#include <u.h>#include <libc.h>#include <libg.h>#include "fns.h"#define	XMAX	800#define	YMAX	1024 #define	MAXBOOMS	10#define	MAXSHARDS	30#define	DX		4	/* Power of 2 */#define	TIMELEFT	30	/* Number of clock ticks before fade */struct boom{	int	active;	struct shard{		int	x;		int	y;		int	dx;		int	dy;		int	timeleft;	}s[MAXSHARDS];}boom[MAXBOOMS]; voidexstart(int x, int y){	struct boom *b;	struct shard *s;	for(b=boom; b<&boom[MAXBOOMS]; b++)		if(b->active==0){			b->active++;			for(s=b->s; s<&b->s[MAXSHARDS]; s++){				s->x=_max(x, 1);				s->x=_min(x, XMAX-2);				s->y=_max(y, 1);				s->y=_min(y, YMAX-2);				s->dx=((rand()>>8)&(2*DX-1))-DX;				s->dy=((rand()>>8)&(2*DX-1))-DX;				s->timeleft=(TIMELEFT/2)+(rand()>>8)%TIMELEFT;			}			return;		}} intexmove(void){	struct boom *b;	struct shard *s;	int shardalive;	int boomalive;	boomalive=0;	for(b=boom; b<&boom[MAXBOOMS]; b++)		if(b->active){			shardalive=0;			for(s=b->s; s<&b->s[MAXSHARDS]; s++){				if(s->timeleft==0)					continue;				if(--s->timeleft<=0)					exblob(s->x, s->y, 0);				else{					shardalive++;					exblob(s->x, s->y, 0);					s->x+=s->dx;					s->y+=s->dy;					if(s->x>=1 && s->x<XMAX-1 && s->y>=1 && s->y<YMAX-1)						exblob(s->x, s->y, 1);					else						s->timeleft=1;	/* get it next time */				}			}			if(shardalive==0)				exclear(b);			else				boomalive++;		}	return(boomalive);} voidexinit(void){	struct boom *b;	for(b=boom; b<&boom[MAXBOOMS]; b++)		exclear(b);} voidexclear(struct boom *b){	register struct shard *s;	if(b->active){		for(s=b->s; s<&b->s[MAXSHARDS]; s++)			if(s->timeleft)				exblob(s->x, s->y, 0);		b->active=0;	}} voidexblob(int x, int y, int bit){	USED(bit);	point(&screen, Pt(x, y), ~0, F&~D);} int_min(int a, int b){	return(a<b? a : b);} int_max(int a, int b){	return(a>b? a : b);}