#include <cstdlib>
#include <iostream>
#include <cmath>
#include <GL/glut.h>
using namespace std;

// typedefs
typedef unsigned char uchar;

// constants 
const int BOXSIZE = 20;
const int NUMCOLORS = 7;

// struct
struct s_point{
  int x, y, color;
};

// static vars
static s_point *points = NULL;
static int cur_color = 0;
static int num_points = 0;
static int height;

// callbacks 
void keyb(uchar key, int x, int y);
void disp(void);
void resize(int x, int y);
void mouse(int button, int state, int x, int y);

// prototypes
void drawQuad(int x, int y,int delta);

////////////////////////////////
// main
int main(int argc,char  **argv){
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
  glutInitWindowSize(500,500);
  glutInitWindowPosition(100,100);
  glutCreateWindow("Polygon.cpp");
 
  glClearColor(0.0,0.0,0.0,0.0);
  glutKeyboardFunc(keyb);
  glutDisplayFunc(disp);
  glutReshapeFunc(resize);
  glutMouseFunc(mouse);
  glutMainLoop();
  return 0;

}

////////////////////////////////////////////////
// mouse
void mouse(int button, int state, int x, int y){
  
  // if left mouse down 
  if(button == GLUT_LEFT && state == GLUT_DOWN){

    // are we clicking in the pallette ?
    if((x < BOXSIZE) && (abs(y-height) < (NUMCOLORS * BOXSIZE))){
      // if we are in the pallette, change the current color
      cur_color = abs(y-height)/BOXSIZE;

      // or have we clicked in the screen ?
    }else{
      s_point * temp = new  s_point[num_points+1];

      // copy the old to a temporary
      for(int i=0;i<(num_points);i++){
	temp[i].x = points[i].x;
	temp[i].y = points[i].y;
	temp[i].color = points[i].color;
      }

      // save the new one
      temp[num_points].x = x;
      temp[num_points].y = height - y;
      temp[num_points].color = cur_color;

      // increment the number of points
      num_points++;
      // delete the old 
      delete [] points;
      // make the temporary the current one
      points = temp;
      // ask for a redisplay
      glutPostRedisplay();
    }
  }
}

///////////////////////////////////
// keyb
void keyb(uchar key, int x, int y){
  switch(key){
  case 'q':
    delete [] points;
    exit(0);
    break;
  case 'w':
    cout << "Wireframe mode on " << endl;
    glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
    glutPostRedisplay();
    break;
  case 'p':
    cout << "Point mode on " << endl;
    glPolygonMode(GL_FRONT_AND_BACK,GL_POINT);
    glutPostRedisplay();
    break;
  case 'f':
    cout << "Fill mode on " << endl;
    glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
    glutPostRedisplay();
    break;
  case 's':
    cout << "Smooth shading " << endl;
    glShadeModel(GL_SMOOTH);
    glutPostRedisplay();
    break;
  case 'b':
    cout << "Flat shading " << endl;
    glShadeModel(GL_FLAT);
    glutPostRedisplay();
    break;
  }
};

////////////////
// disp
void disp(void){

  // define colors
  static float colorarray[NUMCOLORS][3] =
    {
      {1.0,1.0,1.0},
      {0.0,1.0,1.0},
      {0.0,0.0,1.0},
      {1.0,1.0,0.0},
      {1.0,0.0,0.0},
      {0.0,1.0,0.0},
      {1.0,0.0,1.0}
    };
  
  glClear(GL_COLOR_BUFFER_BIT);
 
  // draw the palette 
  int ypos = 0;
  for(int i=0;i<NUMCOLORS;i++){
    glColor3fv(colorarray[i]);
    drawQuad(0,ypos,BOXSIZE);
    ypos+=BOXSIZE;
  }

  glBegin(GL_POLYGON);
  for(int i=0;i<num_points;i++){
    glColor3fv(colorarray[points[i].color]);
    glVertex2f(points[i].x,points[i].y);
  }
  glEnd();
  glutSwapBuffers();
}

//////////////////////////////////////
// drawQuad
void drawQuad(int x, int y, int delta){
  glBegin(GL_QUADS);
  glVertex2f(x,y);
  glVertex2f(x+delta,y);
  glVertex2f(x+delta,y+delta);
  glVertex2f(x,y+delta);
  glEnd();
}

//////////////////////////
// resize
void resize(int x, int y){
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluOrtho2D(0,x,0,y);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  height = y;
}