[SOLVED] Stuck at "The color when a ray hits"

Hello,

I have all tests passing up until page 97.

I then run into this error on "The color when a ray hits" :


 Scenario: The color when a ray hits             # features/world.feature:56
   Given w ← default_world()                     # features/steps/world_steps.py:62 0.000s
   And r ← ray(point(0, 0, -5), vector(0, 0, 1)) # features/steps/spheres_steps.py:9 0.000s
   When c ← color_at(w, r)                       # features/steps/world_steps.py:138 0.013s
   Then c = color(0.38066, 0.47583, 0.2855)
     
     Captured stdout:
     0.36494287900649 0.4538741139549163 0.27601164405806367

As you can see my color is .36, .45, .27 making it off by a very small margin of about .1

If I increase my EPSILON to 0.1 then the tests all pass, but I believe we are not supposed to do that, and I don't see why that would make sense in this case.

What could I possibly be doing wrong that could cause such a small error, but still have all my other tests pass up to page 97, including "The color with an intersection behind the ray"

Any tips appreciated.

Nate

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Here are some of my relevant functions:


def lighting(material, light, point, eyev, normalv):
   effective_color = material.color * light.intensity
   lightv = normalize(light.position - point)
   ambient = effective_color * material.ambient
   light_dot_normal = dot(lightv, normalv)
   black = color(0, 0, 0)
   if light_dot_normal < 0:
       diffuse = black
       specular = black
   else:
       diffuse = effective_color * material.diffuse * light_dot_normal
       reflectv = reflect(-lightv, normalv)
       reflect_dot_eye = dot(reflectv, eyev)
       if reflect_dot_eye <= 0:
           specular = black
       else:
           factor = reflect_dot_eye ** material.shininess
           specular = light.intensity * material.specular * factor
   return ambient + diffuse + specular

def shade_hit(world, comps):
   return lighting(comps.object.material, world.light, comps.point, comps.eyev, comps.normalv)

def color_at(world, ray):
   xs = intersect_world(world, ray)
   if len(xs) == 0:
       return color(0, 0, 0)
   else:
       for i in xs:
           print(i.t)
           if i.t > 0:
               comps = prepare_computations(i, ray)
               print(comps)
               return shade_hit(world, comps)
   return color(0, 0, 0)

def default_world():
   w = world()
   w.light = point_light(point(-10, 10, -10), color(1, 1, 1))
   s1 = sphere()
   s1.material.color = color(0.8, 1.0, 0.6)
   s1.material.diffuse = 0.7
   s1.material.specular = 0.2
   w.objects.append(s1)
   s2 = sphere()
   s2.transform = scaling(0.5, 0.5, 0.5)
   w.objects.append(s2)
   return w

def intersect_world(world, ray):
   s = []
   for o in world.objects:
       i = intersect(o, ray)
       if len(i) != 0:
           for j in i:
               s.append(j)
   s = sorted(s, key=lambda x: x.t)
   return s