7. Graphics Program to display Circle.

Graphics Program to display Circle.

#include <GL/gl.h>

#include <GL/glut.h>

#include <math.h>

#include <stdio.h>

#include <stdlib.h>

#define window_width 1080

#define window_height 720

void drawFilledSun() {

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glLoadIdentity();

glTranslatef(0,0,-10);

int i,x,y;

double radius=0.30;

glColor3ub(0,0,255);

double twicepi=2.0*3.142;

x=0,y=0;

glBegin(GL_TRIANGLE_FAN);

glVertex2f(x,y);

for(i=0;i<=20;i++)

{

glVertex2f((x+(radius*cos(i*twicepi/20))),

                                                           

 (y+(radius*sin(i*twicepi/20))));

}

glEnd();

}

void drawCircle(float cx,float cy,float r,int num_segments) {

glBegin(GL_LINE_LOOP);

for(int ii=0;ii<num_segments;ii++) {

float theta=2.0f*3.1415926f*float(ii)/float(num_segments);

float x=r*cos(theta);

float y=r*sin(theta);

glVertex2f(x+cx,y+cy);

}

glEnd(); }

void main_loop_function()

 {

int c;

drawFilledSun();

drawCircle(0,0,0.5,100);

drawCircle(0,0,0.7,100);

drawCircle(0,0,0.9,100);

drawCircle(0,0,1.1,100);

drawCircle(0,0,1.3,100);

drawCircle(0,0,1.5,100);

drawCircle(0,0,1.7,100);

drawCircle(0,0,1.9,100);

drawCircle(0,0,2.1,100);

drawCircle(0,0,2.3,100);

drawCircle(0,0,2.5,100);

drawCircle(0,0,2.7,100);

drawCircle(0,0,2.9,100);

drawCircle(0,0,3.1,100);

drawCircle(0,0,3.3,100);

drawCircle(0,0,3.5,100);

drawCircle(0,0,3.7,100);

drawCircle(0,0,3.9,100);

drawCircle(0,0,4.1,100);

glutSwapBuffers();

c=getchar();

}

void GL_Setup(int width, int height) {

glViewport(0,0,width,height);

glMatrixMode(GL_PROJECTION);

glEnable(GL_DEPTH_TEST);

gluPerspective(45,(float)width/height,0.1,100);

glMatrixMode(GL_MODELVIEW);

}

int main(int argc, char** argv) {

glutInit(&argc, argv);

glutInitWindowSize(window_width, window_height);

glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE);

glutCreateWindow("GLUT Example!!");

glutIdleFunc(main_loop_function);

GL_Setup(window_width, window_height);

glutMainLoop(); }