#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <assert.h>
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

void display(void);
void keypress(unsigned char key, int x, int y);
float polar1(float theta, float r);
float polar2(float theta, float r);
void draw_polygon(float dx, float dy);
void main_menu(int value);
void off_menu(int value);

GLfloat red[3] = {1.0, 0.0, 0.0};
GLfloat green[3] = {0.0, 1.0, 0.0};
GLfloat blue[3] = {0.0, 0.0, 1.0};
GLfloat black[3] = {0.0, 0.0, 0.0};
GLfloat white[3] = {1.0, 1.0, 1.0};
GLfloat gray[3] = {0.5, 0.5, 0.5};
GLfloat yellow[3] = {1.0, 1.0, 0.0};
GLfloat magenta[3] = {1.0, 0.0, 1.0};
GLfloat cyan[3] = {0.0, 1.0, 1.0};

GLfloat *curCol = white;
GLint num_balls = 4;
GLint fillmode = 0;
GLint shapep = 50;
GLint *shape;


int main (int argc, char **argv) {

  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
  glutInitWindowSize(500, 500);
  glutInitWindowPosition(100,100);
  glutCreateWindow(argv[0]);

  glClearColor(0,0,0,0);
  glColor3f(1.0, 1.0, 1.0);
  shape = & shapep;

  glutDisplayFunc(display);
  glutKeyboardFunc(keypress);

  glutCreateMenu(main_menu);
  glutAddMenuEntry("red", 1);
  glutAddMenuEntry("green", 2);
  glutAddMenuEntry("blue", 3);
  glutAddMenuEntry("black", 4);
  glutAddMenuEntry("white", 5);
  glutAddMenuEntry("gray", 6);
  glutAddMenuEntry("yellow", 7);
  glutAddMenuEntry("magenta", 8);
  glutAddMenuEntry("cyan", 9);
  glutAddMenuEntry("Quit", 10);
  glutAttachMenu(GLUT_RIGHT_BUTTON);

  glutCreateMenu(off_menu);
  glutAddMenuEntry("Triangle", 3);
  glutAddMenuEntry("Square", 4);
  glutAddMenuEntry("Pentagon", 5);
  glutAddMenuEntry("Hexagon", 6);
  glutAddMenuEntry("circle", 7);
  glutAddMenuEntry("auto", 8);
  glutAttachMenu(GLUT_LEFT_BUTTON);
  

  glutMainLoop();
  return 0;
}

void display(void) {
  float i = 0;
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  

  for(i = 0; i < 2*M_PI; i = i + (2*M_PI)/num_balls) {
    glColor3f(curCol[0] + i/(2*M_PI), curCol[1] + i/(2*M_PI), curCol[2] + i/(2*M_PI));
    draw_polygon(polar1(i,.75), polar2(i,.75));

  }

  glFlush();
}
float polar1(float theta, float r) {
   return r * sin(theta);
 }
float polar2(float theta, float r) {
  return r * cos(theta);
}

void draw_polygon(float dx, float dy) {
  float i = 0;
  if(fillmode) {
  glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
  } else {
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
  }
  glBegin(GL_POLYGON);
  for(i = 0; i < 2*M_PI; i  = i+(2*M_PI/(*shape))) {
    glVertex2f(dx + polar1(i,.1),dy +  polar2(i,.1));
  }
  glEnd();
}

void keypress(unsigned char key, int x, int y) {
  switch(key) {
  case 'q':
    exit(0);
    break;
  case '+':
    num_balls++;
    break;
  case '-':
    if(num_balls > 0)
      num_balls--;
    break;
  case 'g':
    fillmode = !fillmode;
    break;
  }
  glutPostRedisplay();
}

void off_menu(int value) {
  switch (value) {
  case 7:
    *shape = 50;
    break;
  case 8:
    shape = &num_balls;
    break;
    default:
    *shape = (GLint)value;
  }
  glutPostRedisplay();
}

void main_menu(int value) {
  switch (value) {
  case 1:
    curCol = red;
    break;
  case 2:
    curCol = green;
    break;
  case 3:
    curCol = blue;
    break;
  case 4:
    curCol = black;
    break;
  case 5:
    curCol = white;
    break;
  case 6:
    curCol = gray;
    break;
  case 7:
    curCol = yellow;
    break;
  case 8:
    curCol = magenta;
    break;
  case 9:
    curCol = cyan;
    break;
  case 10:
    exit(0);

  }
  glutPostRedisplay();
}