made it work. Now the image is properly rendered

It is useful to point out the rendering is _very_ slow.
I guess we can improve the situation, but soon we will have to switch to C

raytrace/World.py

@@ -1,8 +1,10 @@
 from . import ViewPlane
+from . import Ray
 from . import Tracer
 from . import samplers
 from PIL import Image
 import pygame
+import itertools
 import math
 import numpy
 import sys
@@ -12,9 +14,9 @@
 
 class World(object):
     def __init__(self):
-        self.viewplane = ViewPlane.ViewPlane(resolution=(500,200), pixel_size=1.0)
+        self.viewplane = ViewPlane.ViewPlane(resolution=(100,100), pixel_size=1.0)
         self.background_color = (0.0,0.0,0.0)
-        self.sampler = samplers.Regular(1)
+        self.sampler = samplers.Regular(9,10)
         self.objects=[]
 
     def set_bgcolor(self,bgcolor):
@@ -28,17 +30,18 @@ def render(self):
         tracer = Tracer.Tracer(self)
         for row in self.viewplane:
             for pixel in row:
+                print pixel
                 imagePxPos = (pixel[0], self.viewplane.resolution[1]-pixel[1]-1)
                 color = numpy.array([0.0, 0.0, 0.0])
-                for subsample in sampler:
+                for subsample in itertools.islice(self.sampler,self.sampler.num_samples_per_set()):
                     origin = numpy.zeros(3)
-                    origin[0] = self.viewplane.pixel_size*(column - self.viewplane.resolution[0] / 2 + subsample[0])
-                    origin[1] = self.viewplane.pixel_size*(row - self.viewplane.resolution[1] / 2 + subsample[1])
+                    origin[0] = self.viewplane.pixel_size*(pixel[0] - self.viewplane.resolution[0] / 2 + subsample[0])
+                    origin[1] = self.viewplane.pixel_size*(pixel[1] - self.viewplane.resolution[1] / 2 + subsample[1])
                     origin[2] = 100.0
                     ray = Ray.Ray(origin = origin, direction = (0.0,0.0,-1.0))
 
                     color += numpy.array(tracer.trace_ray(ray))
-                color /= sampler.num_samples
+                color /= self.sampler.num_samples_per_set()
 
                 im.putpixel(imagePxPos, (int(color[0]*255), int(color[1]*255), int(color[2]*255)))
                 pxarray[imagePxPos[0]][imagePxPos[1]] = (int(color[0]*255), int(color[1]*255), int(color[2]*255))
@@ -70,10 +73,6 @@ def f(o):
             return None
 
         return foremost
-
-
-
-        self.sampler = sampler.Regular(1)
 
     def set_sampler(self, sampler):
         self.sampler = sampler