/*=================================================================
 MenuExample
 Adapted from square.c by H. Masterman
 to illustrate the use of menus in glut.

 Version 1.0 February 2005
 Version 2.0 September 2005 minor revisions
 Version 3.2 February 2009 Ported to Visual Studio 2005
 Version 4.0 February 2011 minor revisions

===================================================================*/

#include <glut.h>
#include <stdlib.h>
#include <iostream>
using namespace std;

/* globals */

GLsizei wh = 700, ww = 700; // initial window size 
GLfloat size = 6.0;   // half side length of square 
int global_x_position, global_y_position;   //stores where the figure is to be drawn

float r=1.0,g=1.0,b=1.0;  // to store the global color variables
enum {square, triangle} current_shape; // stores the current selected shape


//This function draws a square polygon of 2*size in the current color
void drawSquare(int x, int y)
{
	y=wh-y;  //because the window coordinate system is flipped in y
	
	glBegin(GL_POLYGON);  //drawing the polygon
	glVertex2f((float)x+size, (float)y+size);
	glVertex2f((float)x-size, (float)y+size);
	glVertex2f((float)x-size, (float)y-size);
	glVertex2f((float)x+size, (float)y-size);
	glEnd();
	
	glFlush();  //insure that the commands clear the pipeline
}

//This function draws a trianglular polygon in the current color
void drawTriangle(int x, int y)
{
	y=wh-y;  //because the window coordinate system is flipped in y
	
	glBegin(GL_POLYGON);
	glVertex2f((float)x, (float)y+size);
	glVertex2f((float)x-0.866f*size, (float)y-0.5f*size);
	glVertex2f((float)x+0.866f*size, (float)y-0.5f*size);
	glEnd();
	
	glFlush(); //insure that the commands clear the pipeline
}

//this callback is called whenever the window is resized or moved
//also called initially, so I included the view initialization here also

void myReshape(GLsizei w, GLsizei h)
{
	cout << "in reshape" << endl; // so we will know we are in the reshape callback
	//it is customary OpenGL style to set the viewing projection in the Reshape Function
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	//set up an orthographic view with the same coordinate size as the current windo
	glOrtho(0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
	glViewport(0,0,w,h);  // set viewport to use the entire window
	
	ww = w;  //reset the global width and height variables to current window size
	wh = h; 

}

void accept_left_button_command(int btn, int state, int x, int y)
{
 
	if(btn==GLUT_LEFT_BUTTON && state==GLUT_DOWN) //this is only for left button events
	
	{
	global_x_position = x;  //capture x mouse position in global
	global_y_position = y;  //capture y mouse position in global
	glutPostRedisplay();  // post a display event
	}
		
}

// display callback

void display(void)
{
    cout << "in display" << endl; // just so you will know when display is called

	glColor3f(r,g,b); // set the color to the current color
	
	if (current_shape == triangle) drawTriangle(global_x_position, global_y_position);
	else if (current_shape == square) drawSquare(global_x_position, global_y_position);
	
	glFlush(); //insure that commands are executed
	 
}

//shape select callback sets the global current_shape
void shape_select(int shape)
{
	if (shape == 0) current_shape = square;
	else if (shape == 1) current_shape = triangle;
}

//callback for the color selection menu sets globals, r,g,b
void color_select (int color)
{
	if(color == 1) {r = 1.0; g = 0.0; b = 0.0;} //red
   else if(color == 2) {r = 0.0; g = 1.0; b = 0.0;} //green
   else if(color == 3) {r = 0.0; g = 0.0; b = 1.0;} //blue
   else if(color == 4) {r = 0.0; g = 1.0; b = 1.0;} //cyan
   else if(color == 5) {r = 1.0; g = 0.0; b = 1.0;} //magenta
   else if(color == 6) {r = 1.0; g = 1.0; b = 0.0;} //yellow
   else if(color == 7) {r = 1.0; g = 1.0; b = 1.0;} //white
   else if(color == 8) {r = 0.0; g = 0.0; b = 0.0;} //black
}

void main_menu_callback(int selection)
{
	if (selection == 0) exit(0);  // exit the program if exit is selected
	else if (selection == 1) //clear screen
	{
		glClear(GL_COLOR_BUFFER_BIT);
		glFlush();
	}
	else if (selection == 2) size = size*1.5f; //scale the size of global size multiplier
}

void set_up_menu(void)
{
	int c_menu_id, shape_menu_id; // menu identifiers for submenus

	//create a color menu with callback color_select and assign to menu id c_menu_id
    c_menu_id = glutCreateMenu(color_select);
    glutAddMenuEntry("Red",1);
    glutAddMenuEntry("Green",2);
    glutAddMenuEntry("Blue",3);
    glutAddMenuEntry("Cyan",4);
    glutAddMenuEntry("Magenta",5);
    glutAddMenuEntry("Yellow",6);
    glutAddMenuEntry("White",7);
    glutAddMenuEntry("Black",8);

	//create a shape menu with callback shape_select and menu id shape_menu_id
	shape_menu_id = glutCreateMenu(shape_select);
	glutAddMenuEntry("Square", 0);
	glutAddMenuEntry("Triangle", 1);
	
	//create the main menu
	//we don't need the main menu id so don't save it
	glutCreateMenu(main_menu_callback);

	//attach the color and shape menus to the main menu as submenus
	glutAddSubMenu("Select Color", c_menu_id);
	glutAddSubMenu("Select Shape", shape_menu_id);

	glutAddMenuEntry("Exit",0);  //this is not a submenu -> calls callback
	glutAddMenuEntry("Clear Screen",1);
	glutAddMenuEntry("Increase Size", 2);
	glutAttachMenu(GLUT_RIGHT_BUTTON);  //attach menu to right button


}

	

int main(int argc, char** argv)
{
	glutInit(&argc,argv);  // this initializes glut
	glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);  // set up the frame buffer
	glutInitWindowSize(700,700); // this is the default window size
	glutCreateWindow("Menu Example"); // creates and names the window
	// here is where we register all of the callback functions for glut
	glutReshapeFunc (myReshape);
	glutMouseFunc (accept_left_button_command);
	glutDisplayFunc(display);
	set_up_menu(); // build pop up menu
	glutMainLoop(); // enter the event loop waiting for input

}