Question

my subject :Introduction to Computer Graphics

Problem #1

You need to write a program which implements both DDA and Bresenham’s Line Generation Algorithms.

The program should prompt the user to enter tow points coordinate and then compute and display the estimated coordinate of the line segment on the screen.

Example

Please enter your line segment starting point?

10

10

Please enter the coordinate of the line segment end point?

50

30

What algorithm to use

1. DDA
2. Bresenham’s

Your program should display he computed coordinates and a graphical image of the plotted line.

Answer 1

DDA line drawing algorithm

source code:

#include <graphics.h>
#include <math.h>
#include <dos.h>
void main( )
{
float x,y,x1,y1,x2,y2,dx,dy,step;
int i,gd=DETECT,gm;
initgraph(&gd,&gm,"c:\\turboc3\\bgi");
scanf("%f%f",&x1,&y1);
scanf("%f%f",&x2,&y2);
dx=abs(x2-x1); dy=abs(y2-y1);
if(dx>=dy) step=dx;
else step=dy;
dx=dx/step; dy=dy/step;
x=x1; y=y1; i=1;
outtextxy(x1-5,y1-5,"(x1,y1)");
outtextxy(x2+5,y2+5,"(x2,y2)");
while(i<=step)
{
putpixel(x,y,5); x=x+dx; y=y+dy; i=i+1; delay(60);
}
getch();
}
input:

10

10

50

30

output:

Input :

100

100

500

300

output:

Bresenham’s Line drawing algorithm

source code:

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
void main() {
int x,y,x1,y1,x2,y2,p,dx,dy;
int gd=DETECT,gm;
initgraph(&gd,&gm,"C:\\TurboC3\\BGI");

scanf("%d",&x1);

scanf("%d",&y1);

scanf("%d",&x2);

scanf("%d",&y2);
x=x1;
y=y1;
dx=x2-x1;
dy=y2-y1;
putpixel(x,y,2);
p=(2*dy-dx);
while(x<=x2) {
if(p<0) {
x=x+1;
p=p+2*dy;
}
else {
x=x+1;
y=y+1;
p=p+(2*dy)-(2*dx); }
putpixel(x,y,7); }
getch(); closegraph(); }

input:

10

10

50

30

output:

input:

100

100

500

300

output:

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