program to show movement of circle along a line

#include<iostream.h>
#include<conio.h>
#include<graphics.h>
#include<math.h>
#include<dos.h>
// function for drawing circle of radius r having centre at m,n
void draw(int m,int n,int r)
{int x,y,p;
x=0;
y=r;
putpixel(m+y,n+x,1);
putpixel(m-y,n+x,1);
putpixel(m+x,n+y,1);
putpixel(m+x,n-y,1);
p=3-(2*r);
while(y>x)
{  if (p<0)
   p=(p+(4*x)+6);
   else
   { y=y-1;
     p=p+((4*(x-y)+10));
   }
   x++;
   putpixel(m+x,n+y,1);
   putpixel(m+x,n-y,1);
   putpixel(m-x,n-y,1);
   putpixel(m-x,n+y,1);
   putpixel(m-y,n-x,1);
   putpixel(m-y,n+x,1);
   putpixel(m+y,n+x,1);
   putpixel(m+y,n-x,1);
}
}

  void main()
     { int dx,dy,s1,s2,x1,x2,y1,y2,x,y,temp,e,i,c,r;
       cout<<"Enter the radius ";
       cin>>r;
      cout<<"enter the end points of line to move the circle along ( x1 x2 y1 y2 )\n";
      cin>>x1>>y1>>x2>>y2;
      int gdriver=DETECT,gmode;
      initgraph(&gdriver,&gmode,"");
      x=x1;y=y1;
      dx=abs(x2-x1);dy=abs(y2-y1);
      if(x2>x1)
    s1=1;
    else s1=-1;
      if(y2>y1)
      s2=1;
      else s2=-1;
  if(dy>dx)
  { temp=dx;
  dx=dy;
  dy=temp;
  c=1;
  }
  else c=0;
  e=2*dy-dx;
  for(i=1;i<=dx;i++)
  {  delay(40);
      clrscr();
      // calling function draw the circle
      draw(x,y,r);
      line(x1,y1,x,y);
    while(e>0)
     { if(c==1)
    { x+=s1;}
       else y=y+s2;
    e-=2*dx;
     }
    if(c==1)
     y+=s2;
    else
     x=x+s1;
  e+=2*dy;
  }
  getch();
}

implementation of concept of rotation in computer graphics

 #include<iostream.h>
#include<conio.h>
#include<graphics.h>
#include<math.h>
double object[3][3],translate[3][3],output[3][3], rotate[3][3],output2[3][3],output3[3][3];
int n;
void input(int n)
{for(int i=0;i<n;i++)
     {cout<<"\nenter x and y for cordinate #"<<i+1<<endl;
      cin>>object[i][0]>>object[i][1];
     }
}
void matmulti(double a[10][3],double b[3][3],double c[10][3])
{for(int i=0;i<3;i++)
  for(int j=0;j<3;j++)
   for(int k=0;k<3;k++)
       c[i][j]+=a[i][k]*b[k][j];
}

void display(double a[10][3],int n)
{ for(int i=0;i<n-1;i++)
      line(a[i][0],a[i][1],a[i+1][0],a[i+1][1]);
       line(a[0][0],a[0][1],a[n-1][0],a[n-1][1]);
}


void main()
{int i,j,ch,gd=DETECT,gm;
double theta;
translate[0][0]=1;
translate[1][1]=1;
translate[2][2]=1;
object[0][2]=1;
object[1][2]=1;
object[2][2]=1;


 cout<<"\n 1.rotate a line";
 cout<<"\n 2.rotate a triangle";
 cout<<"\n enter your choice : ";
 cin>>ch;
 if(ch==1)
   n=2;
 if(ch==2)
   n=3;
 input(n);
 initgraph(&gd,&gm,"");
 display(object,n);
 getch();
 closegraph();
 cout<<"\nenter the fix points tx and ty\n";
 cin>>translate[2][0]>>translate[2][1];
 cout<<"\nenter the angle to rotate";
 cin>>theta;theta=-theta;
 theta=(3.14)*theta/180;
 rotate[0][0]=cos(theta);
 rotate[0][1]=sin(theta);
 rotate[1][0]=-sin(theta);
 rotate[1][1]=cos(theta);
 rotate[2][2]=1;

 translate[2][0]=(-translate[2][0]);
 translate[2][1]=(-translate[2][1]);
 matmulti(translate,rotate,output);
 translate[2][0]=(-translate[2][0]);
 translate[2][1]=(-translate[2][1]);
 matmulti(output,translate,output2);
 matmulti(object,output2,output3);

  initgraph(&gd,&gm,"");
 display(object,n);
 setcolor(12);
 display(output3,n);
 getch();

}

implementation of concept of translation in computer graphics

Program in c for 2-D Translation of line and Triangle

#include<iostream.h>
#include<conio.h>
#include<graphics.h>
int object[3][3],translate[3][3],output[3][3],n;
void input(int n)
{for(int i=0;i<n;i++)
     {cout<<"\nenter x and y for cordinate #"<<i+1<<endl;
      cin>>object[i][0]>>object[i][1];
     }
}    
void matmulti(int a[10][3],int b[3][3],int c[10][3])
{for(int i=0;i<3;i++)
  for(int j=0;j<3;j++)
   for(int k=0;k<3;k++)
       c[i][j]+=a[i][k]*b[k][j];
}

void display(int a[10][3],int n)
{ for(int i=0;i<n-1;i++)
      line(a[i][0],a[i][1],a[i+1][0],a[i+1][1]);
       line(a[0][0],a[0][1],a[n-1][0],a[n-1][1]);
}     
     

void main()
{int i,j,ch,gd=DETECT,gm;
translate[0][0]=1;
translate[1][1]=1;
translate[2][2]=1;
object[0][2]=1;
object[1][2]=1;
object[2][2]=1;


 cout<<"\n 1.translate a line";
 cout<<"\n 2.translate a triangle";
 cout<<"\n enter your choice : ";
 cin>>ch;
 if(ch==1)
   n=2;
 if(ch==2)
   n=3;
 input(n);
 initgraph(&gd,&gm,"");
 display(object,n);
 getch();
 closegraph();
 cout<<"\nenter the translation factors tx and ty\n";
 cin>>translate[2][0]>>translate[2][1];
 matmulti(object,translate,output);
  initgraph(&gd,&gm,"");
 display(object,n);
 setcolor(12);
 display(output,n);
 getch();

}

Implementation of Midpoint Circle Algorithm

 The Algorithm

function line(x0, y0, x1, y1)
   dx := abs(x1-x0)
   dy := abs(y1-y0) 
   if x0 < x1 then sx := 1 else sx := -1
   if y0 < y1 then sy := 1 else sy := -1
   err := dx-dy
 
   loop
     setPixel(x0,y0)
     if x0 = x1 and y0 = y1 exit loop
     e2 := 2*err
     if e2 > -dy then 
       err := err - dy
       x0 := x0 + sx
     end if
     if e2 <  dx then 
       err := err + dx
       y0 := y0 + sy 
     end if
   end loop

 The Program 

 #include<iostream.h>
     #include<conio.h>
     #include<graphics.h>
     #include<math.h>
     #include<dos.h>
     void main()
     { int dx,dy,s1,s2,x1,x2,y1,y2,x,y,temp,e,i,c;
      cout<<"enter the coordinates of the line in the form x1 x2 y1 y2\n";
      cin>>x1>>y1>>x2>>y2;
      int gdriver=DETECT,gmode;
      initgraph(&gdriver,&gmode,"");
      x=x1;y=y1;
      dx=abs(x2-x1);
      dy=abs(y2-y1);
      if(x2>x1)
 s1=1;
 else s1=-1;
      if(y2>y1)
      s2=1;
      else s2=-1;
  if(dy>dx)
  { temp=dx;
  dx=dy;
  dy=temp;
  c=1;
  }
  else c=0;

  e=2*dy-dx;
  for(i=1;i<=dx;i++)
  {  delay(40);
   putpixel(x,y,10);
    while(e>0)
     { if(c==1)
 { x+=s1;}
       else y=y+s2;
 e-=2*dx;
     }
    if(c==1)
     y+=s2;
    else
     x=x+s1;
  e+=2*dy;
  }
  getch();
}

Implementation of DDA Line Drawing Algorithm

#include<iostream.h>

#include<conio.h>

#include<graphics.h>

#include<math.h>

void main()

{

clrscr();

float x,y;int x1,x2,y1,y2,dx,dy,l,i=0;

cout<<"Enter the coordinates in the form of x1,y1,x2,y2";

cin>>x1>>y1>>x2>>y2;

int gdriver=DETECT,gmode;

initgraph(&gdriver,&gmode,"");

if(abs(x2-x1)>abs(y2-y1))

l=abs(x2-x1);

else

l=abs(y2-y1);

dx=(x2-x1)/l;

dy=(y2-y1)/l;

x=x+0.5;

y=y+0.5;

while(i<=l)

{

putpixel(int(x),int(y),9);

x=x+dx;

y=y+dy;

i++;

}

getch();

}

Implementation of Bresenham's Algorithm For Line Drawing

 The Algorithm

function line(x0, y0, x1, y1)
   dx := abs(x1-x0)
   dy := abs(y1-y0) 
   if x0 < x1 then sx := 1 else sx := -1
   if y0 < y1 then sy := 1 else sy := -1
   err := dx-dy
 
   loop
     setPixel(x0,y0)
     if x0 = x1 and y0 = y1 exit loop
     e2 := 2*err
     if e2 > -dy then 
       err := err - dy
       x0 := x0 + sx
     end if
     if e2 <  dx then 
       err := err + dx
       y0 := y0 + sy 
     end if
   end loop

 The Program 

 #include<iostream.h>
     #include<conio.h>
     #include<graphics.h>
     #include<math.h>
     #include<dos.h>
     void main()
     { int dx,dy,s1,s2,x1,x2,y1,y2,x,y,temp,e,i,c;
      cout<<"enter the coordinates of the line in the form x1 x2 y1 y2\n";
      cin>>x1>>y1>>x2>>y2;
      int gdriver=DETECT,gmode;
      initgraph(&gdriver,&gmode,"");
      x=x1;y=y1;
      dx=abs(x2-x1);
      dy=abs(y2-y1);
      if(x2>x1)
 s1=1;
 else s1=-1;
      if(y2>y1)
      s2=1;
      else s2=-1;
  if(dy>dx)
  { temp=dx;
  dx=dy;
  dy=temp;
  c=1;
  }
  else c=0;

  e=2*dy-dx;
  for(i=1;i<=dx;i++)
  {  delay(40);
   putpixel(x,y,10);
    while(e>0)
     { if(c==1)
 { x+=s1;}
       else y=y+s2;
 e-=2*dx;
     }
    if(c==1)
     y+=s2;
    else
     x=x+s1;
  e+=2*dy;
  }
  getch();
}