#include "SDL/SDL.h"
#include <math.h>

#ifndef PI
#define PI  3.14159265358979323846
#endif

#define VIDEOX 320
#define VIDEOY 240

#define TABLEX VIDEOX*2
#define TABLEY VIDEOY*2
#define TONES 256

  double r[3];
  double R[6];
  unsigned char *t;

  int rands[512];
  int lastRandI = 0;

static void do_plasma(SDL_Surface*surface,
           double x1,
           double y1,
           double x2,
           double y2,
           double x3,
           double y3,
           unsigned char*t)
{
  unsigned int
    X1=x1*(TABLEX/2),
    Y1=y1*(TABLEY/2),
    X2=x2*(TABLEX/2),
    Y2=y2*(TABLEY/2),
    X3=x3*(TABLEX/2),
    Y3=y3*(TABLEY/2);
  unsigned int y;
  unsigned char *t1=t+X1+Y1*TABLEX, *t2=t+X2+Y2*TABLEX, *t3=t+X3+Y3*TABLEX;
  for (y=0; y<VIDEOY; y++) {
    unsigned x;
    unsigned char*tmp= ((Uint8*)surface->pixels) + y * surface->pitch;
    unsigned int t=y*TABLEX, tmax=t+VIDEOX;
    for (x=0; t<tmax; t++, tmp++) {
      tmp[0]=t1[t]+t2[t]+t3[t];
    }
  }
}

int main ()
{
  SDL_Surface *screen;
  SDL_Color colors[TONES*2];

  int starttime, endtime, realtime;
  int i, state=0;

  /* randomized stuff */
  startcrand(SDL_GetTicks(), 99999999);
  {
    int c;
    for (c=0; c<3; c++)
      r[c]=((double)(crand()%1000+1))/300000;
    for (c=0; c<6; c++)
      R[c]=((double)(crand()%1000+1))/5000;
  }


  /* Inizialize the SDL library */
  if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
    fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
    return 1;
  }


  screen=SDL_SetVideoMode(VIDEOX, VIDEOY, 8, SDL_SWSURFACE);
  if ( screen == NULL ) {
    fprintf(stderr, "Couldn't initialize video mode: %s\n", SDL_GetError());
    return 1;
  }

  SDL_nFont *font = SDL_nLoadFont(NSP_FONT_THIN, SDL_MapRGB(screen->format, 255,0,60),NSP_FONT_DEFAULT);
  SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 0, 0, 100));
  SDL_nDrawString(screen, font, 120, 110, "Loading...");
  SDL_Flip(screen);

  precalculateTable();

  SDL_EventState(SDL_ACTIVEEVENT, SDL_IGNORE);
  SDL_EventState(SDL_MOUSEMOTION, SDL_IGNORE);


  /* Main loop */
  while (SDL_PollEvent(NULL)==0) {
    starttime=SDL_GetTicks();
    state++;
    {
      int c;
      for (c=0 ; c<TONES; c++) {
    colors[c].r=(sin(((double)c)/TONES*6*PI+r[0]*PI*state*PI)+1)*127;
    colors[c].g=(sin(((double)c)/TONES*6*PI+r[1]*state*PI)+1)*127;
    colors[c].b=(sin(((double)c)/TONES*6*PI+r[2]*state*PI)+1)*127;
      }
      SDL_SetColors(screen, colors, 0, TONES);
    }
    if (SDL_LockSurface(screen) <0 ) {
      continue;
    }
    do_plasma(screen,
    (sin(((double)state)*R[0])+1)/2,
    (sin(((double)state)*R[1])+1)/2,
    (sin(((double)state)*R[2])+1)/2,
    (sin(((double)state)*R[3])+1)/2,
    (sin(((double)state)*R[4])+1)/2,
    (sin(((double)state)*R[5])+1)/2, t);
    SDL_UnlockSurface(screen);
    SDL_Flip(screen);
    endtime = SDL_GetTicks();
    //limit frame draw time to a minimum of 40ms (25fps)
    if((endtime-starttime)<40){
        sleep(40-(endtime-starttime));
        realtime = SDL_GetTicks()-starttime;
    }
  }
  printf("Time to draw last frame was %d ms (%d fps)\n",endtime-starttime,1000/(endtime-starttime));
  if((endtime-starttime)<40)
    printf("But was forced to %d ms (%d fps)\n",realtime,1000/realtime);
  SDL_Quit();
  return 0;
}

void precalculateTable()
{
  printf("Precalculating table...\n");
  t = (unsigned char *)malloc(TABLEY*TABLEX);
  if ( t == NULL ) {
    fprintf(stderr, "Out of memory\n");
    exit(1);
  }
  {
    int y;
    for (y=0 ; y<TABLEY ; y++) {
      int x;
      for (x=0 ; x<TABLEX ; x++) {
    double tmp=(((double)((x-(TABLEX/2))*(x-(TABLEX/2))+(y-(TABLEX/2))*(y-(TABLEX/2))))
            *(PI/(TABLEX*TABLEX+TABLEY*TABLEY)));
    t[y*TABLEX+x]=(sin(sqrt(tmp)*12)+1)*TONES/6;
      }
    }
  }
}


//RAND functions


void startcrand(int seed, int max){

    printf("Starting pseudorandom number generator...\n");


    if(seed>max){
        printf("Oops: seed is bigger than max\n");
        exit(-1);
        }

    if(seed == 0){
        printf("Oops: seed is 0 - setting it to 1337\n");
        seed = 1337;
    }

    printf("Seed is %d\n",seed);



    int a = 5; //multiplier
    int c = 3; //increment

    int i; //iterator

    printf("Generating random numbers.. \n");
    for(i=0; i<500; i++)
    {
        seed = (a * seed + c) % max;

        rands[i] = seed;


    }
    printf("Done!\n");
}



int crand(){

    if(lastRandI > 490)
        lastRandI = 2;

    lastRandI++;


    return rands[lastRandI];
}