#include <u.h>#include <libc.h>#include <draw.h> #include <bt.h> typedef struct Agent Agent;struct Agent {	Point pos;	Point target;}; intpstate(int state){	print(" -> %s\n", btstatenames[state]);	return state;} /* find a random place to goto */intwpfind(void *ctx, void *a){	Agent *agent = a; 	print("wander find");	agent->target = Pt(nrand(11), nrand(11));	return pstate(TASKSUCCESS);} /* find an enemy */intafind(void *ctx, void *a){	Agent *agent = a; 	print("find"); 	if(nrand(8) == 0){		agent->target = Pt(nrand(11), nrand(11));		return pstate(TASKSUCCESS);	} 	return pstate(TASKFAIL);} /* move towards the enemy */intamove(void *ctx, void *a){	Agent *agent = a; 	print("move"); 	if((abs(agent->pos.x - agent->target.x) + abs(agent->pos.y - agent->target.y)) < 2)		return pstate(TASKSUCCESS); 	if(agent->target.x > agent->pos.x){		agent->pos.x++;		return pstate(TASKRUNNING);	} 	if(agent->target.x < agent->pos.x){		agent->pos.x--;		return pstate(TASKRUNNING);	} 	if(agent->target.y > agent->pos.y){		agent->pos.y++;		return pstate(TASKRUNNING);	} 	if(agent->target.y < agent->pos.y){		agent->pos.y--;		return pstate(TASKRUNNING);	} 	return pstate(TASKFAIL);} /* simulate hitting an enemy */intahit(void *ctx, void *a){	print("hit"); 	if(nrand(4) == 0)		return pstate(TASKSUCCESS);	return pstate(TASKRUNNING);} BehaviorNode*mkbt(void){	BehaviorNode *find, *move, *hit;	BehaviorNode *wfind, *wmove, *wander;	BehaviorNode *attack, *idle;	BehaviorNode *root; 	find = btleaf("find enemy", afind, nil);	move = btleaf("move to target", amove, nil); 	/* die yankee pig dog */	hit = btleaf("hit enemy", ahit, nil); 	/* combat ai is a simple search and destroy */	attack = btsequence("attack enemy", find, move, hit, nil); 	wfind = btleaf("wander find", wpfind, nil);	wmove = btleaf("wander move", amove, nil);	wander = btsequence("wander", wfind, wmove, nil); 	/* find is added here so control will pop out of	 * wander when an enemy is found	 */ 	idle = btparallel("wander", 1, 2, find, wander, nil); 	root = btpriority("root", attack, idle, nil);	return root;} voidtest_bt(void){	int i, state;	Agent a;	BehaviorNode *root;	Behavior *b;	BehaviorState *bs; 	a.pos = Pt(0, 0);	a.target = Pt(-1, -1); 	root = mkbt();	b = btroot(root);	bs = btstatenew(b); 	for(i = 0; i < 100; i++){		print("======== TICK ========\n");		print("pos=%P target=%P %T\n", a.pos, a.target, root);		state = bttick(b, bs, &a);		print(" -> %s\n", btstatenames[state]);		sleep(10);	} 	btstatefree(bs, &a);	btfree(b);} voidusage(void){	fprint(2, "usage: %s\n", argv0);	exits("usage");} voidmain(int argc, char *argv[]){	ARGBEGIN{	default:		usage();	}ARGEND 	fmtinstall('P', Pfmt);	fmtinstall('T', btfmt); 	alarm(5000); 	srand(truerand()); 	test_bt(); 	exits(nil);}