ball-around-circle.cpp

#include <GLUT/GLUT.h>
#include<OpenGL/OpenGL.h>

#include<iostream>
//#include<time>
#include<cstdlib>

#include <cmath>
#include <cstdio>

float x=3.0,y=0.0,angle=0.0,da=0.005;

void initRendering()
{
    glEnable(GL_DEPTH_TEST);
}

void reshape(int w,int h)
{
    glViewport(0,0,w,h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45,w/h,1,200);
}

void keyPressed(int key,int,int)
{
    if(key==GLUT_KEY_LEFT)
    {}
}
void drawBall1()
{
    glColor3f(0.0,1.0,1.0);
    glPushMatrix();
    glTranslatef(0.0,0.0,-5.0);
    glutSolidSphere(0.62,160,160);
    glPopMatrix();
}
void drawBall2()
{
    glColor3f(1.0,1.0,1.0);
    glPushMatrix();
    glTranslatef(x,y,-20.0);
    glutSolidSphere(0.5,20,20);
    glPopMatrix();
}

void update()
{
    angle+=da;
    if(angle>=6.28 || angle<=0)
    {
        da=-da;
    }
    x=3*sin(angle);
    y=3*cos(angle);
}
void display()
{
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    drawBall1();
    drawBall2();
    update();
    glutSwapBuffers();
}


int main(int argc,char **argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);
    glutInitWindowSize(600,600);
    glutCreateWindow("Rotating Ball Around Circle !");
    initRendering();
    glutDisplayFunc(display);
    glutIdleFunc(display);
    glutReshapeFunc(reshape);
    glutSpecialFunc(keyPressed);
    glutMainLoop();
    return(0);
}