Tuesday, 30 December 2014

C program to draw Koch Curve using recursion


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

void koch(int x1, int y1, int x2, int y2, int it)
{
float angle = 60*M_PI/180;
int x3 = (2*x1+x2)/3;
int y3 = (2*y1+y2)/3;

int x4 = (x1+2*x2)/3;
int y4 = (y1+2*y2)/3;

int x = x3 + (x4-x3)*cos(angle)+(y4-y3)*sin(angle);
int y = y3 - (x4-x3)*sin(angle)+(y4-y3)*cos(angle);

if(it > 0)
{
koch(x1, y1, x3, y3, it-1);
koch(x3, y3, x, y, it-1);
koch(x, y, x4, y4, it-1);
koch(x4, y4, x2, y2, it-1);
}
else
{

line(x1, y1, x3, y3);
line(x3, y3, x, y);
line(x, y, x4, y4);
line(x4, y4, x2, y2);
}
}

int main(void)
{
int gd = DETECT, gm;
initgraph(&gd, &gm, "C:\\TC\\BGI");
int x1 = 100, y1 = 100, x2 = 400, y2 = 400;
koch(x1, y1, x2, y2, 4);
getch();
return 0;
}
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16 comments:

  1. Unknown17 September 2016 at 08:27

    there is an error in this program.
    int x1=100,y1=100,x2=400,y2=400
    Error:Declaration is not allowed here.

    ReplyDelete
    Replies
    1. Unknown18 September 2016 at 05:15

      just put initgraph below the declarations

      Delete
    2. Unknown24 March 2020 at 11:01

      save file as .cpp

      Delete
    3. sapwood19 November 2020 at 04:02

      just remove that void function from the int main(void) and compile the program then it will not show the error ^ remove it.

      Delete
  2. Unknown3 April 2017 at 23:24

    exucted command teell me

    ReplyDelete
  3. Unknown12 April 2017 at 04:01

    #include<iostream.h>

    #include<conio.h>

    #include<graphics.h>

    #include<math.h>

    /*struct node

    {

    float x;

    float y;

    };*/

    int dx;

    void koch(float x1,float y1,float x2,float y2)

    {

    float x,px,py;

    x=(x2-x1);

    if(x<=dx) return;

    if(y1==y2)

    {

    line(x1,y1,x1+x/3,y1);

    line(x1+2*x/3,y2,x2,y2);

    px=(x2-x1)/2+x1;

    py=y1-((x/6)*sqrt(3));

    line(x1+x/3,y1,px,py);

    line(px,py,x1+2*x/3,y2);

    setcolor(BLACK);

    line(x1+x/3,y1,x1+2*x/3,y1);

    setcolor(WHITE);

    koch(x1,y1,x1+x/3,y1);

    koch(x1+2*x/3,y2,x2,y2);

    koch(x1+x/3,y1,px,py);

    koch(px,py,x1+2*x/3,y2);

    }

    else

    {

    float ax,ay,bx,by,cx,cy;

    if(y1>y2)

    {

    setcolor(BLACK);

    line(x1,y1,x2,y2);

    setcolor(WHITE);

    ax=x1+x/3;

    ay=y1-(y1- y2)/3;

    cx=x1+2*x/3;

    cy=y1-2*(y1- y2)/3;

    bx=cx-2*x/3;

    by=cy;

    line(x1,y1,ax,ay);

    line(ax,ay,bx,by);

    line(bx,by,cx,cy);

    line(cx,cy,x2,y2);

    koch(x1,y1,ax,ay);

    koch(bx,by,ax,ay);

    koch(bx,by,cx,cy);

    koch(cx,cy,x2,y2);

    }

    if(y1<y2)

    {

    setcolor(BLACK);

    line(x1,y1,x2,y2);

    setcolor(WHITE);

    ax=x1+x/3;

    ay=y1+(y2-y1)/3;

    cx=x1+2*x/3;

    cy=y1+2*(y2-y1)/3;

    bx=ax+2*x/3;

    by=ay;

    line(x1,y1,ax,ay);

    line(ax,ay,bx,by);

    line(bx,by,cx,cy);

    line(cx,cy,x2,y2);

    koch(x1,y1,ax,ay);

    koch(ax,ay,bx,by);

    koch(cx,cy,bx,by);

    koch(cx,cy,x2,y2);

    }

    }

    }

    int main()

    {

    int gd=DETECT,gm;

    initgraph(&gd,&gm,"c:\\turboc3\\bgi");

    float x1,y1,x2,y2;

    cout<<"enter end points of line(x,y)";

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

    cout<<"enter minimum spacing";

    cin>>dx;

    koch(x1,y1,x2,y2);

    getch();

    return 0;

    }

    ReplyDelete
  4. Unknown19 April 2017 at 05:07

    What is value of variable it....why we use that variable

    ReplyDelete
  5. Unknown19 April 2017 at 05:08

    What is value of variable it....why we use that variable

    ReplyDelete
    Replies
    1. Sumedh Sen21 April 2017 at 07:38

      i gues thats the degree of the koch curve.

      Delete
  6. Sumedh Sen21 April 2017 at 07:39

    how did u derive the formula of the points in method koch()?

    ReplyDelete
  7. Anonymous26 December 2017 at 00:02

    hey ,
    I have also tried a C++ program for Koch curve and written it on my blog ,
    check it out at link below :
    http://computerstudentworld...
    and give me suggestions if any,
    Thank you!

    ReplyDelete
  8. Unknown15 April 2018 at 06:11

    ~~Insted of Taking the taking SIN & Cos values I take direct sin(60)=0.866 and cos(60)=0.5
    #include
    #include
    #include
    #include
    using namespace std;
    #define SIN 0.866

    void koch(int x1,int y1,int x2,int y2,int m)
    {
    int xx,yy,x[5],y[5],lx,ly,offx=50,offy=300;

    lx=(x2-x1)/3;
    ly=(y2-y1)/3;
    x[0]=x1;
    y[0]=y1;
    x[4]=x2;
    y[4]=y2;
    x[1]=x[0]+lx;
    y[1]=y[0]+ly;
    x[3]=x[0]+2*lx;
    y[3]=y[0]+2*ly;
    xx=x[3]-x[1];
    yy=y[3]-y[1];
    x[2]=xx*(0.5)+yy*(SIN);
    y[2]=-xx*(SIN)+yy*(0.5);
    x[2]=x[2]+x[1];
    y[2]=y[2]+y[1];
    if(m>0)
    {
    koch(x[0],y[0],x[1],y[1],m-1);
    koch(x[1],y[1],x[2],y[2],m-1);
    koch(x[2],y[2],x[3],y[3],m-1);
    koch(x[3],y[3],x[4],y[4],m-1);
    }
    else
    {
    line(offx+x[0],offy+y[0],offx+x[1],offy+y[1]);
    line(offx+x[1],offy+y[1],offx+x[2],offy+y[2]);
    line(offx+x[2],offy+y[2],offx+x[3],offy+y[3]);
    line(offx+x[3],offy+y[3],offx+x[4],offy+y[4]);
    }
    }
    int main()
    {
    int n,gd,gm;
    int x1=0,x2=550,y1=0,y2=0;
    cout<<"\nenter the level of the curve generation :";
    cin>>n;
    detectgraph(&gd,&gm);
    initgraph(&gd,&gm,NULL);
    koch(x1,y1,x2,y2,n);

    getch();
    closegraph();
    return 0;
    }

    ReplyDelete
  9. Unknown6 December 2018 at 01:15

    Very helpful.

    ReplyDelete
  10. Unknown3 August 2019 at 09:35

    Best easy code for koch curve

    ReplyDelete
  11. sapwood19 November 2020 at 04:29

    Thanks for the code :).

    ReplyDelete

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