/* 

 *

 *    This application has been modified from its original version,

 *    by Timothy A. Graupmann. For any questions or comments send

 *    email to tgraupmann@yahoo.com.

 *

 *    Example program for the Allegro library, by Shawn Hargreaves.

 *

 *    This program originally demonstrated...

 *

 *    This program demonstrates how to write directly to video memory.

 *    It implements a simple fire effect, first by calling getpixel() and

 *    putpixel(), then by accessing video memory directly a byte at a

 *    time, and finally using block memory copy operations.

 */





#include <stdlib.h>

#include <stdio.h>



#ifdef DJGPP

#include <sys/farptr.h>

#include <sys/segments.h>

#include <sys/movedata.h>

#endif



#include "allegro.h"





/* The fire is formed from several 'hotspots' which are moved randomly

 * across the bottom of the screen.

 */

#define FIRE_HOTSPOTS   75



int hotspot[FIRE_HOTSPOTS]; 

static int thotspot[FIRE_HOTSPOTS];







/* This function updates the bottom line of the screen with a pattern

 * of varying intensities which are then moved upwards and faded out

 * by the code in main().

 */

void draw_bottom_line_of_fire()

{

   int c, c2;

   unsigned char temp[320];



   /* zero the buffer */

   for (c=0; c<SCREEN_W; c++)

      temp[c] = 0;



   for (c=0; c<FIRE_HOTSPOTS; c++) { 

      /* display the hotspots */

      for (c2=hotspot[c]-20; c2<hotspot[c]+20; c2++)

	 if ((c2 >= 0) && (c2 < SCREEN_W))

	    temp[c2] = MIN(temp[c2] + 20-ABS(hotspot[c]-c2), 192);



      /* move the hotspots */

      hotspot[c] += thotspot[c];

      if (hotspot[c] < 0)

	 hotspot[c] += SCREEN_W;

      else

	 if (hotspot[c] >= SCREEN_W)

	    hotspot[c] -= SCREEN_W;

   }



   /* display the buffer */

   for (c=0; c<SCREEN_W; c++)

      putpixel(screen, c, SCREEN_H-1, temp[c]);

}







int main()

{

   for(int index=0; index<FIRE_HOTSPOTS; index++)

      thotspot[index]=rand()%3-1;

   PALLETE pal1;

   int c;

   int x, y;

   unsigned long address;

   unsigned char temp[320];



   allegro_init();

   install_keyboard(); 

   set_gfx_mode(GFX_VGA, 320, 200, 0, 0);



   for (c=0; c<FIRE_HOTSPOTS; c++)

      hotspot[c] = random() % SCREEN_W;



   /* fill our pallete with a gradually altering sequence of colors */

   for (c=0; c<64; c++) {

      pal1[c].r = c;

      pal1[c].g = 0;

      pal1[c].b = 0;

   }

   for (c=64; c<128; c++) {

      pal1[c].r = 63;

      pal1[c].g = c-64;

      pal1[c].b = 0;

   }

   for (c=128; c<192; c++) {

      pal1[c].r = 63;

      pal1[c].g = 63;

      pal1[c].b = c-192;

   }

   for (c=192; c<256; c++) {

      pal1[c].r = 63;

      pal1[c].g = 63;

      pal1[c].b = 63;

   }



   /* it's even faster if we transfer the data in big blocks */

   while (!keypressed()) {

      set_pallete(pal1);

      draw_bottom_line_of_fire();



      for (y=SCREEN_H-2; y>50; y--) {

	 /* get an address for reading line y+1 */

	 address = bmp_read_line(screen, y+1);



	 /* read the line */

	 movedata(screen->seg, address, _my_ds(), (unsigned)temp, SCREEN_W);



	 /* adjust it */

	 for (x=0; x<SCREEN_W; x++)

	    if (temp[x] > 0)

	       temp[x]--;



	 /* get an address for writing line y */

	 address = bmp_write_line(screen, y);



	 /* write the line */

	 movedata(_my_ds(), (unsigned)temp, screen->seg, address, SCREEN_W);

      }



      for (y=0; y<51; y++) {

	 /* get an address for reading line y+1 */

	 address = bmp_read_line(screen, y+1);



	 /* read the line */

	 movedata(screen->seg, address, _my_ds(), (unsigned)temp, SCREEN_W);



	 /* adjust it */

	 for (x=0; x<SCREEN_W; x++)

	    if (temp[x] > 0)

	       temp[x]--;



	 /* get an address for writing line y */

	 address = bmp_write_line(screen, y);



	 /* write the line */

	 movedata(_my_ds(), (unsigned)temp, screen->seg, address, SCREEN_W);

      }



   }



   return 0;

}