In [5]:

    

from __future__ import division

import numpy as np
from numpy import *

import matplotlib.pyplot as plt
%matplotlib inline
import seaborn as sns


    

In [6]:

    

class bresenham_diff:    
    '''
    Bresenham's algorithm
    Input: Takes starting point (p0) and endpoint (p1).
    Output: set of pixel coordinates, or matrix with pixels filled in
    TODO: add option to thicken lines, add option to gaussian blur
    
    resource: http://floppsie.comp.glam.ac.uk/Glamorgan/gaius/gametools/6.html
    see also: https://github.com/encukou/bresenham
    but this is a actually WAY stripped down implementation purged of if-blocks
    '''
    def __init__(self, p0, p1):
        self.initial = True
        self.end = False
        self.p0 = p0
        self.p1 = p1
        self.x0 = p0[0]
        self.y0 = p0[1]
        self.x1 = p1[0]
        self.y1 = p1[1]
        self.dx = abs(self.x1-self.x0) 
        self.dy = abs(self.y1-self.y0)
        self.slope = self.dy/self.dx
        self.sign = np.sign(self.slope)
        self.xpix = []
        self.ypix = []
        self.imsize = 250
        
    def walk_along(self):
        '''
        intuition: increment by x pixel, and fill in the closest y pixel as you go

        '''
        self.xpix = np.linspace(int(self.x0),int(self.x1),abs(self.dx)+1)
        for _y in np.linspace(self.y0,self.y1,abs(self.dx)+1):
            self.ypix.append(np.round(_y))            
        return self.xpix, self.ypix
    
    def fillgrid(self,xpix,ypix):
        mat = np.tile(0,(self.imsize,self.imsize))
        for _x,_y in zip(xpix,ypix):
            mat[int(_x),int(_y)] = 250                
        return mat
    
    ## add option to thicken lines
    
    ## add option to gaussian blur


    

In [7]:

    

start = [0,0]
end = [200,-180]
l = bresenham_diff(start,end)
xpix,ypix = l.walk_along()
mat = l.fillgrid(xpix,ypix)


    

In [9]:

    

sns.set_style('whitegrid')
plt.matshow(mat)


    

    
Out[9]:





<matplotlib.image.AxesImage at 0x112dee090>






    

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