raytracing – Ray tracing Bug with Diffuse material

I am trying to do ray tracing in python (following the tutorial given in Ray Tracing in a weekend). Basically I am shooting rays from eye and the recursively bounce around, each time they hit something they become weaker (actually this is reverse ray casting but you get the idea). The output I am getting is incorrect.

My output:

bug1

Expected output:

expected

The shadows are messed up. What could be wrong?

My code:

import numpy as np
import sys
import random
from PIL import Image
from math import * 
from util import *

width  = 60
height = 60

samples = 20

#-----------------------------------------------------------------------

def reflected(vector, axis):
    return vector - axis * 2 * vector.dot(axis)


def RandomPointInSphere():
    p = None
    while True:
        p = Vector(random.uniform(0,1),random.uniform(0,1),random.uniform(0,1))*2 - Vector(1,1,1)
        if(p.dot(p) < 1):
            break
    return p

    
def GetNearestObject(objects, ray):
    nearest_obj = None
    min_hit = Intersection(None, INF, None, None)
    
    for obj in objects:
        hit = obj.intersect(ray)
        if(hit.distance < min_hit.distance):
            nearest_obj = obj
            min_hit = hit
    
    return min_hit
    

#-----------------------------------------------------------------------

def RayColor(objects, ray):
    # Part 1: Diffuse Material
    result = GetNearestObject(objects, ray)
    if(result.point != None):
        P = result.point
        N = result.normal
        E = RandomPointInSphere()
        target = P + N + E
        
        newRay = Ray(ray.origin, (target - ray.origin).normalize())
        return RayColor(objects, newRay)*0.5
    else:
        t = 0.5 * (ray.direction.y + 1.0);
        color = Vector(1.0, 1.0, 1.0)*(1.0 - t) + Vector(0.5, 0.7, 1.0)*t
        color.x = min(color.x,1.0)
        color.y = min(color.y,1.0)
        color.z = min(color.z,1.0)
        return Vector(1,1,1)
    
#-----------------------------------------------------------------------
def main():
    global bitmap
    
    eye    = Vector(0,0,1)
    ratio  = float(width) / height
    screen = Screen(-1, 1 / ratio, 1, -1 / ratio, 0)
    
    objects = ()
    objects.append(Sphere(Vector(-0.2,0,-1),  0.7, Material(Vector(0.1,0,0),  Vector(0.7,0,0),    Vector(1,1,1), 100, 0.5)))
    
    objects.append(Sphere(Vector(0,-9000,0),  9000-0.7, Material(Vector(0.1,0.1,0.1),Vector(0.6,0.6,0.6),Vector(1,1,1), 100, 0.5)))
    
    light = Light(Vector(5,5,5), Material(Vector(1,1,1),Vector(1,1,1),Vector(1,1,1)))
    
    for frame in range(1):
    
        img    = Image.new(mode = "RGB", size=(width, height), color=Color.WHITE)
        bitmap = img.load() # create the pixel data

#--------------------------------------------------------------
#---                    YOUR CODE HERE                      ---
#--------------------------------------------------------------
        sys.setrecursionlimit(10000)
        
        #breakpoint()
        
        deltaX = (screen.right - screen.left)/(width-1)
        deltaY = (screen.top - screen.bottom)/(height-1)

        for y in range(height):
            for x in range(width):
                pixel     = Vector(screen.left+x*deltaX, screen.top-y*deltaY, screen.z)
                direction = (pixel - eye).normalize()
                pixelRay = Ray(eye, direction)                

                # Part 1: Diffuse Material
                color = Vector(0,0,0)
                for s in range(samples):
                    color += RayColor(objects, pixelRay)
                
                color *= 1.0/samples
                #color = Vector(sqrt(color.x), sqrt(color.y), sqrt(color.z))
                bitmap(x,y) = (int(color.x*255), int(color.y*255), int(color.z*255))

            print("progress: %d %%" % ((y+1)/height*100.0))
            
#--------------------------------------------------------------
#--------------------------------------------------------------
#--------------------------------------------------------------

        img.show()
        img.save("pic1.png")
        #img.save("images/fig" + f'{frame:06}' + ".png")
        #print("Saving ---> images/fig" + f'{frame:06}' + ".png")
        #img.close()

main()
```