COMPUTER GRAPHICS - DDA ALGORITHM !!

Digital Differential Analyzer (DDA) algorithm is the simple line generation algorithm.

Step 1 − Get the input of two end points (X₀,Y₀) and (X₁,Y₁).

Step 2 − Calculate the difference between two end points.

                dx = X₁ - X₀

                dy = Y₁ - Y₀

Step 3 − Based on the calculated difference in step-2, you need to identify the number of steps to put pixel. If dx > dy, then you need more steps in x coordinate; otherwise in y coordinate.

            if (absolute(dx) > absolute(dy))

               Steps = absolute(dx);

            else

               Steps = absolute(dy);

Step 4 − Calculate the increment in x coordinate and y coordinate.

                Xincrement = dx / (float) steps;

                Yincrement = dy / (float) steps;

Step 5 − Put the pixel by successfully incrementing x and y coordinates accordingly and complete the drawing of the line.

            for(int i=0; i < Steps; i++)

            {

               x = x + Xincrement;

               y = y + Yincrement;

               putpixel(Round(x), Round(y));

            }




// C program for DDA line generation

#include<stdio.h>

#include<graphics.h>

//Function for finding absolute value

int abs (int n)

{

    return ( (n>0) ? n : ( n * (-1)));

}

//DDA Function for line generation

void DDA(int X0, int Y0, int X1, int Y1)

{

    // calculate dx & dy

    int dx = X1 - X0;

    int dy = Y1 - Y0;

    // calculate steps required for generating pixels

    int steps = abs(dx) > abs(dy) ? abs(dx) : abs(dy);

    // calculate increment in x & y for each steps

    float Xinc = dx / (float) steps;

    float Yinc = dy / (float) steps;

    // Put pixel for each step

    float X = X0;

    float Y = Y0;

    for (int i = 0; i <= steps; i++)

    {

        putpixel (X,Y,RED);  // put pixel at (X,Y)

        X += Xinc;           // increment in x at each step

        Y += Yinc;           // increment in y at each step

        delay(100);          // for visualization of line-

                             // generation step by step

    }

}

// Driver program

int main()

{

    int gd = DETECT, gm;

    // Initialize graphics function

    initgraph (&gd, &gm, "");  

    int X0, Y0, X1, Y1;

cin>>X0,Y0,X1,Y1;

    DDA(-50, -50, 200, 200);

    return 0;

}

OUTPUT:-

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