Circle (8 quad) - Computer Graphics

circle.cpp

#include<iostream>
#include <GL/gl.h>
#include <GL/glut.h>
using namespace std;

int R;
int h, k;
int startX, startY;

void drawAxes(){

    glBegin(GL_LINES);
    glVertex2i(0, 300);
    glVertex2i(0, -300);
    glEnd();

    glBegin(GL_LINES);
    glVertex2i(-300, 0);
    glVertex2i(300, 0);
    glEnd();

}


//8th quad
void draw8thQuad(){
    int x1 = R + k;
    int y1 = 0 + h;
    int h = 1 - R;

    while(x1 > y1){
           //print points
        glBegin(GL_POINTS);
        glVertex2i(x1, -y1);
        glEnd();
        if(h <= 0) {
            //go e
            y1 = y1 + 1;
            //update h
            h = h + (2* y1) + 3;
        } else {
            //go se
            y1 = y1 + 1;
            x1 = x1 - 1;
            //update h
            h = h + 2 * (y1 - x1) + 5;
        }
    }

}

//6th quad
void draw6thQuad(){
     int x1 = 0 + h;
    int y1 = R + k;
    int h = 1 - R;
    //startX = x1;
    //startY = y1;

    while(y1 > x1){
        //print points
        glBegin(GL_POINTS);
        glVertex2i(-x1, -y1);
        glEnd();
        if(h <= 0) {
            //go e
            x1 = x1 + 1;
            //update h
            h = h + (2* x1) + 3;
        } else {
            //go se
            x1 = x1 + 1;
            y1 = y1 - 1;
            //update h
            h = h + 2 * (x1 - y1) + 5;
        }
    }
}

//5tjh quad
void draw5thQuad(){
    int x1 = R + k;
    int y1 = 0 + h;
    int h = 1 - R;

    while(x1 > y1){
           //print points
        glBegin(GL_POINTS);
        glVertex2i(-x1, -y1);
        glEnd();
        if(h <= 0) {
            //go e
            y1 = y1 + 1;
            //update h
            h = h + (2* y1) + 3;
        } else {
            //go se
            y1 = y1 + 1;
            x1 = x1 - 1;
            //update h
            h = h + 2 * (y1 - x1) + 5;
        }
    }
}


//4th quad
void draw4thQuad(){
    int x1 = R + k;
    int y1 = 0 + h;
    int h = 1 - R;

    while(x1 > y1){
           //print points
        glBegin(GL_POINTS);
        glVertex2i(-x1, y1);
        glEnd();
        if(h <= 0) {
            //go e
            y1 = y1 + 1;
            //update h
            h = h + (2* y1) + 3;
        } else {
            //go se
            y1 = y1 + 1;
            x1 = x1 - 1;
            //update h
            h = h + 2 * (y1 - x1) + 5;
        }
    }

}


// 3rd quad
void draw3rdQuad(){
    int x1 = 0 + h;
    int y1 = R + k;
    int h = 1 - R;
    //startX = x1;
    //startY = y1;

    while(y1 > x1){
        //print points
        glBegin(GL_POINTS);
        glVertex2i(-x1,y1);
        glEnd();
        if(h <= 0) {
            //go e
            x1 = x1 + 1;
            //update h
            h = h + (2* x1) + 3;
        } else {
            //go se
            x1 = x1 + 1;
            y1 = y1 - 1;
            //update h
            h = h + 2 * (x1 - y1) + 5;
        }
    }
}

//7th quad
void draw7thQuad(){
    int x1 = 0 + h;
    int y1 = R + k;
    int h = 1 - R;
    //startX = x1;
    //startY = y1;

    while(y1 > x1){
        //print points
        glBegin(GL_POINTS);
        glVertex2i(x1,-y1);
        glEnd();
        if(h <= 0) {
            //go e
            x1 = x1 + 1;
            //update h
            h = h + (2* x1) + 3;
        } else {
            //go se
            x1 = x1 + 1;
            y1 = y1 - 1;
            //update h
            h = h + 2 * (x1 - y1) + 5;
        }
    }
}

//1st quadrant
void draw1stQuad(){
    int x1 = R + k;
    int y1 = 0 + h;
    int h = 1 - R;

    while(x1 > y1){
           //print points
        glBegin(GL_POINTS);
        glVertex2i(x1, y1);
        glEnd();
        if(h <= 0) {
            //go e
            y1 = y1 + 1;
            //update h
            h = h + (2* y1) + 3;
        } else {
            //go se
            y1 = y1 + 1;
            x1 = x1 - 1;
            //update h
            h = h + 2 * (y1 - x1) + 5;
        }
    }
}

// 2nd quadrant
void draw2ndQuad(){
    int x1 = 0 + h;
    int y1 = R + k;
    int h = 1 - R;
    //startX = x1;
    //startY = y1;

    while(y1 > x1){
        //print points
        glBegin(GL_POINTS);
        cout<<"x: "<<x1<<" y: "<<y1<<endl;
        glVertex2i(x1, y1);
        glEnd();
        if(h <= 0) {
            //go e
            x1 = x1 + 1;
            //update h
            h = h + (2* x1) + 3;
        } else {
            //go se
            x1 = x1 + 1;
            y1 = y1 - 1;
            //update h
            h = h + 2 * (x1 - y1) + 5;
        }
    }
}



void display(void)
{
/* clear all pixels */
glClear(GL_COLOR_BUFFER_BIT);

glColor3f(0.0, 1.0, 0.0);//(R,G,B)

    drawAxes();

    draw2ndQuad();
    draw1stQuad();
    draw7thQuad();
    draw3rdQuad();
    draw4thQuad();
    draw5thQuad();
    draw6thQuad();
    draw8thQuad();

glFlush();
}



void init(void)
{
/* select clearing (background) color */
glClearColor(0.0, 0.0, 0.0, 0.0);
/* initialize viewing values */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(-300, 300, -300, 300);
//glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}
/*
* Declare initial window size, position, and display mode
* (single buffer and RGBA). Open window with “hello”
* in its title bar. Call initialization routines.
* Register callback function to display graphics.
* Enter main loop and process events.
*/
int main(int argc, char** argv)
{
/*
R = 150;
h = 5;
k = 10;
*/

cout<<"R: ";
cin>>R;
cout<<endl;
cout<<"h: ";
cin>>h;
cout<<endl;
cout<<"k: ";
cin>>h;
cout<<endl;
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(300, 300);
glutInitWindowPosition(300, 100);
glutCreateWindow("Circle");
init();
glutDisplayFunc(display);
glutMainLoop();
return 0; /* ISO C requires main to return int. */
}