/* This program illustrates the use of the glut library for
interfacing with a window system */

/* Description of operation of program is in Chapter 2*/

#define NULL 0
#include <GL/glut.h>

void mouse(int, int, int, int);
void display(void);
void idle(void);
void drawSquare(int, int);
void myReshape(GLsizei, GLsizei);

void myinit(void);

void screen_box(int, int, int);
void right_menu(int);
void middle_menu(int);
void color_menu(int);
void pixel_menu(int);
void fill_menu(int);
long time(int);
int pick(int, int);

/* globals */

GLsizei wh = 500, ww = 500; /* initial window size */
GLfloat size = 3.0;   /* half side length of square */

int base; /* font list base */
long baset; /*time base */
GLfloat r = 1.0, g = 1.0, b = 1.0; /* drawing color */
int fill = 0; /* fill flag */



void drawSquare(int x, int y)
{

        y=wh-y;
        glColor3ub( (char) random()%256, (char) random()%256, (char) random()%256); 
        glBegin(GL_POLYGON);
                glVertex2f(x+size, y+size);
                glVertex2f(x-size, y+size);
                glVertex2f(x-size, y-size);
                glVertex2f(x+size, y-size);
        glEnd();
}


/* rehaping routine called whenever window is resized
or moved */

void myReshape(GLsizei w, GLsizei h)
{

/* adjust clipping box */

        glMatrixMode(GL_PROJECTION);
        glLoadIdentity(); 
        glOrtho(0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity(); 

/* adjust viewport and  clear */

        glViewport(0,0,w,h);
    glClearColor (1.0, 1.0, 1.0, 1.0);
        glClear(GL_COLOR_BUFFER_BIT);
        display();
        glFlush();

/* set global size for use by drawing routine */

        ww = w;
        wh = h; 
}

void myinit(void)
{

/* set up a font in display list */
    int i;
baset = time(0);
        base = glGenLists(128);
    for(i=0;i<128;i++)
                {
                glNewList(base+i, GL_COMPILE);
                glutBitmapCharacter(GLUT_BITMAP_9_BY_15, i);
                glEndList();
        }
        glListBase(base);

        glViewport(0,0,ww,wh);

/* Pick 2D clipping window to match size of X window 
This choice avoids having to scale object coordinates
each time window is resized */

        glMatrixMode(GL_PROJECTION);
        glLoadIdentity(); 
        glOrtho(0.0, (GLdouble) ww , 0.0, (GLdouble) wh , -1.0, 1.0);

/* set clear color to black and clear window */

        glClearColor (0.0, 0.0, 0.0, 1.0);
        glClear(GL_COLOR_BUFFER_BIT);
        glFlush();
}



void mouse(int btn, int state, int x, int y)
{
    static int draw_mode = 0; /* drawing mode */
    static int count;
    int where;
    static int xp[2],yp[2];
    if(btn==GLUT_LEFT_BUTTON && state==GLUT_DOWN) 
    {
       glPushAttrib(GL_ALL_ATTRIB_BITS);
       glutIdleFunc(NULL);
       
       where = pick(x,y);
       glColor3f(r, g, b);
       if(where != 0)
       {
          count = 0;
          draw_mode = where;
       }
       else if(draw_mode == 1  &&  count == 0)
       {
              count = 1;
              xp[0] = x;
              yp[0] = y;
       }
       else if(draw_mode == 1  &&  count != 0)
       {
              glBegin(GL_LINES); 
                 glVertex2i(x,wh-y);
                 glVertex2i(xp[0],wh-yp[0]);
              glEnd();
              draw_mode=0;
              count=0;
       }
       else if(draw_mode == 2  &&  count == 0)
       {
              count = 1;
              xp[0] = x;
              yp[0] = y;
       }
       else if(draw_mode == 2  &&  count != 0) 
       {
              if(fill) glBegin(GL_POLYGON);
              else glBegin(GL_LINE_LOOP);
                 glVertex2i(x,wh-y);
                 glVertex2i(x,wh-yp[0]);
                 glVertex2i(xp[0],wh-yp[0]);
                 glVertex2i(xp[0],wh-y);
              glEnd();
              draw_mode=0;
              count=0;
       }
       else if(draw_mode == 3  &&  count == 0)
       {
              count = 1;
              xp[0] = x;
              yp[0] = y;
       }
       else if(draw_mode == 3  &&  count == 1)
       {
              count = 2;
              xp[1] = x;
              yp[1] = y;
       }
       else if(draw_mode == 3  &&  count == 2)
       {
              if(fill) glBegin(GL_POLYGON);
              else glBegin(GL_LINE_LOOP);
                 glVertex2i(xp[0],wh-yp[0]);
                 glVertex2i(xp[1],wh-yp[1]);
                 glVertex2i(x,wh-y);
              glEnd();
              draw_mode=0;
              count=0;
       }
       else if(draw_mode == 4 )
       {
          drawSquare(x,y);
          count++;
       }

       glutIdleFunc(idle);
       glPopAttrib();
       glFlush();
     }
}

int pick(int x, int y)
{
    y = wh - y;
    if(y < wh-ww/10) return 0;
    else if(x < ww/10) return 1;
    else if(x < ww/5) return 2;
    else if(x < 3*ww/10) return 3;
    else if(x < 2*ww/5) return 4;
    else return 0;
}

void screen_box(int x, int y, int s )
{
    glBegin(GL_QUADS);
      glVertex2i(x, y);
      glVertex2i(x+s, y);
      glVertex2i(x+s, y+s);
      glVertex2i(x, y+s);
    glEnd();
}

void idle(void)
{

    char out[]="00:00:00";
    long t, time();
    int min, sec, hr;


    glPushAttrib(GL_ALL_ATTRIB_BITS);
    t=time(0)-baset;
    hr=t/3600;
    min = (t - 3600*hr) /60;
    sec = (t - 3600*hr - 60*min);
    hr = hr%24;
    out[0]='0'+hr/10;
    out[1]='0'+hr%10;
    out[3]='0'+min/10;
    out[4]='0'+min%10;
    out[6]='0'+sec/10;
    out[7]='0'+sec%10;
    glRasterPos2i(ww-80, wh-15);
    glColor3f(0.0,0.0,0.0);
    glBegin(GL_QUADS);
        glVertex2i(ww-80, wh-15);
        glVertex2i(ww, wh-15);
        glVertex2i(ww, wh);
        glVertex2i(ww-80, wh);
    glEnd();
    glColor3f(1.0,1.0,1.0);
    glCallLists( strlen(out) , GL_BYTE, out);
    glFlush();
    glPopAttrib();
}

void right_menu(int id)
{
   glutIdleFunc(NULL);
   if(id == 1) exit();
   else display();
   glutIdleFunc(idle);
}

void middle_menu(int id)
{
   glutIdleFunc(NULL);
   glutIdleFunc(idle);

}

void color_menu(int id)
{
   glutIdleFunc(NULL);
   if(id == 1) {r = 1.0; g = 0.0; b = 0.0;}
   else if(id == 2) {r = 0.0; g = 1.0; b = 0.0;}
   else if(id == 3) {r = 0.0; g = 0.0; b = 1.0;}
   else if(id == 4) {r = 0.0; g = 1.0; b = 1.0;}
   else if(id == 5) {r = 1.0; g = 0.0; b = 1.0;}
   else if(id == 6) {r = 1.0; g = 1.0; b = 0.0;}
   else if(id == 7) {r = 1.0; g = 1.0; b = 1.0;}
   else if(id == 8) {r = 0.0; g = 0.0; b = 0.0;}
   glutIdleFunc(idle);
}


void pixel_menu(int id)
{
   glutIdleFunc(NULL);
   if (id == 1) size = 2 * size;
   else if (size > 1) size = size/2;
   glutIdleFunc(idle);
}

void fill_menu(int id)
{
   glutIdleFunc(NULL);
   if (id == 1) fill = 1; 
   else fill = 0;
   glutIdleFunc(idle);
}

void display(void)
{
    glPushAttrib(GL_ALL_ATTRIB_BITS);
    glutIdleFunc(NULL);
    glClearColor (0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    glColor3f(1.0, 1.0, 1.0);
    screen_box(0,wh-ww/10,ww/10);
    glColor3f(1.0, 0.0, 0.0);
    screen_box(ww/10,wh-ww/10,ww/10);
    glColor3f(0.0, 1.0, 0.0);
    screen_box(ww/5,wh-ww/10,ww/10);
    glColor3f(0.0, 0.0, 1.0);
    screen_box(3*ww/10,wh-ww/10,ww/10);
    glColor3f(0.0, 0.0, 0.0);
    screen_box(ww/10+ww/40,wh-ww/10+ww/40,ww/20);
    glBegin(GL_LINES);
       glVertex2i(wh/40,wh-ww/20);
       glVertex2i(wh/40+ww/20,wh-ww/20);
    glEnd();
    glBegin(GL_TRIANGLES);
       glVertex2i(ww/5+ww/40,wh-ww/10+ww/40);
       glVertex2i(ww/5+ww/20,wh-ww/40);
       glVertex2i(ww/5+3*ww/40,wh-ww/10+ww/40);
    glEnd();
    glPointSize(3.0);
    glBegin(GL_POINTS);
       glVertex2i(3*ww/10+ww/20, wh-ww/20);
    glEnd();

    glutIdleFunc(idle);
    glFlush();
    glPopAttrib();
}


int main(int argc, char** argv)
{
    int c_menu, p_menu, f_menu;

    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutCreateWindow("square");
    glutDisplayFunc(display);

    c_menu = glutCreateMenu(color_menu);
    glutAddMenuEntry("Red",1);
    glutAddMenuEntry("Green",2);
    glutAddMenuEntry("Blue",3);
    glutAddMenuEntry("Cyan",4);
    glutAddMenuEntry("Magenta",5);
    glutAddMenuEntry("Yellow",6);
    glutAddMenuEntry("White",7);
    glutAddMenuEntry("Black",8);

    p_menu = glutCreateMenu(pixel_menu);
    glutAddMenuEntry("increase pixel size", 1);
    glutAddMenuEntry("decrease pixel size", 2);

    f_menu = glutCreateMenu(fill_menu);
    glutAddMenuEntry("fill on", 1);
    glutAddMenuEntry("fill off", 2);

    glutCreateMenu(right_menu);
    glutAddMenuEntry("quit",1);
    glutAddMenuEntry("clear",2);
    glutAttachMenu(GLUT_RIGHT_BUTTON);

    glutCreateMenu(middle_menu);
    glutAddSubMenu("Colors", c_menu);
    glutAddSubMenu("Pixel Size", p_menu);
    glutAddSubMenu("Fill", f_menu);
    glutAttachMenu(GLUT_MIDDLE_BUTTON);

    myinit ();
    glutReshapeFunc (myReshape); 
    glutMouseFunc (mouse);
    glutIdleFunc(idle); 
    glutMainLoop();

}