C Program to find the points and draw lines using DDA algorithm | C Programming

C Program to find the points using DDA algorithm

Algorithm:-

Suppose at step i, the pixels is (x_i,y_i)

The line of equation for step i
              y_i=mx_i+b......................equation 1

Next value will be
              y_i+1=m_xi+1+b.................equation 2
              m =
             

              y_i+1-y_i=∆y.......................equation 3
              y_i+1-x_i=∆x......................equation 4
              y_i+1=y_i+∆y
              ∆y=m∆x
              y_i+1=y_i+m∆x
              ∆x=∆y/m
              x_i+1=x_i+∆x
              x_i+1=x_i+∆y/m

Case1: When |M|<1 assume="" sub="" that="" then="" x="">1
<1 assume="" sub="" that="" then="" x="">

              x= x₁,y=y₁ set ∆x=1
              y_i+1=y_1+m,     x=x+1
              Until x = x₂

Case2: When |M|<1 assume="" sub="" that="" then="" y="">1
<1 assume="" sub="" that="" then="" y="">

              x= x₁,y=y₁ set ∆y=1
              x_i+1=,     y=y+1
              

              Until y → y₂

#include<stdio.h>
#include<math.h>
int main()
{
int x1,x2,y1,y2;
float x,y;
int i=1,roundx,roundy,step;
float dx,dy,xinc,yinc,xnew,ynew;
printf("Enter the end points first\n");
scanf("%d%d",&x1,&y1);
printf("Enter the end points second\n");
scanf("%d%d",&x2,&y2);
printf("step\txold\tyold\txnew\tynew\tround(x),round(y)");
dx=(x2-x1);
dy=y2-y1;
if(abs(dx)>abs(dy))
{
step=abs(dx);
}
else
{
step=abs(dy);
}
x=x1;
y=y1;
xinc=dx/step;
yinc=dy/step;

xnew=(x+xinc);
ynew=(y+yinc);
roundx=roundl(xnew);
roundy=roundl(ynew); 
printf("\n%d\t%.2f\t%.2f\t%.2f\t%.2f\t(%d,%d)",i,x,y,xnew,ynew,roundx,roundy);
do
{
i++;
x=xnew;
y=ynew;
xnew=(x+xinc);
ynew=(y+yinc);
roundx=roundf(xnew);
roundy=roundf(ynew);
printf("\n%d\t%.2f\t%.2f\t%.2f\t%.2f\t(%d,%d)",i,x,y,xnew,ynew,roundx,roundy);
}
while(i<step);
}

C Programming Languages | C Program to draw lines using DDA algorithm

#include<stdio.h>
#include<math.h>
#include<graphics.h>
int main()
{
int gd=DETECT,gm;
initgraph(&gd,&gm,"");
int x1,x2,y1,y2;
float x,y;
int i=1,roundx,roundy,step;
float dx,dy,xinc,yinc,xnew,ynew;
printf("Enter the end points first\n");
scanf("%d%d",&x1,&y1);
printf("Enter the end points second\n");
scanf("%d%d",&x2,&y2);
dx=(x2-x1);
dy=y2-y1;
if(abs(dx)>abs(dy))
{
step=abs(dx);
}
else
{
step=abs(dy);
}
x=x1;
y=y1;
xinc=dx/step;
yinc=dy/step;
xnew=(x+xinc);
ynew=(y+yinc);
roundx=roundl(xnew);
roundy=roundl(ynew); 
putpixel(roundx,roundy,RED); 
do
{
i++;
x=xnew;
y=ynew;
xnew=(x+xinc);
ynew=(y+yinc);
roundx=roundf(xnew);
roundy=roundf(ynew);
putpixel(roundx,roundy,RED);
}
while(i<step);
getch();
closegraph;
}