#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>


int	res=5;

void init(void)
{
	GLfloat mat_specular[]={1.0, 1.0, 1.0, 1.0};
	GLfloat mat_shininess[]= {50.0};
	GLfloat light_position[] = {1.0, 1.0, 1.0, 0.0 };

	glClearColor (0.0, 0.0, 0.0, 0.0);
	glShadeModel (GL_SMOOTH);

	glMaterialfv (GL_FRONT, GL_SPECULAR, mat_specular);
	glMaterialfv (GL_FRONT, GL_SHININESS, mat_shininess);
	glLightfv (GL_LIGHT0, GL_POSITION, light_position);

	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
	glEnable(GL_DEPTH_TEST);
}

void display(void)
{
	glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glutSolidSphere (1.0, res, res);
	glFlush();
}

void reshape (int w, int h)
{
	glViewport (0, 0, (GLsizei) w, (GLsizei) h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
	switch(key) {
		case 'R':
			res=res+1;
			if (res>50)
				res=50;
			break;
		case 'r':
			res=res-1;
			if (res<3)
				res=3;
			break;
		default:
			break;
	}
	glutPostRedisplay();
}

int	main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowSize (500,500);
	glutInitWindowPosition (100,100);
	glutCreateWindow(argv[0]);
	init();
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	glutKeyboardFunc(keyboard);
	glutMainLoop();
	return(0);
}