Python 2d ray tracing

LICENSE

The MIT License

Copyright (c) 2015 Hawker

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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THE SOFTWARE.

raytracer.py

import numpy as np

def _range_when_zero(iterlist):
    for i, pixel in enumerate(iterlist):
        if pixel == 0:
            return i
    else:
        return float(len(iterlist))


def _count_step(d_x, d_y, x, y, i, sina, minim):
    if minim == 1:
        return np.floor(sina*i), i
    else:
        return i, np.floor(i/sina)

def _range_when_non_zero(d_x, d_y, x, y, tab):
    maxval = max(d_x, d_y)
    sina = d_x/float(d_y)
    minim = (d_x, d_y).index(maxval)
    for i in xrange(maxval):
        step_x, step_y = _count_step(d_x, d_y, x, y, i, sina, minim)
        value = tab[y+step_y, x+step_x, 0]
        if value == 0:
            return np.sqrt(step_x**2 + step_y**2)
    return np.sqrt(d_x**2 + d_y**2)

def trace_ray(tab, start, end):
    x0, y0 = map(int,start)
    x1, y1 = map(int,end)
    d_x = x1 - x0
    d_y = y1 - y0
    if d_x == 0:
        ym = (y0,y1)
        return _range_when_zero(iterlist=tab[min(ym):max(ym), x0, 0])
    elif d_y == 0:
        xm = (x0,x1)
        return _range_when_zero(iterlist=tab[y0, min(xm):max(xm), 0])
    else:
        return _range_when_non_zero(d_x, d_y, x0, y0, tab)