rainbow/rainbow.py

import numpy as np
from raytrace_2D import Disk
import csv

class Ray:
	def __init__(self, origin, direction, intensity):
		self.origin = np.array(origin)
		self.direction = np.array(direction) / np.linalg.norm(direction)
		self.intensity = intensity

center = [0,0]
r = 1
n = 1.3
disk = Disk(center, r, n)
dx = 0.005
N = int(2*r /dx - 1)
min_intensity = 0.001
max_ray = 10000

stack = []
result = []
points = []

def init():
	for x in np.linspace(-r + dx, r-dx, N):
		stack.append(Ray([x, 2*r], [0,-1], 10*np.abs(x)))
	print(np.linspace(-r + dx, r-dx, N))

def reflection_and_refraction(ray:Ray, intersection_point, normal, n):
	# print("reflection/refraction at the point:", intersection_point)
	k_n = np.dot(ray.direction, normal)
	if k_n > 0:
		n1,n2 = n,1
	else:
		n1, n2 = 1,n
	kp = ray.direction - k_n*normal
	k2p = n1*kp/n2
	if np.dot(k2p, k2p) >= 1:
		ray1 = Ray(intersection_point, ray.direction-2*k_n*normal, ray.intensity)
		return ray1,None
	else:
		k2n = np.sqrt(1 - np.dot(k2p, k2p))*np.sign(k_n)
		Rs = (n1*k_n - n2*k2n)*(n1*k_n - n2*k2n)/((n1*k_n + n2*k2n)*(n1*k_n + n2*k2n))
		Rp = (n1*k2n - n2*k_n)*(n1*k2n - n2*k_n)/((n1*k2n + n2*k_n)*(n1*k2n + n2*k_n))
		R = (Rs+Rp)/2
		ray1 = Ray(intersection_point, ray.direction-2*k_n*normal, ray.intensity*R)
		ray2 = Ray(intersection_point, k2n*normal+k2p, ray.intensity*(1-R))
		return ray1,ray2

def trace(disk:Disk, stack:list, max_ray:int):
	ray_count = 0
	while stack and ray_count < max_ray:
		ray = stack.pop()
		ray_count += 1
		if ray is None:
			continue
		if isinstance(ray, Ray):
			if ray.intensity < min_intensity:
				continue
			direction = ray.direction
			t,intersection_point = disk.find_intersection(ray)
			if intersection_point is not None:
				points.append(np.concatenate((ray.origin, intersection_point,[ray.intensity])))
				normal = disk.get_normal(intersection_point)
				stack.extend(reflection_and_refraction(ray, intersection_point, normal, disk.refractive_index))
			else:
				points.append(np.concatenate((ray.origin, ray.origin+ray.direction,[ray.intensity])))
				if direction[1] > 0:
					result.append([np.arccos(direction[1]), ray.intensity*direction[1]])
	print("ray trace finish, total ray count:",ray_count)

def water_density(t):
	data_t = np.linspace(0,101,102)
	data_rho = np.array([999.79,999.84,999.88,999.92,999.97,999.92,999.88,999.84,999.79,999.72,999.65,999.55,999.44,999.32,999.19,999.05,998.90,998.74,998.56,998.36,998.16,997.96,997.74,997.50,997.25,996.99,996.74,996.48,996.20,995.90,995.59,995.29,995.97,994.65,994.33,994.98,993.64,993.28,992.93,992.55,992.17,991.78,991.39,990.99,990.57,990.16,989.75,989.33,988.90,988.45,988.04,987.55,987.06,986.58,986.19,985.70,985.22,984.73,984.67,983.18,983.13,982.70,982.22,981.64,981.06,980.48,979.91,979.33,978.85,978.28,977.70,977.13,976.56,975.99,975.41,974.84,974.27,973.70,973.14,972.47,971.81,971.25,970.59,969.93,969.27,968.61,967.96,967.30,966.65,965.99,965.34,964.69,964.04,963.39,962.64,961.90,961.26,960.52,959.78,959.04,958.40,957.67])
	return np.interp(t, data_t, data_rho)

def water_refraction_index(t, wavelength):
	rhobar = 0.999974950 * (1 - (t - 3.983035)*(t - 3.983035)*(t + 301.797)/(522528.9*(t+69.34881)))
	print(rhobar)
	a0 = 0.244257733
	a1 = 0.00974634476
	a2 = -0.00373234996
	a3 = 0.000268678472
	a4 = 0.0015892057
	a5 = 0.00245934259
	a6 = 0.90070492
	a7 = -0.0166626219
	Tstar = 273.15
	Tbar = 1 + t/Tstar
	lambdastar = 589
	lambdabar = wavelength/lambdastar
	lambda_IR = 5.432937
	lambda_UV = 0.229202
	C = a0 + a1*rhobar + a2*Tbar + a3*lambdabar*lambdabar*Tbar + a4/(lambdabar*lambdabar) + a5/((lambdabar+lambda_UV)*(lambdabar-lambda_UV)) + a6/((lambdabar + lambda_IR)*(lambdabar - lambda_IR)) + a7*rhobar*rhobar
	C *= rhobar
	n = np.sqrt((2*C+1)/(1-C))
	return n