Total refraction bounces as surface color

[mightcouldb1]

Hey guys,

I understand the refract function returns a refraction vector.  The refractlight function returns a color.  I would like to store the number of refraction bounces as the final surface color, or perhaps the length the ray traveled.  Can anyone help me understand how this works for multiple bounces?

Best,
Jason

[rsd]

Try to set Cf = getraylevel().

[mightcouldb1]

Awesome thanks for that!  Can anyone post a snippet of code for multiple bounce refraction?  Say I had an complex surface that had multiple refractions and I wanted to know the distance that the 6th ray bounce traveled.  I'm assuming I would have to handle this with the rayhittest()?

 

Thanks!

[rsd]

There is simple shader.

By default it shows the number of bounces of last hit. Toggle raylength on to show length of the last ray.

Play with refract limit to get desired level.

#pragma hint last invisible
#pragma hint raylength toggle

surface
bounces(float ior = 1.46;
        int raylength = 0;
        export float last = 0)
{
    if (raylength)
        last = length(I);
    else
        last = getraylevel();


    vector ni = normalize(I);
    vector nn = normalize(N);
    vector tdir = refract(ni, nn, 1./ior);

    Cf = 0;
    float imported;
    if (trace(P, tdir, Time,
              "samplefilter", "closest",
              "last", imported))
        last = imported;

    Cf = last;
}

bounce_test1.hiplc

Edited November 18, 2014 by rsd

[mightcouldb1]

Thank you, this is very helpful.  Very much appreciated!