Scan Converting a Straight Line

Scan Converting a Straight Line

Scan Converting a Straight Line Have you struggled with straight lines in graphics programming? You have company. Scanning lines seems straightforward, but it can get complicated quickly. There are many algorithms, each with pros and cons. Which ones work best and how can you apply them? We’ll look after you. We’ll demonstrate Xiaolin Wu’s line algorithm, Bresenham’s approach, and Wu’s algorithm, the three most popular line rendering algorithms. By the end, drawing straight lines will be easy and you’ll wonder why it took so long. Watch me launch my preferred graphics library and integrated development environment.

Scan Converting a Straight Line
Scan Converting a Straight Line

Understanding Scan Conversion of Lines

Knowing what scan conversion is can help you grasp scan conversion of lines. In order for raster displays, such as computer monitors, to display geometrical forms like lines, circles, and polygons, scan conversion is necessary.

For straight line scan conversion, the key is determining which pixels should be turned on to represent the line on the grid of pixels that make up your screen. ###Bresenham’s Line Algorithm

One of the most common ways to scan convert a line is Bresenham’s line algorithm. This figures out which pixels to illuminate by calculating the line’s slope and seeing which grid points the line passes through.

Coordinates (2, 2) to (8, 6). Dividing (6-2) by (8-2) yields 4/6, the slope, 2/3. Start activating the pixel at (2,2). If the distance from (2,2) to (3,3), 2/3 times 1, is greater than 1, the line must pass through (3,3). Activate (3,3) since it is. Activate switches (4,4), (5,5), and (6,6).

For the final points, round the slope up or down. Here, round 2/3 up to 1, so turn on (7,6), (8,6). And you have your line! Using this algorithm, you can scan convert any straight line on a raster display. With some modifications, you can also handle edge cases like vertical, horizontal or diagonal lines.

The key to understanding scan conversion of lines is seeing how mathematic algorithms can convert the abstract into the discrete pixels of a computer screen. With a little geometry and logic, you’ll be converting lines in no time!

Choosing the Right Scan Conversion Method

Scan Converting a Straight Line
Scan Converting a Straight Line

When it comes to scan converting straight lines, you’ve got a few options to choose from. The method you go with depends on things like complexity, precision, and optimization.


The simplest approach is rasterization. This converts the line into a series of pixels that roughly follow the line’s path. It’s fast and easy to implement but lacks precision.

Bresenham’s Algorithm

A popular choice for scan conversion is Bresenham’s algorithm. This uses integer math to plot the closest pixels to the true line path, making it more precise than rasterization while still being quite efficient. It’s a great all-purpose solution for most basic line rendering.

Wu’s Algorithm

For higher quality line rendering, you can use an anti-aliasing method like Wu’s algorithm. This employs fractional pixel coverage to produce smoother, less jagged lines. Wu’s algorithm is more complex but gives much nicer results, especially for lines at shallow angles.

Other Options

There are additional scan conversion methods like diagonal stroke, DDA, and vector plotting algorithms. These provide varying levels of complexity and quality. Diagonal stroke is very simple but low quality, DDA is in the middle, and vector plotting produces the highest quality but is the most complex.

In the end, you need to weigh factors like implementation difficulty, precision requirements, and rendering performance to determine the optimal scan conversion method for your needs. With so many options, there’s sure to be one that fits the bill!

Step-by-Step Process for Scan Converting Straight Lines

To scan convert a straight line, follow these steps:

1. Determine the line equation

To begin drawing a straight line, you must first determine its equation. In a straight line, the slope (m) and the y-intercept (b) are the variables that make up the equation y=mx+b.

2. Calculate the slope

The slope tells you how steep the line is. Find two points on the line and calculate the rise/run between them. For example, if the points are (2,3) and (5,7), the rise is 7-3=4 and the run is 5-2=3. So the slope is 4/3.

3. Find the y-intercept

The y-intercept is where the line crosses the y-axis. Substitute x=0 into the line equation to find the y-intercept. For example, if the equation is y=2x+5, then y=2(0)+5=5. So the y-intercept is (0,5).

4. Determine which octant the line is in

Look at the signs of the slope and y-intercept to determine which octant the line is in. The octants are numbered 1 through 8, starting at the upper right and going clockwise. For example, a line with a positive slope and positive y-intercept would be in octant 1.

5. Draw the line

Now you have all the information needed to scan convert the straight line. Starting from the y-intercept, use the slope to determine the next point on the line. Draw line segments connecting the points. Continue calculating points and drawing line segments until you reach the edge of the viewing window.

Following these steps carefully will allow you to scan convert any straight line. Let me know if you have any other questions!


The easy way to scan straight. Use these basic strategies to quickly draw straight lines on your screen. Though complicated, breaking it down simplifies things. First find the slope and line ends, then continue. Your new talent and precisely converted scan line are coming. Even as technology advances, knowing visuals can help you appreciate the amazing capabilities we now have. Grab a pencil and paper—your computer will do the rest!

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