# Tk_ray_trace.py

# Tk_ray_trace.py

from Tkinter import *
from PIL import Image, ImageTk
import math

class vector:
    def __init__(self, x, y, z):
        self.x = x
        self.y = y
        self.z = z

def scan():
    radius = 0.5
    point = vector(0.0, 0.0, 0.0)
    fromvec = vector(0.0, -1.0, 3.0)
    to = vector(0.0, 0.0, -1.0)
    to = vector(0.0, 0.0, -1.0)
    while fromvec.y < 1.0:
        fromvec.x = -1.0
        while fromvec.x < 1.0:
            vec = vminus(fromvec, point)
            b = innerproduct(to, vec)
            c = innerproduct(vec, vec) - radius*radius
            d = b * b - c
            if d < 0: # ray is not intersect
                fromvec.x = fromvec.x + 2.0/200
                continue
            det = math.sqrt(d)
            t = -b + det
            if t < 0: # object is behind eye
                fromvec.x = fromvec.x + 2.0/200
                continue
            shading(t, fromvec, to, point)
            fromvec.x = fromvec.x + 2.0/200
        fromvec.y = fromvec.y + 2.0/200

def shading(t, fromvec, to, point):
    l = vector(0.577, -0.577, -0.577) # light normalize(1, -1, -1)
    ac = vector(0.1, 0.1, 0.1)        # ambient light color
    col = vector(1, 0, 0)             # color of an object
    too = vector(to.x * t, to.y * t, to.z * t)
    c = vplus(fromvec, too)
    c = vminus(c, point)
    c = normalize(c)
    val = innerproduct(c, l)
    r = int(255.0 * (col.x * val + ac.x))
    g = int(255.0 * (col.y * val + ac.y))
    b = int(255.0 * (col.z * val + ac.z))
    if r > 255:
        r = 255
    if g > 255:
        g = 255
    if b > 255:
        b = 255
    if r < 0:
        r = 0
    if g < 0:
        g = 0
    if b < 0:
        b = 0
    pic[int(fromvec.x*100+100)+(int(fromvec.y*100+100)*200)] = (r, g, b)

def vplus(a, b):
    return vector( a.x + b.x, a.y + b.y, a.z + b.z)

def vminus(a, b):
    return vector( a.x - b.x, a.y - b.y, a.z - b.z)

def innerproduct(a, b):
    return a.x * b.x + a.y * b.y + a.z * b.z

def normalize(a):
    s = a.x * a.x + a.y * a.y + a.z * a.z
    d = math.sqrt(s)
    return vector(a.x/d, a.y/d, a.z/d)

sq = 200
pic = [(100,100,100) for z in range(sq*sq)]
scan()
root = Tk()
root.title("Tk Ray Trace")
root.geometry("%dx%d+0+0"%(sq,sq))
canvas = Canvas(root, width=sq, height=sq)
canvas.grid()
img = Image.new("RGB",(sq, sq))
img.putdata(pic)
imgTk = ImageTk.PhotoImage(img)
canvas.create_image(0, 0, anchor=NW, image=imgTk)
canvas.update()