20th August, 2023
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# Drawing Lines Using DDA Algorithm in C Graphics - Step-by-Step Guide

Drawing lines is a fundamental task in computer graphics. The Digital Differential Analyzer (DDA) algorithm is a straightforward method to draw lines on a computer screen. In this tutorial, we'll guide you through implementing the DDA line drawing algorithm in C using graphics.h library. Follow this step-by-step guide to create your own line drawing program!

Step 1: Setting Up Environment:

Before we start, make sure you have a C compiler installed along with the graphics.h library. You can use Turbo C or Code::Blocks IDE for ease.

Step 2: Include Necessary Libraries:

#include <stdio.h>
#include <conio.h>
#include <graphics.h>

**Step 3: Main Function:**

int main() {
int gd = DETECT, gm;
initgraph(&gd, &gm, "C:\\Turboc3\\BGI");
int x1, y1, x2, y2;
printf("Enter coordinates of the first point (x1 y1): ");
scanf("%d %d", &x1, &y1);
printf("Enter coordinates of the second point (x2 y2): ");
scanf("%d %d", &x2, &y2);
int dx = x2 - x1;
int dy = y2 - y1;
float steps = abs(dx) > abs(dy) ? abs(dx) : abs(dy);
float xIncrement = dx / steps;
float yIncrement = dy / steps;
float x = x1;
float y = y1;
for (int i = 0; i <= steps; i++) {
putpixel(round(x), round(y), WHITE);
x += xIncrement;
y += yIncrement;
}
getch();
closegraph();
return 0;
}

Step 4: Explanation:

- We initialize the graphics mode using
**initgraph()** with DETECT and gm as graphics mode. - Users input the coordinates of the two endpoints of the line.
- We calculate the differences in x and y values (
**dx** and **dy**). **steps** determine the number of points to plot; it's the maximum of absolute **dx** and **dy**.**xIncrement** and **yIncrement** calculate how much to increment **x** and **y** for each step.- We then iterate from 0 to
**steps**, plotting each point using **putpixel()**. - After plotting, we wait for a key press using
**getch()**, and then close the graphics window.

In this tutorial, we've walked through the process of implementing the Digital Differential Analyzer (DDA) line drawing algorithm in C using the graphics.h library. By following the steps outlined in this guide, you've gained a solid understanding of how to create a basic line drawing program.