DDA Algorithm

The digital drflerential analyzer (DDA) is a scan-conversion line algorithm.

This algorithm is summarized in the following procedure

1. Accept the two end points pixel positions as input.

   A(x₁, y₁)
   B(x₂, y₂)

   
   

2. Horizontal and vertical differences between the endpoint positions are assigned to parameters d_x and d_y.

   d_x = x₂ - x₁
   d_y = y₂ - y₁

   
   

3. The difference with the greater magnitude determines the value of parameter steps.

   if |d_x| > |d_y|      (compare absolute values of d_x and d_y)
       steps = d_x
   else
       steps = d_y

4. We determine the Incremental Factor needed at each step to generate the next pixel position along the line path.

   Δx = d_x ⁄ steps
   Δy = d_y ⁄ steps
   

5. Plot the initial points on the line

   x_new = x₁
   y_new = y₁
   

   setPixel ( x_new , y_new )

6. Generate new pixel on line by incrementing x and y, we repeat the process steps times.

   for (k = 0; k < steps; k++)
   

       x_new = x_new + Δx
       y_new = y_new + Δy
   

       setPixel ( x_new , y_new )