#include <windows.h>
#include <gl\gl.h>
#include <gl\glut.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>

int width = 400;
int height = 400;
int shape = 0;

// Anti-aliased Point Size Info
GLfloat ps_range[2];
GLfloat ps_gran;
GLfloat ps = 5.0;

// Anti-aliased Line Width Info
GLfloat lw_range[2];
GLfloat lw_gran;
GLfloat lw = 5.0;


double drand ()
{
  return rand() / (double)(RAND_MAX + 1);
}


void draw ()
{
  // Clear buffers
  glClear(GL_COLOR_BUFFER_BIT);

  // Reset viewport
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  // Draw current shape
  switch(shape)
  {
  case 0:
    glBegin(GL_POINTS);
    break;
  case 1:
    glBegin(GL_LINES);
    break;
  case 2:
    glBegin(GL_LINE_STRIP);
    break;
  case 3:
    glBegin(GL_LINE_LOOP);
    break;
  case 4:
    glBegin(GL_TRIANGLES);
    break;
  case 5:
    glBegin(GL_TRIANGLE_STRIP);
    break;
  case 6:
    glBegin(GL_TRIANGLE_FAN);
    break;
  case 7:
    glBegin(GL_QUADS);
    break;
  case 8:
    glBegin(GL_QUAD_STRIP);
    break;
  case 9:
    glBegin(GL_POLYGON);
    break;
  };

  // Draw random verticies
  for (int i = 0; i < 24; i++)
  {
    glColor3f(drand(), drand(), drand());
    glVertex3f(drand()*width, drand()*height, 0);
  }

  glEnd();

  // Put buffer on screen
  glutSwapBuffers();
}


void keys (unsigned char key, int x, int y)
{
  GLboolean b;
  GLint k;

  switch (key)
  {
  // Exit Program
  case 'q':
  case 'Q':
  case 27:
    exit(0);
    break;

  // Toggle Line Anti-aliasing
  case 'l':
    glGetBooleanv(GL_LINE_SMOOTH, &b);
    if (b)
      glDisable(GL_LINE_SMOOTH);
    else
      glEnable(GL_LINE_SMOOTH);
    break;

  // Toggle Point Anti-aliasing
  case 'p':
    glGetBooleanv(GL_POINT_SMOOTH, &b);
    if (b)
      glDisable(GL_POINT_SMOOTH);
    else
      glEnable(GL_POINT_SMOOTH);
    break;

  // Toggle the Shading Model
  case 's':
    glGetIntegerv(GL_SHADE_MODEL, &k);
    if (k == GL_SMOOTH)
      glShadeModel(GL_FLAT);
    else
      glShadeModel(GL_SMOOTH);
    break;

  // Cycle Current Shape
  case '[':
    shape = --shape % 10;
    break;
  case ']':
    shape = ++shape % 10;
    break;

  // Cycle Line/Point Size
  case '+':
  case '=':
    if (shape == 0 && ps + 1.0 <= ps_range[1])
      ps += 1.0;
    else if (shape > 0 && lw + 1.0 <= lw_range[1])
      lw += 1.0;
    glPointSize(ps);
    glLineWidth(lw);
    break;
  case '-':
  case '_':
    if (shape == 0 && ps - 1.0 >= ps_range[0])
      ps -= 1.0;
    else if (shape > 0 && lw - 1.0 >= lw_range[0])
      lw -= 1.0;
    glPointSize(ps);
    glLineWidth(lw);
    break;
  };

  // Force OpenGL to redraw screen
  glutPostRedisplay();
}


int main (int argc, char **argv)
{
  // Setup OpenGL
  glutInit(&argc, argv);
  glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE);
  glutInitWindowSize(width, height);
  glutCreateWindow("Shapes");

  // Setup callbacks
  glutDisplayFunc(draw);
  glutKeyboardFunc(keys);

  // Setup viewport
  glMatrixMode(GL_PROJECTION);
  glOrtho(0, width, 0, height, -1000, 1000);

  // Change background color
  glClearColor(0, 0, 0, 0);

  // Collect Point Size Info
  glGetFloatv(GL_POINT_SIZE_RANGE, ps_range);

  // Collect Line Width Info
  glGetFloatv(GL_LINE_WIDTH_RANGE, lw_range);

  // Setup Point Size
  glPointSize(ps);

  // Setup Line Width
  glLineWidth(lw);

  // Setup random
  srand(time(NULL));

  // Give control to OpenGL
  glutMainLoop();
	return 0;
}