Digital differential analyzer (graphics algorithm)

Digital Differential Analyzer (DDA)

DDA (digital differential analyzer) is used for generating pixels using a line formed by two points. It employees the equation for line representation (example: y=mx+c), then scan through an axis. Each scan it would determine the value on the other axis using the equation, this way the proper pixel can be located. Here is a sample C code of the DDA implementation:

Sample Code

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void line DDA(int xa, int ya, int xb, int yb)

{

           int dx=xb-xa, dy=yb-ya, steps, k;

           float xIncrement, yIncrement, x=xa, y=ya;

           if(abs(dx)>abs(dy)) steps=abs(dx);

           else steps=abs(dy);

           xIncrement=dx/(float)steps;

           yIncrement=dy/(float)steps;

           setPixel(ROUND(x), ROUND(y));

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

           {

                       x += xIncrement;

                       y += yIncrement;

                       setPixel(ROUND(x), ROUND(y));

           }

}