Write a program in C/C++ using OpenGL to show a ball is shrinking.

Try this code, run before writing.. Thanks




#include <windows.h> // for MS Windows #include <GL/glut.h> // GLUT, include glu.h and gl.h #include <math.h> // Global variable GLfloat angle = 0.0f; // Current rotational angle of the shapes /* Initialize OpenGL Graphics */ void initGL() { // Set "clearing" or background color glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Black and opaque } /* Called back when there is no other event to be handled */ void idle() { glutPostRedisplay(); // Post a re-paint request to activate display() } /* Handler for window-repaint event. Call back when the window first appears and whenever the window needs to be re-painted. */ void display() { glClear(GL_COLOR_BUFFER_BIT); // Clear the color buffer glMatrixMode(GL_MODELVIEW); // To operate on Model-View matrix glLoadIdentity(); // Reset the model-view matrix float radius = 0.80; glColor3ub(255, 0, 0); double twicePi = 2.0 * 3.142; int i, x, y; radius = radius + angle; x = 0, y = 0; glPushMatrix(); // Save model-view matrix setting glBegin(GL_TRIANGLE_FAN); //BEGIN CIRCLE glVertex2f(x, y); // center of circle for (i = 0; i <= 200; i++) { glVertex2f( (x - (radius * cos(i * twicePi / 200))), (y - (radius * sin(i * twicePi / 200))) ); } glEnd(); glPopMatrix(); // Restore the model-view matrix glutSwapBuffers(); // Double buffered - swap the front and back buffers angle -= 0.0001f; } /* Handler for window re-size event. Called back when the window first appears and whenever the window is re-sized with its new width and height */ void reshape(GLsizei width, GLsizei height) { // GLsizei for non-negative integer // Compute aspect ratio of the new window if (height == 0) height = 1; // To prevent divide by 0 GLfloat aspect = (GLfloat)width / (GLfloat)height; // Set the viewport to cover the new window glViewport(0, 0, width, height); // Set the aspect ratio of the clipping area to match the viewport glMatrixMode(GL_PROJECTION); // To operate on the Projection matrix glLoadIdentity(); if (width >= height) { // aspect >= 1, set the height from -1 to 1, with larger width gluOrtho2D(-1.0 * aspect, 1.0 * aspect, -1.0, 1.0); } else { // aspect < 1, set the width to -1 to 1, with larger height gluOrtho2D(-1.0, 1.0, -1.0 / aspect, 1.0 / aspect); } } /* Main function: GLUT runs as a console application starting at main() */ int main(int argc, char** argv) { glutInit(&argc, argv); // Initialize GLUT glutInitDisplayMode(GLUT_DOUBLE); // Enable double buffered mode glutInitWindowSize(840, 680); // Set the window's initial width & height - non-square glutInitWindowPosition(50, 50); // Position the window's initial top-left corner glutCreateWindow("Animation via Idle Function"); // Create window with the given title glutDisplayFunc(display); // Register callback handler for window re-paint event glutReshapeFunc(reshape); // Register callback handler for window re-size event glutIdleFunc(idle); // Register callback handler if no other event initGL(); // Our own OpenGL initialization glutMainLoop(); // Enter the infinite event-processing loop return 0; }