Getting diffuse material right form cpu code to gpu shader - c++

Question

I'm trying to unwarp this function from raytracing in one weekend
vec3 color(const ray& r, hitable *world)
{
hit_record rec;
if(world->hit(r,0.0, MAXFLOAT, rec)){
vec3 target = rec.p + rec.normal + random_in_unit_sphere();
return 0.5*color( ray(rec.p, target-rec.p), world);
}
else{
vec3 unit_direction = unit_vector(r.direction());
float t = 0.5*(unit_direction.y() + 1.0);
return (1.0-t)*vec3(1.0,1.0,1.0) + t*vec3(0.5,0.7,1.0);
}
}
i've understand that it will send a ray and bounce it until it does not hit anything.
So i have attempt to unwarp this recursive function in a GLSL shader.
vec3 color(ray r, hitableList list)
{
hitRecord rec;
vec3 unitDirection;
float t;
while(hit(r, 0.0, FLT_MAX, rec, list))
{
vec3 target = rec.p + rec.normal;
r = ray(rec.p, target-rec.p);
}
unitDirection = normalize(direction(r));
t = 0.5* (unitDirection.y + 1.);
return (1.-t)*vec3(1.)+t*vec3(0.5,0.7,1.);
}
normally it should output a diffuse like this :
but i only get a reflective material like this :
note, the material is HIGHLY reflective and can reflect other sphere in the scene.
i have looked around the code and something tell me it's my wrong approche of this tail recursive fonction. Also I don't return the 0.5 * the return 0.5 * color(...) I have no idea how to do it.
UPDATE
Thanks to the awnser of Jarod42 there is now the 0.5 * factor implemented, this solve the issue of the material not being "properly" expose to light.
But now the diffuse material is still not generated, I end up with a Metal Material fully reflective.

Answer 1

To use the factor of 0.5, you might do something like:
vec3 color(ray r, hitableList list)
{
hitRecord rec;
vec3 unitDirection;
float t;
float factor = 1.f;
while(hit(r, 0.0, FLT_MAX, rec, list))
{
vec3 target = rec.p + rec.normal;
r = ray(rec.p, target-rec.p);
factor *= 0.5f;
}
unitDirection = normalize(direction(r));
t = 0.5* (unitDirection.y + 1.);
return factor * ((1.-t)*vec3(1.)+t*vec3(0.5,0.7,1.));
}