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

float spin = 0.0;

void display(void) {	/* OpenGL Rendering Function */
	/* Reset all pixels in buffer to clear color */
	glClear(GL_COLOR_BUFFER_BIT);

	glPushMatrix();

	/* Rotate buffer x y z */
	glRotatef(spin, 0.0, 0.0, 1.0);

	/* Draw rectangle by coordinate pairs x1,y1 x2,y2 */
	glRectf(-25.0, -25.0, 25.0, 25.0);

	glPopMatrix();

	/* Switch buffers displaying rendering to the screen */
	glutSwapBuffers(); 
}

void spinDisplay(void) {	/* Increase the rotation angle and render */
	spin += 2.0;
	if (spin >= 360.0) {	/* Limit the rotation angle to [0,360) */
		spin -= 360;
	}
	display();
}

void myinit(void) {	/* Initialize OpenGL default values */
	int w,h;

	/* Window geometry - Width, Height */
	w = 400;	
	h = 400;

	/* OpenGL defaults */
	glClearColor(1.0, 0.0, 0.0, 1.0);	/* Background Color */
	glColor3f(1.0,1.0,0.0);	/* Foreground Color */
	glViewport(0,0,w,h);	/* Viewable area includes entire window geometry */

	/* Default orientation */
	glOrtho(-50.0, 50.0, -50.0*(float)h/(float)w, 50.0*(float)h/(float)w, -1.0, 1.0);
}


int main(int argc, char** argv) {
	/* Initializes GLUT and processes any command line arguments */
        glutInit(&argc, argv); 

	/* Create a double buffer using the RGB color scheme */
        glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB ); 

	/* Define Window Geometry */
        glutInitWindowSize(400, 400); 

	/* Create window with string argument as title */
        glutCreateWindow("My Box"); 

	/* Initialize OpenGL */
	myinit();

	/* Register the spinDisplay function to run while idle (continuously) */
	glutIdleFunc(spinDisplay);

	/* Register Rendering function */
        glutDisplayFunc(display); 

	/* Initialize GLUT Event Handler */
        glutMainLoop();
}