Advantages of DDA Algorithm

• It is a simple and easy-to-implement algorithm.
• It avoids using multiple operations which have high time complexities.
• It is faster than the direct use of the line equation because it does not use any floating point multiplication and it calculates points on the line.

Introduction :

DDA (Digital Differential Analyzer) is a line drawing algorithm used in computer graphics to generate a line segment between two specified endpoints. It is a simple and efficient algorithm that works by using the incremental difference between the x-coordinates and y-coordinates of the two endpoints to plot the line.

The steps involved in DDA line generation algorithm are:

1. Input the two endpoints of the line segment, (x1,y1) and (x2,y2).
2. Calculate the difference between the x-coordinates and y-coordinates of the endpoints as dx and dy respectively.
3. Calculate the slope of the line as m = dy/dx.
4. Set the initial point of the line as (x1,y1).
5. Loop through the x-coordinates of the line, incrementing by one each time, and calculate the corresponding y-coordinate using the equation y = y1 + m(x – x1).
6. Plot the pixel at the calculated (x,y) coordinate.
7. Repeat steps 5 and 6 until the endpoint (x2,y2) is reached.

DDA algorithm is relatively easy to implement and is computationally efficient, making it suitable for real-time applications. However, it has some limitations, such as the inability to handle vertical lines and the need for floating-point arithmetic, which can be slow on some systems. Nonetheless, it remains a popular choice for generating lines in computer graphics.

In any 2-Dimensional plane, if we connect two points (x0, y0) and (x1, y1), we get a line segment. But in the case of computer graphics, we can not directly join any two coordinate points, for that, we should calculate intermediate points’ coordinates and put a pixel for each intermediate point, of the desired color with the help of functions like putpixel(x, y, K) in C, where (x,y) is our co-ordinate and K denotes some color.

Examples: 

Input: For line segment between (2, 2) and (6, 6) :
Output: we need (3, 3) (4, 4) and (5, 5) as our intermediate points.

Input: For line segment between (0, 2) and (0, 6) :
Output: we need (0, 3) (0, 4) and (0, 5) as our intermediate points.

For using graphics functions, our system output screen is treated as a coordinate system where the coordinate of the top-left corner is (0, 0) and as we move down our y-ordinate increases, and as we move right our x-ordinate increases for any point (x, y). Now, for generating any line segment we need intermediate points and for calculating them we can use a basic algorithm called DDA(Digital differential analyzer) line generating algorithm.