//================================================================
//    planet.cc
//    ÂÀÍ۷ϤÎÏÇÀ±¤Î°ÌÃÖ¤òÉÁ¤¯CGI
//    Copyright (C) Naoki Watanabe. 1995-1999. All rights reserved.
//================================================================

#include <math.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include "ppmgraph.h"

const int    IMG_WIDTH  = 256;
const int    IMG_HEIGHT = 256;
const int    XC         = IMG_WIDTH/2;
const int    YC         = IMG_HEIGHT/2;
const double MAG        = 72.0;

struct Planet
{
  double r, omg, tho;  // radius, anglur velocity, initial angle.
  char   fname[32]; // file name of the PPM.
  
  //---- Calculate the position at the given time.
  void Position( time_t t, double& x, double& y ){
    x = r*cos(omg*t+tho);
    y = r*sin(omg*t+tho);
  }
};

// Radius is given in Astronomic unit (mean span between Sun and Earth).
// Anglur velocity is given in rad/sec.
// Initial angle is given in rad, which is the angle
// at 00:00:00 on Jan 1, 2000.

// Set data for Sun and four planets.
Planet planets[5]= {
  { 0.000, 0.000e+00, 0.000, "planet0.ppm" }, // Sun
  { 0.387, 8.265e-07, 4.429, "planet1.ppm" }, // Mercury
  { 0.723, 3.236e-07, 3.145, "planet2.ppm" }, // Venus
  { 1.000, 1.991e-07, 1.737, "planet3.ppm" }, // Earth
  { 1.523, 1.058e-07, 0.021, "planet4.ppm" }  // Mars
};

//---- Calculate seconds since the intial time 00:00:00 on Jan 1, 2000.
time_t GetTime( void )
{
  struct tm t2000;
  t2000.tm_sec   = 0;
  t2000.tm_min   = 0;
  t2000.tm_hour  = 0;
  t2000.tm_mday  = 1;
  t2000.tm_mon   = 0;
  t2000.tm_year  = 100;
  t2000.tm_wday  = 0;
  t2000.tm_yday  = 0;
  t2000.tm_isdst = 0;
  
  return time(NULL) - mktime(&t2000);
}


int main( void )
{
  double x, y;
  time_t t;
  Vram V(IMG_WIDTH, IMG_HEIGHT);

  t = GetTime();
  
  for( int i=0; i<5; i++ ){
    planets[i].Position( t, x, y );
    
    // draw an orbit.
    V.DrawCircle( XC, YC, int(planets[i].r*MAG) );
    
    // draw an image of the planet.
    V.PastePPM( XC-10+int(x*MAG), YC-10-int(y*MAG), planets[i].fname );
  }
  
  return 0;
}