Difference Between DDA and Bresenham Line Drawing algorithm



The realm of computer graphics is an expansive one that is always undergoing development. It involves a variety of concepts and ideas, of which "drawing a line" is the most fundamental tasks involved in working with graphical media.

There are two algorithmic rules that are followed while drawing a line on the screen. They are DDA (Digital Differential Analyser) algorithmic rule and Bresenham line algorithm.

Both the DDA and Bresenham's algorithm are examples of computational procedures that can be utilised for the goal of approximating the length of a line segment.

What is DDA?

The primary purpose of a DDA in computer graphics is to draw lines, and it use real values while predicting the values of the following pixel. DDA is an abbreviation for "Digital Differential Analyzer."

Let us consider the value of the first pixel to be (X0, Y0) (X0, Y0), and the value of the pixel to be (X1, Y1) as the destination (X1, Y1).

In this article, we will learn how to compute the destination pixel values using the known pixel value (X0, Y0) (X0, Y0).

So, let's take an example and see how the pixel values of a destination point is calculated using DDA.

Step 1

Now that we have the input (X0, Y0) (X0, Y0), we need to determine if the line is perpendicular to the X-axis or the Y-axis. In order to find that, let's first calculate the difference in pixel values between the starting point and the final location.

dx = X1 - X0
dy = Y1 - Y0

Step 2

Next, start drawing the line down the X-axis. We should draw the line so that it is parallel to the Y-axis if and only if the value of "dx" is zero. This is the actual computation expressed in terms of the language used by computers.

if (absolute (dx) > absolute (dy))
   Steps = absolute (dx);
else
   Steps = absolute (dy);

Step 3

In order to draw the line, it is necessary to first determine the actual pixel values for the "x" coordinate and the "y" coordinate, respectively.

X increment = dx / (float) steps;
Y increment = dy / (float) steps;

Step 4

This is something that needs to be computed till we get to the goal pixel. During the computation, the DDA method will round the pixel value down to the nearest integer value. The sample of the code that we have been discussing can be found here.

for (int v=0; v < Steps; v++) {
   x = x + X increment;
   y = y + Y increment;
   putpixel (Round(x), Round(y));
}


What is Bresenham’s Algorithm?

In the field of computer graphics, the algorithm developed by Bresenham is among the earliest approaches that were developed to estimate line segments. It is used to define various places via which a straight line can be approximated drawn. The line can then be formed from those points. The vast majority of people use it to make straightforward geometric forms in bitmap graphics.

In contrast to DDA's usage of multiplication and division in its calculating process, Bresenham's method relies just on addition and subtraction to complete its tasks. This indicates that it makes use of simple computations, which results in the saving of time and demonstrates increased efficiency. In addition to this, it is extremely precise and accurate, making it one of the best methods for computing values. It enables optimization and is also quite inexpensive in comparison to other options.

The algorithm is utilized in a significant way across a variety of graphic chip and plotter applications. As a result of this, it serves as the foundation for a great deal of software graphic libraries. A lot of individuals make advantage of its extensions in order to create different kinds of shapes, such as spheres and circles. Because the computations are so straightforward, it is even incorporated into the software that runs on some graphic cards.

In spite of this, there have been a great many alterations made to the algorithm ever since its discovery in 1962. In the past, the only thing that could be drawn with it were simple lines and shapes. However, in this day and age, the algorithm may also be used to draw Bezier curves, cubes, and ellipses. Let's have a peek at the workings of this algorithm.

  • The algorithms developed by Bresenham make the assumption that the initial pixel coordinate is (xa+1, ya).

  • The next pixel value is automatically computed as (xa+1, ya+1), where an is the incremental value, and the algorithm computes it by either adding or removing the equations that it has created.

Difference between DDA and Bresenham’s Algorithm

The following table highlights the major differences between DDA and Bresenham's Algorithm −

Basis of comparison
DDA
Bresenham’s Algorithm
Method
Multiplication and division are the only operations used.
Only addition and subtraction are used in this process
Efficiency
In comparison to the Bresenham line algorithm, the DDA approach is not as efficient.
Despite the fact that it is more effective than the DDA algorithm.
Speed
The computation speed of the Bresenham line method is significantly higher than that of the DDA algorithm.
However, the computation speed of the Bresenham line algorithm is significantly faster than that of the DDA algorithm.
Precision
It does not have a high degree of accuracy or precision.
It's extremely accurate and precise.
Complexity
In order to complete its tasks, it relies on complex calculations.
In order to do its tasks, it performs basic calculations.
Price
It comes at a high cost.
It is on the lower end of the price range.
Optimization
It prevents optimization from happening.
It enables optimization.

Conclusion

Within the realm of computer graphics, the DDA and Bresenham's method serve very similar functions. Each of them can be used to create line segments as well as a variety of other things.

Bresenham's algorithm just uses addition and subtraction to accomplish this goal, whereas DDA relies on multiplication and division. DDA is a more complicated system that is also less efficient and not very precise. On the other hand, the method developed by Bresenham is straightforward, practical, and accurate to a reasonable degree.

One more significant distinction between the two is that DDA can frequently end up being more expensive despite the constraints of its use. As a result, it is possible that it is not the best answer for datasets that are more extensive. The approach developed by Bresenham, on the other hand, may be used to massive data sets while being significantly more cost-effective.


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