Bresenham Line Drawing Algorithm Code in Python

Bresenham Algorithm is an algorithm that uses integer values to determine the points lying between the starting and end points within the space. It is a type of incremental scan conversion algorithm for line drawing. It determines all the points lying between the starting and end points. The Bresenham Line Drawing algorithm uses different mathematical operations, including addition and subtraction. Still, it does not use multiplication and division, as these operations are heavy, resulting in slow processing of the lines.

Problem Statement

We need to draw a line AB. The coordinates of the points of lines are A (a1, b1) and B (a2, b2). We must find the points needed to draw the line on the AB on the screen of pixels.

Let's understand this problem statement using a few examples.

Examples:

Input:

Output:

 (1, 1), (2, 2), (3, 3), (4, 4), (5, 5) 

Input:

Output:

 (0, 0), (1, 0), (2, 1), (3, 2) 

Assumption in the Bresenham Line Drawing Algorithm

These are some assumptions to make the algorithm more simple:

• The lines must drawn from left to right.
• The coordinates of the points of the line must follow this rule: a1 < a2, and b1 < b2.
• The slope of the line made must be between 0 and 1.
• The line must be drawn from the lower left to the upper right.

How does the Bresenham Algorithm Work?

Implementation

The matplotlib library displays the lines made using the bresenham line drawing algorithm.

Code:

Output:

 Enter the Starting point of a: 23 Enter the Starting point of b: 34 Enter the end point of a: 45 Enter the end point of b: 44 a = 23, b = 34 a = 24, b = 34 a = 25, b = 35 a = 26, b = 35 a = 27, b = 36 a = 28, b = 36 a = 29, b = 37 a = 30, b = 37 a = 31, b = 38 a = 32, b = 38 a = 33, b = 39 a = 34, b = 39 a = 35, b = 39 a = 36, b = 40 a = 37, b = 40 a = 38, b = 41 a = 39, b = 41 a = 40, b = 42 a = 41, b = 42 a = 42, b = 43 a = 43, b = 43 a = 44, b = 44 a = 45, b = 44 

Explanation:

We imported the matplotlib library to show the lines. Using the title, xlabel, and ylabel functions, we labeled the title and labels of the graphs. The X and Y axis coordinates are declared with a and b variables, respectively. These are evaluated based on the slope error value, which is determined using the absolute value of a and b.