3d scene

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

//#define DEBUG_PRINT(A) printf A
#define DEBUG_PRINT(A) ;

#ifndef max
    #define max( a, b ) ( ((a) > (b)) ? (a) : (b) )
#endif

#ifndef min
    #define min( a, b ) ( ((a) < (b)) ? (a) : (b) )
#endif

int bsize = 2;

int scw = 1280;
int sch = 1024;

int mapa = 32;
int mapb = 32;
int mapc = 128;

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 *col)
{
    int idx,startidx;
    int x,y,z;
    for (y=0; y<mapb; y++)
    {
        for (x=0; x<mapa; x++)
        {
            if ((x>10)&&(x<30)&&(y>10)&&(y<30))
            {
                startidx = y*mapa*mapb + x*mapa;
                hei[startidx] = 4;
                hei[startidx+1] = 25;
            }

            int dist = (x-20)*(x-20)+(y-20)*(y-20);
            if (dist<=81)
            {
                hei[startidx+4] = 40;
                hei[startidx+5] = 41+x;

                hei [startidx+2] = 80;
                hei [startidx+3] = 100;
            }

            for (z=0; z<mapc; z++)
            {
                idx = y*mapa*mapb + x*mapa + z;
                col[idx] = 3*sqrt(x*x+y*y+z*z);
            }
        }
    }
}

void fillpalette (SDL_Surface *screen)
{
    SDL_Color colors[256];
    int i;

    for(i=0;i<=256;i++)
    {
        colors[i].r=i;
        colors[i].g=i/3;
        colors[i].b=i/3;
    }
    SDL_SetPalette(screen, SDL_LOGPAL|SDL_PHYSPAL, colors, 0, 256);
}

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);
}

void checkevents(double *ang, int *x, int *y, int *z, int *k)
{
    SDL_Event event;
    if (SDL_PollEvent(&event))
    {
        switch (event.type) {
        case SDL_KEYDOWN:
            if (event.key.keysym.sym == 'q')
            {
                TTF_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_k]) *z -= 1;
    if (keystate[SDLK_j]) *z += 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);
    }
}

int main ()
{
    int hei[mapa*mapb*mapc-1];
    int col[mapa*mapb*mapc-1];

    memset (hei, -1, sizeof(int)*mapa*mapb*mapc);
    filldata (hei, col);

    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|SDL_HWPALETTE|SDL_FULLSCREEN);
    if ( screen == NULL )
    {
        fprintf(stderr, "Cannot set resolution %ix%i: %s\n", scw, sch, SDL_GetError());
        exit(1);
    }

    fillpalette (screen);

    int posx = 0;
    int posy = 0;
    int posz = 80;

    double ang = 0;
    int k = 1;

    double dd = 1;
    double de = dd * 228; // 128 is the max "distance"
    int x,y,z;

    double amax = M_PI/3.4; // FOV
    double a;

    int bin1 = mapb*mapb*mapb-mapa*mapa;
    int bin2 = mapa*mapa-mapa;
    int bin3 = mapc-1;

    int sx;

    int minsytop[scw-1];
    int maxsybottom[scw-1];
    int areas;

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

    while (1)
    {
        SDL_LockSurface(screen);

        blacken_screen (screen);

        double sinang = sin(ang);
        double cosang = cos(ang);

        for (sx=0;sx<scw;sx++)
        {
            memset (minsytop, -1, sizeof(int)*scw);
            memset (maxsybottom, -1, sizeof(int)*scw);
            minsytop[0] = 0;
            maxsybottom[0] = sch-1;
            areas = 1;

            double d;
            a = -amax + 2*amax*sx/scw;
            for (d=0;d<=de;d+=dd)
            {
                double y1 = d*/*cos(amax)**/tan(a);
                double x1 = d;//*cos(amax);

                x = posx + x1*cosang+y1*sinang;
                y = posy - x1*sinang+y1*cosang;
                z = posz - k*d;//*sin(amax);

                int idx = ((y*mapa*mapb)&bin1) + ((x*mapa)&bin2);
                int zi;

                DEBUG_PRINT (("Inside d\n"));

                for (zi=0; zi<mapc/2; zi++)
                {
                    int idxstart = idx + zi*2;
                    int hstart = hei[idxstart];

                    int idxend = idx + zi*2 + 1;
                    int hend = hei[idxend];

                    if (hstart==-1) break;

                    DEBUG_PRINT (("gstart = %i, hend = %i\n", hstart, hend));

                    int sy = sch/2 + 150*(z-hstart)/(d+1);
                    int sy2 = sch/2 + 150*(z-hend)/(d+1);

                    int area;
                    for (area=0; area<areas; area++)
                    {
                        DEBUG_PRINT (("Area = %i\n", area));
                        int top = minsytop[area];
                        int bottom = maxsybottom[area];
                        if (top==-1) break;

                        int ovsy2 = max (top, sy2);
                        int ovsy = min (bottom, sy);

                        DEBUG_PRINT (("sy = %i, sy2 = %i\n", sy, sy2));
                        DEBUG_PRINT (("bottom = %i, top = %i\n", bottom, top));

                        if (ovsy2<sch)
                        {
                            if (ovsy>=sch) ovsy = sch-1;
                            if (ovsy2<0) ovsy2 = 0;
                            int syi;
                            for (syi=ovsy; syi>=ovsy2; syi--)
                            {
                                *((Uint8*)screen->pixels+sx+scw*syi) = col[idx];
                            }
                        }

                        // Adjust minsytop and maxsybottom
                        if ((sy2>top)&&(sy<bottom)) //Split
                        {
                            maxsybottom[area] = sy2;
                            minsytop[areas] = sy;
                            maxsybottom[areas] = bottom;

                            areas++;
                            break;
                        }
                        //if (top==ovsy2) minsytop[area] = sy; // Correct top
                        //if (bottom==ovsy) maxsybottom[area] = sy2; // Correct bottom
                        else if ((sy2<top)&&(sy>top)&&(sy<bottom)) minsytop[area] = sy;
                        else if ((sy>bottom)&&(sy2<bottom)&&(sy2>top)) maxsybottom[area] = sy2;
                        else if ((sy2<top)&&(sy>bottom)) // Destroy area
                        {
                            memmove (maxsybottom+area, maxsybottom+area+1, sizeof(int)*(areas-area));
                            memmove (minsytop+area, minsytop+area+1, sizeof(int)*(areas-area));
                            areas--;
                        }
                    }
                    DEBUG_PRINT (("Areas %i\n", areas));
                }
            }
        }

        SDL_UnlockSurface (screen);
        SDL_BlitSurface (textrend, NULL, screen, &dest);
        SDL_Flip (screen);
        checkevents (&ang, &posx, &posy, &posz, &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();
        }
    }

    return atexit(SDL_Quit);
}