/* $Revision$ */

#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include "SDL.h"
#include "sdl.h"
#include "map.h"

#define MEERESSPIEGEL 48
#define BLICKWEITE    55
#define FLUGHOEHE     100
#define MAPSIZE       256

int sintab[360];
int costab[360];
char map[MAPSIZE*MAPSIZE];
SDL_Surface *screen;

void init_tabs() {
	int x;

	for (x=0;x<360; x++) 
		sintab[x] = (int) (127.0 * sin(x*M_PI/180));
	for (x=0; x < 90; x++)
		costab[x] = sintab[x+90];
	for (x=90; x < 360; x++)
  		costab[x] = -sintab[x-90];
}

void fly(SDL_Surface *screen) {
	static int 
		posx = 0,
		posy = 0,
		richtung = 0,
		flughoehe = 0;
	int iy, ix, iy1, iyp, ixp;
	int x, y, z, s, i, j;
	int map_color;
	int rng[WIDTH];

	if(SDL_MUSTLOCK(screen))
                if(SDL_LockSurface(screen) < 0) {
                        fprintf(stderr, "Can't lock screen: %s\n",
                                        SDL_GetError());
                        return;
                }
	
	/* Richtung wechseln? */
	if (rand()<RAND_MAX/2) {
		if (rand()<RAND_MAX) {
			if (richtung <= 0) { richtung = 357; }
			else { richtung -= 3; }
		} else {
			if (richtung >= 357) { richtung = 0; }
			else { richtung += 3; }
		}
	}
	
	/* Bewegen ... */	
	posy = posy + costab[richtung] / 32;
	posx = posx + sintab[richtung] / 32;

	posy %= MAPSIZE; if(posy<0) posy+=MAPSIZE;
	posx %= MAPSIZE; if(posx<0) posx+=MAPSIZE;

	/* Absolute Höhe berechnen */
	flughoehe = FLUGHOEHE + map[posy*MAPSIZE+posx]/2;
	
	/* FIXME */
	for (i=0;i<WIDTH;i++) rng[i] = HEIGHT;
  

	SDL_FillRect(screen, NULL, 0);
	
	for (iy=posy; iy<=posy+BLICKWEITE; iy++) {
		iy1 = 2 * (iy-posy) + 1;
		s = 4 + (WIDTH-20) / iy1;

		for (ix=posx-(iy-posy); ix<=posx+(iy-posy); ix++) {

			ixp = posx 
				+ ((ix-posx) * costab[richtung] 
				+ (iy-posy) * sintab[richtung]) /(MAPSIZE/2);
			iyp = posy 
				+ ((iy-posy) * costab[richtung]
				- (ix-posx) * sintab[richtung]) /(MAPSIZE/2);

			x = WIDTH/2 + 360*(ix-posx) / iy1;

			if(
				(x>=0) && (x+s<=WIDTH-2) 
				&& ((MAPSIZE*iyp+ixp) > 0) 
				&& ((MAPSIZE*iyp+ixp) < MAPSIZE*MAPSIZE)
			) {
		    
				map_color = map[MAPSIZE*iyp+ixp];
				z         = map[MAPSIZE*iyp+ixp];
				if(z<MEERESSPIEGEL) z = MEERESSPIEGEL;
				y = HEIGHT/2 + 30 * (flughoehe-z) / iy1;

				if ((y>=0) && (y<=HEIGHT-1)) {
				for (j=x;j<=x+s;j++)
				for (i=rng[j];i>=y;i--) {
					if ((WIDTH*i+j>=0) && (WIDTH*i+j<WIDTH*HEIGHT))
					sdl_putpixel(screen, j, i, map_color);
					if (y<rng[j]) rng[j] = y;
				}}
			}
		}
	}

        if(SDL_MUSTLOCK(screen)) SDL_UnlockSurface(screen);
	SDL_UpdateRect(screen, 0, 0, WIDTH, HEIGHT);

	usleep(1000*1000/25);
}

int main(void) {
	init_tabs();
	map_init(map,MAPSIZE,MAPSIZE);
	map_generate(map,0,0,MAPSIZE-1,MAPSIZE-1);

	screen = sdl_init();
        map_setpalette(screen);

	while(1) {
		fly(screen);
	}
	
	sleep(30); SDL_Quit(); exit(0);
}