circle_new.cpp

#include <iostream>
#include <GL/gl.h>
#include <GL/glut.h>
#include <math.h>


#define PI 3.14159265

using namespace std;
int a,b,r;


float roundVal(float d)
{
    return floor(d + 0.5);
}

void displayCircle(void)
{
    glClear (GL_COLOR_BUFFER_BIT);
    glColor3ub(0, 0, 0);
    glPointSize(2.0);
    int x=0,y=0;



  double result,param;
  param = 90.0;

  while(param>45.00){
    double cosVal= cos (param*PI/180);
    double sinVal= sin (param*PI/180);

    y=roundVal(r*sinVal);
    x=roundVal(r*cosVal);

    param--;

        glBegin(GL_POINTS);
        glVertex2i(x+a,y+b);
        glVertex2i(y+a,x+b);
        glVertex2i(y+a,-x+b);
        glVertex2i(x+a,-y+b);
        glVertex2i(-x+a,-y+b);
        glVertex2i(-y+a,-x+b);
        glVertex2i(-y+a,x+b);
        glVertex2i(-x+a,y+b);
        glEnd();


    glFlush ();

  }


}



void myInit(void)
{
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glColor3ub(0, 0, 0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluOrtho2D(-400.0, 400.0, -400.0, 400.0);
}

main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize (400, 400);
    glutInitWindowPosition (100, 150);
    glutCreateWindow ("Circle");
    cout<<"Radius?"<<endl;
    cin>>r;
    std::cout<<"Input  values circle a,b:";
    std::cin>>a;
    std::cin>>b;
    myInit();
    glutDisplayFunc(displayCircle);

    glutMainLoop();
}

line_intercept.cpp

#include <iostream>
#include <stdlib.h>
#include <math.h>
#include<GL/gl.h>
#include <GL/glut.h>

#define PI 3.14159265

using namespace std;

double pointX1, pointY1, pointX2, pointY2;

float roundVal(float d)
{
    return floor(d + 0.5);
}
void Line()
{
    double dx=(pointX2-pointX1);
    double dy=(pointY2-pointY1);
    double m = dy/dx;

    double theta = atan (m) * 180 / PI;

    double x,y,xEnd,yEnd;

    cout<<theta<<endl;



    glClear(GL_COLOR_BUFFER_BIT);
    glPointSize(1.0);
    glBegin(GL_POINTS);

    glVertex2d(x,y);

    double c = y - m*x;


    if(theta >= 45 && theta <= -45){


        if(dy > 0){
            x=pointX1;
            y=pointY1;
            yEnd = pointY2;

        }
        else {
            x=pointX2;
            y=pointY2;
            yEnd = pointY1;
        }


        while(y < yEnd)
        {
            glVertex2d(roundVal(x), roundVal(y));
            y++;
            x = (y-c)/m;
            c = y - m*x;
        }
    }
    else {
        if(dx > 0){
            x=pointX1;
            y=pointY1;
            xEnd = pointX2;

        }
        else {
            x=pointX2;
            y=pointY2;
            xEnd = pointX1;
        }


        while(x < xEnd)
        {
            glVertex2d(roundVal(x), roundVal(y));
            x++;
            y = m*x + c;
             c = y - m*x;
        }
    }




    glEnd();

    glFlush();
}

void myInit()
{
    glClearColor(1,1,1,0);
    glColor3f(0.0,0.0,0.0);
    gluOrtho2D(0, 600, 0, 600);
}
void inputPoints()
{
    cout<<"Enter start points: "<<endl;
    cin>>pointX1;
    cin>>pointY1;
    pointY1 = pointY1+1;
    cout<<"Enter end points:"<<endl;
    cin>>pointX2;
    pointX2 = pointX2+1;
    cin>>pointY2;
}
int main(int argc, char **argv)
{


    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);

    glutInitWindowPosition(100,30);
    glutInitWindowSize(600,600);
    glutCreateWindow("Line Algorithms ");
    myInit();
    while(true)
    {


            inputPoints();
            glutDisplayFunc(Line);
            glutMainLoop();



    }


}