Draw inscribed and Circumscribed circles in the triangle by using Bresenham circle and bresenham Line Alorithm

Program:

  #include<stdio.h> 
  #include<GL/glut.h> 
  #include<math.h> 
  int ww=1200,wh=800; 
  int xi,yi,xf,yf,r;
  float theta=2.0933;

 void putpixel(int x,int y) 
  { 
       glBegin(GL_POINTS); 
       glVertex2i(x,y); 
       glEnd(); 
       glFlush(); 
  } 
  double round(double n) 
  { 
       return (n>=0)?(int)(n+0.5):(int)(n-0.5); 
  } 
  void Bresenham_circle(int xc, int yc, int xr) 
  { 
        int x=0,y=xr;
        int d=3-2*y;
        while(x<=y){ 
        putpixel(x+xc, y+yc); 
        putpixel(xc+y, yc+x); 
        putpixel(xc-x, yc+y); 
        putpixel(xc-x, yc-y); 
        putpixel(xc-y, yc+x); 
        putpixel(xc-y, yc-x); 
        putpixel(xc+y, yc-x); 
        putpixel(xc+x, yc-y); 
            if(d<0) 
                 d=d+(4*x)+6; 
            else{ 
                 d=d+(4*(x-y))+10; 
                 y--; 
            } 
            x++; 
       } 
  } 

 void bresenhamAlg (int x0, int y0, int x1, int y1) 
  { 
  int dx = abs (x1 - x0); 
  int dy = abs (y1 - y0); 
  int x, y; 
  if (dx >= dy) 
  { 
   int d = 2*dy-dx; 
   int ds = 2*dy; 
   int dt = 2*(dy-dx); 
       if (x0 < x1)  
       { 
            x = x0; 
            y = y0; 
       } 
        else 
        {  
             x = x1; 
             y = y1; 
             x1 = x0; 
             y1 = y0; 
        } 
       putpixel (x, y); 
   while (x < x1) 
   { 
        if (d < 0) 
        d += ds; 
        else { 
             if (y < y1) { 
              y++; 
              d += dt; 
             }  
             else { 
              y--; 
              d += dt; 
             } 
            } 
   x++; 
        putpixel (x, y); 
       }  }
       else {  
             int d = 2*dx-dy; 
             int ds = 2*dx; 
             int dt = 2*(dx-dy); 
             if (y0 < y1) { 
             x = x0; 
             y = y0; 
             } 
             else {  
             x = x1; 
             y = y1; 
             y1 = y0; 
             x1 = x0; 
             } 
            putpixel (x, y);  
        while (y < y1) 
        { 
              if (d < 0) 
                 d += ds; 
              else { 
                      if (x > x1){ 
                      x--; 
                      d += dt; 
                 } else { 
                      x++; 
                      d += dt; 
                   } 
              } 
              y++;
              putpixel (x, y); 
        } 
       } 
  } 
 void triangle (int ix , int iy)
 {
    int x=ix, y=iy,x1,x2,y1,y2;
    x1=xi+(x-xi)*cos(theta)-(y-yi)*sin(theta);
    y1=yi-r/2;
    x2=xi+(x-xi)*cos(theta)+(y-yi)*sin(theta);
    y2=yi-r/2;;
    bresenhamAlg (x, y, x1, y1);
    bresenhamAlg (x, y, x2, y2);
    bresenhamAlg (x1, y1, x2, y2);
 }
 void display() 
  { 
        glClearColor(0.4,0.7,0.2,1.0); 
        glColor3f(0.5,0.3,0.0); 
        glClear(GL_COLOR_BUFFER_BIT); 
        glutSwapBuffers();
        Bresenham_circle(xi,yi,r);
        Bresenham_circle(xi,yi,r/2);
        triangle(xi,(yi+r));
        glFlush(); 
  } 
 

  void myinit() 
  { 
        glViewport(0,0,ww,wh); 
        glMatrixMode(GL_PROJECTION); 
        glLoadIdentity(); 
        gluOrtho2D(0.0,(GLdouble)ww,0.0,(GLdouble)wh); 
        glMatrixMode(GL_MODELVIEW); 
  } 
  int main(int argc,char** argv) 
  { 
    printf("enter centre of the circle");
    scanf("%d%d",&xi,&yi);
    printf("\nenter radius of circle");
    scanf("%d",&r);      
    glutInit(&argc,argv); 
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); 
    glutInitWindowSize(ww,wh); 
    glutCreateWindow("Bresenham-Circle"); 
    myinit();
    glutDisplayFunc(display); 
    glutMainLoop(); 
    return 0; 
  } 



Output:

Draw the pattern using BRESENHAM Line drawing algorithms using MOUSE in OpenGL

 Program:

#include <GL/glut.h> 
#include <math.h> 
int ww = 600, wh = 400; 
int first = 0; 
int xi, yi, xf, yf; 
void putPixel (int x, int y) 
{ 
   glBegin (GL_POINTS); 
   glVertex2i (x, y); 
   glEnd (); 
   glFlush ();
  } 
  void display() 
  { 
   glClearColor(0.4, 0.7, 0.5, 1.0); 
   glClear(GL_COLOR_BUFFER_BIT); 
   glFlush(); 
  } 
  void bresenhamAlg (int x0, int y0, int x1, int y1) 
  { 
  int dx = abs (x1 - x0); 
  int dy = abs (y1 - y0); 
  int x, y; 
  if (dx >= dy) 
  { 
   int d = 2*dy-dx; 
   int ds = 2*dy; 
   int dt = 2*(dy-dx); 
       if (x0 < x1)  
       { 
            x = x0; 
            y = y0; 
       } 
        else 
        {  
             x = x1; 
             y = y1; 
             x1 = x0; 
             y1 = y0; 
        } 
       putPixel (x, y); 
   while (x < x1) 
   { 
        if (d < 0) 
        d += ds; 
        else { 
             if (y < y1) { 
              y++; 
              d += dt; 
             }  
             else { 
              y--; 
              d += dt; 
             } 
            } 
   x++; 
        putPixel (x, y); 
       }  }
       else {  
             int d = 2*dx-dy; 
             int ds = 2*dx; 
             int dt = 2*(dx-dy); 
             if (y0 < y1) { 
             x = x0; 
             y = y0; 
             } 
             else {  
             x = x1; 
             y = y1; 
             y1 = y0; 
             x1 = x0; 
             } 
            putPixel (x, y);  
        while (y < y1) 
        { 
              if (d < 0) 
                 d += ds; 
              else { 
                      if (x > x1){ 
                      x--; 
                      d += dt; 
                 } else { 
                      x++; 
                      d += dt; 
                   } 
              } 
              y++; 
              putPixel (x, y); 
        } 
       } 
  } 
       void mouse(int btn, int state, int x, int y) 
       { 
        if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) 
        { 
        switch(first) 
        { 
        case 0: 
         xi = x; 
         yi = (wh-y); 
         first = 1; 
         break; 
        case 1: 
         xf = x; 
         yf = (wh-y); 
        
glColor3f(1.0,0.0,0.0);
    bresenhamAlg(xi,yi,xi,yf);
    bresenhamAlg(xi,yf,xf,yf);
    bresenhamAlg(xf,yf,xf,yi);
    bresenhamAlg(xf,yi,xi,yi);
 glColor3f(0.0,1.0,0.0);
    bresenhamAlg(xi,(yi+yf)/2,(xi+xf)/2,yf);
    bresenhamAlg((xi+xf)/2,yf,xf,(yi+yf)/2);
    bresenhamAlg(xf,(yi+yf)/2,(xi+xf)/2,yi);
    bresenhamAlg((xi+xf)/2,yi,xi,(yi+yf)/2);   
 glColor3f(0.0,0.0,1.0);
    bresenhamAlg((xi+(xi+xf)/2)/2,(yf+(yi+yf)/2)/2,(xf+(xi+xf)/2)/2,(yf+(yi+yf)/2)/2);
    bresenhamAlg((xf+(xi+xf)/2)/2,(yf+(yi+yf)/2)/2,(xf+(xi+xf)/2)/2,(yi+(yi+yf)/2)/2);
    bresenhamAlg((xf+(xi+xf)/2)/2,(yi+(yi+yf)/2)/2,(xi+(xi+xf)/2)/2, (yi+(yi+yf)/2)/2);
    bresenhamAlg((xi+(xi+xf)/2)/2, (yi+(yi+yf)/2)/2,(xi+(xi+xf)/2)/2,(yf+(yi+yf)/2)/2); 
         first = 0; 
         break;  
        } 
        } 
       } 
  void myinit() 
  {       
     glViewport(0,0,ww,wh); 
     glMatrixMode(GL_PROJECTION); 
     glLoadIdentity(); 
     gluOrtho2D(0.0,(GLdouble)ww,0.0,(GLdouble)wh); 
     glMatrixMode(GL_MODELVIEW); 
  } 
  int main(int argc, char** argv) 
  { 
     glutInit(&argc,argv); 
     glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); 
     glutInitWindowSize(ww,wh); 
     glutCreateWindow("Bresenham Line Algorithm With Mouse"); 
     glutDisplayFunc(display); 
     myinit(); 
     glutMouseFunc(mouse); 
     glutMainLoop(); 
     return 0; 
  } 

Output:

Draw the pattern using DDA Line drawing algorithm with KeyBoard in OpenGL

Program:
#include<stdio.h>
#include<GL/glut.h>
#include<math.h>
int xx1,xx2,yy1,yy2;
int sign(int x)
{
    if(x > 0) return 1;
    if(x < 0) return -1;
    return 0;
}
void drawline(int X1,int Y1, int X2,int Y2)  
{
    float x,y,dx,dy,length;
    int i;
    dx=abs(X2-X1);
    dy=abs(Y2-Y1);
    if(dx>=dy)
        length=dx;
    else
        length=dy;
    dx=(X2-X1)/length;
    dy=(Y2-Y1)/length;
    x=X1 + 0.5*sign(X1);
    y=Y1 + 0.5*sign(Y1);
    i=1;
    while(i<=length)
    {
   
                 glBegin(GL_POINTS);
             glVertex2i(x,y);
             glEnd();
                 glFlush();
        x=x+dx;
        y=y+dy;
        i=i+1;
    }
    glFlush();
}
  
void display(void)                            
{
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0,0.0,0.0);
    drawline(xx1,yy1,xx1,yy2);
    drawline(xx1,yy2,xx2,yy2);
    drawline(xx2,yy2,xx2,yy1);
    drawline(xx2,yy1,xx1,yy1);
     glColor3f(0.0,1.0,0.0);
    drawline(xx1,(yy1+yy2)/2,(xx1+xx2)/2,yy2);
    drawline((xx1+xx2)/2,yy2,xx2,(yy1+yy2)/2);
    drawline(xx2,(yy1+yy2)/2,(xx1+xx2)/2,yy1);
    drawline((xx1+xx2)/2,yy1,xx1,(yy1+yy2)/2);  
     glColor3f(0.0,0.0,1.0);
    drawline((xx1+(xx1+xx2)/2)/2,(yy2+(yy1+yy2)/2)/2,(xx2+(xx1+xx2)/2)/2,(yy2+(yy1+yy2)/2)/2);
    drawline((xx2+(xx1+xx2)/2)/2,(yy2+(yy1+yy2)/2)/2,(xx2+(xx1+xx2)/2)/2,(yy1+(yy1+yy2)/2)/2);
    drawline((xx2+(xx1+xx2)/2)/2,(yy1+(yy1+yy2)/2)/2,(xx1+(xx1+xx2)/2)/2, (yy1+(yy1+yy2)/2)/2);
    drawline((xx1+(xx1+xx2)/2)/2, (yy1+(yy1+yy2)/2)/2,(xx1+(xx1+xx2)/2)/2,(yy2+(yy1+yy2)/2)/2);  

}
void init(void)
{
       glViewport(0,0,640,480); 
       glMatrixMode(GL_PROJECTION); 
       glLoadIdentity(); 
       gluOrtho2D(0.0,640.0,0.0,480.0); 
       glMatrixMode(GL_MODELVIEW);    
}
int main(int argc,char** argv)
{
    printf("\n Enter vertex x1 ");
        scanf("%d",&xx1);
        printf("\n Enter vertex y1 ");
        scanf("%d",&yy1);
        printf("\n Enter vertex x2 ");
        scanf("%d",&xx2);
        printf("\n Enter vertex y2 ");
        scanf("%d",&yy2);
        glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(640,480);
    glutInitWindowPosition(0,0);
    glutCreateWindow("DDA Line");
    init();
    glClear(GL_COLOR_BUFFER_BIT);
    glutDisplayFunc(display);
    glFlush();
    glutMainLoop();
    return 0;
}
Output:

 

How to Install OpenGL in Ubuntu

Prerequisite : Internet Connection

To install OpenGL on system you need to install some basic packages. Open terminal and execute the following commands on terminal.
Step 1: sudo apt-get update 
             To update your basic packages
Step 2: sudo apt-get install build-essential
              For installing essential packages.
Step 3: sudo apt-get install freeglut3 freeglut3-dev
Step 4: sudo apt-get install binutils-gold
Step 5: sudo apt-get install g++ cmake
Step 6: sudo apt-get install mesa-common-dev mesa-utils
Step 7: sudo apt-get install libglew-dev libglew1.5-dev libglm-dev
Step 8: glxinfo | grep OpenGL

Now you are ready to compile your program!
● Write your program using any editor and save.
● Open the terminal for the specified folder and then run with:
gcc MyProg.c -lGL -lGLU -lglut (for C program)
g++ MyProg.cpp -lGL -lGLU -lglut (for C++ program)
./a.out
● Once all this installation process is done, you don't need to follow this process again and again. Just
compile and execute the program.