/*  binary_clock.c  show date and time     */

#include <GL/glut.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <stdlib.h>

static int points[6][4];
static int width=200;
static int height=75;
static char date[] = "month day year";
static int oldsec = 0;
static int tohex[10][4] = {{0, 0, 0, 0},
                           {1, 0, 0, 0},
                           {0, 1, 0, 0},
                           {1, 1, 0, 0},
                           {0, 0, 1, 0},
                           {1, 0, 1, 0},
                           {0, 1, 1, 0},
                           {1, 1, 1, 0},
                           {0, 0, 0, 1},
                           {1, 0, 0, 1}};

static void display(void)
{
  char *p;
  int i, j, nj;

  /* clear window */
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity ();
  glColor3f(0.0, 0.0, 0.0);
  
  /* draw text, in its own context */
  glPushMatrix();
    glLoadIdentity ();
    glColor3f(0.0, 0.0, 0.0);
    glTranslatef(0.05, 0.8, 0.0);
    glScalef(0.00075, 0.0015, 0.0);
    for(p=date; *p; p++)
      glutStrokeCharacter(GLUT_STROKE_ROMAN, *p);
  glPopMatrix();

  /* Draw the binary time */
  glColor3f(0.0, 1.0, 0.0);
  glPointSize(8.0);
  for(i=0; i<6; i++)
  {
    nj = 4;
    if(i==0) nj=2;
    if(i==2 || i==4) nj=3;
    for(j=0; j<nj; j++)
    {
      if(points[i][j]==1) glColor3f(0.0, 1.0, 0.0);
      else                glColor3f(0.85, 0.85, 0.85);
      glBegin(GL_POINTS);
        glVertex3f(0.1+i*0.15, 0.1+j*0.15, 0.0);
      glEnd();
    }
  }
  glFlush(); 
} /* end display */

/* This routine handles window resizes */
static void reshape(int w, int h)
{
  width = w;
  height = h;
  /* Set the transformations */
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0);
  glMatrixMode(GL_MODELVIEW);
  glViewport(0, 0, w, h);
  glutPostRedisplay();
} /* end reshape */

static void init()
{
  int i, j, nj;

  /* set clear color to white */
  glClearColor (1.0, 1.0, 1.0, 0.0);
  /* set fill  color to green */
  glColor3f(0.0, 1.0, 0.0);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0);
  glMatrixMode (GL_MODELVIEW);
  glViewport(0, 0, width, height);
  for(i=0; i<6; i++)
  {
    for(j=0; j<4; j++) points[i][j]=0;
    nj = 4;
    if(i==0) nj=2;
    if(i==2 || i==4) nj=3;
    for(j=0; j<nj; j++)
    {
      points[i][j]=1; /* all on light test */
    }
  }
} /* end init */

static void tick()
{
  time_t mytime;
  struct tm *today;
  int i, j;
  int nowsec, hour;
  int d[6];

  mytime = time(&mytime);
  today = localtime(&mytime);
  nowsec = today->tm_sec;
  while(nowsec==oldsec)
  {
    mytime = time(&mytime);
    today = localtime(&mytime);
    nowsec = today->tm_sec;
  }
  oldsec = nowsec;
  hour = today->tm_hour;
  if(hour>12) hour = hour-12;
  d[0] = hour/10;
  d[1] = hour%10;
  d[2] = today->tm_min/10;
  d[3] = today->tm_min%10;
  d[4] = today->tm_sec/10;
  d[5] = today->tm_sec%10;
  for(i=0; i<6; i++)
  {
    for(j=0; j<4; j++)
    {
      points[i][j]=tohex[d[i]][j];
    }
  }
  sprintf(date,"%d / %d / %d \n",
          today->tm_mon+1, today->tm_mday, today->tm_year+1900);
  glutPostRedisplay();
} /* end tick */

int main(int argc, char* argv[])
{
  glutInit(&argc,argv);
  glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);  
  glutInitWindowSize(width, height);
  glutInitWindowPosition(600,40); 
  
  glutCreateWindow(argv[0]); 
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutIdleFunc(tick);
  init();
  glutMainLoop();
  return 0;
} /* end main of binary_clock.c */