthy books filled with material and
> lighting theory just to try this. If someone could write me a simple
> algorithm then I could try it.
> 

Well Scott did, and it's not all that difficult to perfect it to obtain 
the result you seek, i.e. to have different colors for diffusion and 
reflection.

color = 0
for ray=1 to 1000
r = random number between 0 and 1
a = specular_amount
b = specular_amount+diffuse_amount
c = specular_amount+diffuse_amount+refraction_amount

if 0 < r < a
  color += reflection_color * fire_reflection_ray

if a < r < b
  color += diffuse_color * fire_diffuse_ray_in_random_direction

if b < r < c
  color += refraction_color * fire_refraction_ray

if c<r<1.0 //absorption
  color += 0

//Of course you could have emitting surfaces as well
if emission
  color += emitted_color

next

pixel_color = color / 1000

The algorithm should check that c<1, obviously, otherwise the surface 
transmits more light than it receives.

The real problem with that approach, that you should have pointed out, 
is that the lights are missed most of the time if you don't fire rays to 
them specifically. If all your lights are point lights, they will always 
be missed.

With very simple BRDF such as these (specular + diffuse), you would only 
have to fire shadow rays in the diffuse case above. And possibly sample 
all visible emitting surfaces. I don't remember the details...

The other problem is deciding when you stop firing rays. If many 
surfaces have no absorption, it's possible to end up with very long 
paths... I think one of the books uses a form of Russian roulette to 
stop ray spawning and still keep an unbiased picture.

-- 
Vincent

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