// 0.  Compile and run the code.  Left click in the window, and choose the menu options.
//     Are they functional?

// 1.  Complete the code so that the menus three options are functional:
//     (a) quit
//     (b) double the size of the box
//     (c) halve the size of the box

// 2.  Finally, modify the code so that a main menu provides the option of choosing
//     from two subMenus:
//         (a) a color menu, which changes the color of the box
//         (b) a size menu which functions as above


#include <GL/glut.h>
#include <cstdlib>

#define WINDOWSIZE 400

GLint size = 100;

void myInit()
{
	glClearColor(1.0,1.0,1.0,0.0);
	glColor3f(0.0,0.0,0.0);

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0.0,WINDOWSIZE,0.0,WINDOWSIZE);
	glMatrixMode(GL_MODELVIEW);
}

void display()
{
	glClear(GL_COLOR_BUFFER_BIT);

	glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);

	glBegin(GL_POLYGON);
		glVertex2f(0.0,0.0);
		glVertex2f(size,0.0);
		glVertex2f(size,size);
		glVertex2f(0.0,size);
	glEnd();

	glFlush();
}

void firstMenu (GLint id)
{
	switch (id) {
		case 1:
			exit(0);
			break;
		case 2:
			size *= 2;
			break;
		case 3:
			size /= 2;
			break;
	}
	glutPostRedisplay();
}

void sizeMenu (GLint id)
{
	switch (id) {
		case 2:
			size *= 2;
			break;
		case 3:
			size /= 2;
			break;
	}
	glutPostRedisplay();
}
void colorMenu (GLint id)
{
	switch (id) {
		case 4:
			glColor3f(1.0,0.0,0.0);
			break;
		case 5:
			glColor3f(0.0,0.0,1.0);
			break;
	}
	glutPostRedisplay();
}

void mainMenu (GLint id)
{
	switch (id) {
	case 1:
		exit(0);
		break;
	}
	glutPostRedisplay();
}


int main (int argc , char **argv)
{
	GLint subMenu1, subMenu2;

	glutInit(&argc,argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(WINDOWSIZE,WINDOWSIZE);
	glutInitWindowPosition(0.0,0.0);
	glutCreateWindow("MenuDemo");
	myInit();
	glutDisplayFunc(display);


	/*
	// #1
	glutCreateMenu(firstMenu);
	glutAddMenuEntry("quit",1);
	glutAddMenuEntry("bigger square",2);
	glutAddMenuEntry("smaller square",3);
	glutAttachMenu(GLUT_LEFT_BUTTON);
	*/

	//
	// #2
	subMenu1=glutCreateMenu(sizeMenu);
		glutAddMenuEntry("bigger square",2);
		glutAddMenuEntry("smaller square",3);
	subMenu2=glutCreateMenu(colorMenu);
		glutAddMenuEntry("red",4);
		glutAddMenuEntry("blue",5);
	glutCreateMenu(mainMenu);
		glutAddMenuEntry("quit",1);
		glutAddSubMenu("size",subMenu1);
		glutAddSubMenu("color",subMenu2);
	glutAttachMenu(GLUT_LEFT_BUTTON);
	//

	glutMainLoop();

	return 0;
}