Vincent Le Chevalier <gal### [at] libertyallsurfspamfr> wrote:
> As far as I understand, there is no mixing going on in these methods, 
> not at the ray level.

  There must be, because the surface can have its own color besides being
reflective and/or refractive.

  Let's assume that the surface is colored red and has a 50% of reflectivity.
If you simply calculate the reflective ray and it returns green, and you
return only this green to the camera ray, the red color of the surface has
been completely dropped. This would make the object 100% reflective, with
no own color.
  Naturally that's wrong. The red has to be mixed with the reflected color
somehow, to get a shade of yellow.

  Besides, the surface color is not only affected by its pigment, but also
by lighting. Where is that taken into account?

> You don't shoot one ray per pixel, you shoot many 
> of them, and make them bounce around surfaces or refract with 
> probabilities according to the transparency.

  I understood that, but I don't understand at which step the surface's
own coloring (affected by lighting) is taken into account.

> In your example, you would fire 100 rays, and have:
> ~80 that are refracted, and colored by the "transmitted" color of the 
> surface
> ~20 that are reflected, and colored by the "reflective" color of the surface

> In the end you average all the intensities, and you get, statistically, 
> the same result you'd get with a classical raytracer: 80% of refracted 
> ray color * "transmitted" color, 20% of reflected ray color * 
> "reflective" color.

  How about the surface's own color?

-- 
                                                          - Warp

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