#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <SDL.h>
#include <SDL_ttf.h>

int scw = 800;
int sch = 600;

int mapw = 512;
int maph = 512;

char* my_itoa(unsigned int val)
{
	static char buf[11];
	short i=10;
	for(;val&&i;--i,val/=10)buf[i]="0123456789"[val%10];
	return &buf[i+1];
}

double mygettime()
{
  struct timeval tv;
  if(gettimeofday(&tv, 0) < 0)
  {
    perror("oops");
  }
  return (double)tv.tv_sec + (0.000001 * (double)tv.tv_usec);
}

void filldata (int *hei)
{
    int p = 0;
    int x,y;
    for (y=0; y<maph; y++)
    {
        for (x=0; x<mapw; x++)
        {
            double x1 = (x-mapw/2)*0.3;
            double y1 = (y-maph/2)*0.3;
            hei[p] = 100*sin(sqrt(x1*x1+y1*y1))/(1+sqrt(x1*x1+y1*y1));
            
            p++;
        }
    }
}

void fillpalette (SDL_Surface *screen)
{
    SDL_Color colors[256];
    int i;
//     Fill colors with color information
    for(i=0;i<=256;i++)
    {
        colors[i].r=i;
        colors[i].g=i/2;
        colors[i].b=i/2;
    }
    SDL_SetPalette(screen, SDL_LOGPAL|SDL_PHYSPAL, colors, 0, 256);
}

void checkevents(float *ang, int *x, int *y, int *k)
{
    SDL_Event event;
    if (SDL_PollEvent(&event))
    {
        switch (event.type) {
        case SDL_QUIT:
            exit(0);
        }
    }
    Uint8 *keystate = SDL_GetKeyState (NULL);
    if (keystate[SDLK_LEFT]) *ang += 0.02;
    if (keystate[SDLK_RIGHT]) *ang -= 0.02;
    if (keystate[SDLK_UP]) *k -= 1;
    if (keystate[SDLK_DOWN]) *k += 1;
    if (keystate[SDLK_a] || keystate[SDLK_d] || keystate[SDLK_w] || keystate[SDLK_s])
    {
        int xd, yd;
        xd = 0;
        yd = 0;
        if (keystate[SDLK_a]) xd = -3;
        if (keystate[SDLK_d]) xd = 3;
        if (keystate[SDLK_w]) yd = 3;
        if (keystate[SDLK_s]) yd = -3;
        
        *x += yd*cos(*ang) + xd*sin(*ang);
        *y += -yd*sin(*ang) + xd*cos(*ang);
    }
}

void blacken_screen (SDL_Surface *screen)
{
    SDL_Rect rect;
    rect.x = 0;
    rect.y = 0;
    rect.w = scw;
    rect.h = sch;

    SDL_FillRect (screen, &rect, 0);
}

int main ()
{
    if ( SDL_Init(SDL_INIT_VIDEO) < 0 )
    {
        fprintf(stderr, "Cannot initialize SDL: %s\n", SDL_GetError());
        exit(1);
    }

    if (TTF_Init()==-1)
    {
        printf ("Error Init TTF\n");
        exit(1);
    }
    
    TTF_Font *font = TTF_OpenFont ("tahoma.ttf", 24);
    SDL_Color fontcolor;
    fontcolor.r = 255;
    fontcolor.g = 255;
    fontcolor.b = 255;

    SDL_Rect dest;
    dest.x = 20;
    dest.y = 20;
    SDL_Surface *textrend = TTF_RenderText_Solid (font, "FPS: ", fontcolor);
    
    SDL_Surface *screen;
    screen = SDL_SetVideoMode(scw, sch, 8, SDL_SWSURFACE);
    if ( screen == NULL )
    {// Если установить разрешение не удалось
        fprintf(stderr, "Cannot set resolution %ix%i: %s\n", scw, sch, SDL_GetError());
        exit(1);
    }

    fillpalette (screen);
    int hei[mapw*maph-1];
    filldata (hei);
    SDL_Surface *text = SDL_LoadBMP ("./testtext3.bmp");
    if (!text) printf ("Error\n");
    Uint8 *col = text->pixels;

    int posx = 0;
    int posy = 0;

    float ang = 0;
    int k = 4;

    int dd = 65536;
    int de = dd * 128; // 228 is the max "distance"
    int d;

    long x,y,z;

    float amax = M_PI/3.4;
    float a;
    float da;
    int sx;

    int maxh;

    int bin1 = (mapw*(maph-1))<<16;
    int bin2 = ((maph-1))<<16;

    double time1 = mygettime();
    double time2;
    int frames = 0;

//    long foo = d/200;
//    int bar = dd/200;
    while (1)
    {
        SDL_LockSurface(screen);
        blacken_screen (screen);

        int startidx = ((posx*mapw) & bin1) + (posy&bin2);
        int starth = hei[startidx];
        int posz = 100;

        a = -amax;
        da = 2*amax/scw;
        
        int dx = dd*(cos(ang)-a*sin(ang));
        int dy = -dd*(sin(ang)+a*cos(ang));

        int ddx = dd*sin(ang)*da;
        int ddy = dd*cos(ang)*da;

        for (sx=0;sx<scw;sx++)
        {
            int d;
            int p = sx + scw*(sch-1);
            int dz = dd*k;
            
            x = posx<<16;
            y = posy<<16;
            z = posz<<16;
            for (d=dd/2; d<=de; d+=dd)
            {
                x += dx;
                y += dy;
                z -= dz;

                int idx = (((x*mapw)&bin1)+(y&bin2))>>16;

                int h = hei[idx]<<16;
                Uint8 color = col[idx];
                while (h>z)
                {
                    *((Uint8*)screen->pixels+p) = color;
                    z += d/200;
                    dz -= dd/100;
                    p -= scw;
                }
            }
            a += da;
            dx += ddx;
            dy += ddy;
        }

        
        SDL_UnlockSurface(screen);
        SDL_BlitSurface (textrend, NULL, screen, &dest);
        SDL_Flip (screen);
        checkevents (&ang, &posx, &posy, &k);
        
        frames++;
        
        time2 = mygettime() - time1;
        if (time2 > 1.0)
        {
            SDL_FreeSurface (textrend);
            char fpsstring[30] = "FPS: ";
            strcat (fpsstring, my_itoa (frames));
            textrend = TTF_RenderText_Solid (font, fpsstring, fontcolor);
            frames = 0;
            time1 = mygettime();
        }
    }
}