ArnCarveris · April 2, 2024 08:06 · Apr 2, 2024
diff --git a/flecs_bt.c b/flecs_bt.c
@@ -0,0 +1,318 @@
+#include <https://raw.githubusercontent.com/SanderMertens/flecs/master/flecs.h>
+#include <https://raw.githubusercontent.com/SanderMertens/flecs/master/flecs.c>
+#include <https://gist.github.com/ArnCarveris/535cf7c25007271bfa75d6396853a4a3/raw/99b57783a906995b4b89c4fb8d053c0ed2981603/flecs_godbolt.h>
+
+typedef struct {
+  float x, y;
+} Position, Velocity;
+
+typedef struct {
+    float time;
+} Timer;
+
+typedef struct {
+    ecs_query_t *q;
+    ecs_entity_t parent;
+    ecs_iter_t it;
+    int i;
+    int j;
+    char n;
+} ecs_enum_t;
+
+
+// Forward declare component so we can use it from functions other than main
+ECS_COMPONENT_DECLARE(Position);
+ECS_COMPONENT_DECLARE(Velocity);
+ECS_COMPONENT_DECLARE(Timer);
+
+
+ECS_TAG_DECLARE(IsAction);
+ECS_TAG_DECLARE(IsRunning);
+ECS_TAG_DECLARE(IsFailed);
+ECS_TAG_DECLARE(IsSucceeded);
+
+ecs_enum_t ecs_enum_new( ecs_world_t *ecs, ecs_query_t *q, ecs_entity_t e)
+{
+    ecs_enum_t self;
+    self.q = q;
+    self.parent = e;
+    self.it =  ecs_query_iter(ecs, self.q);
+    ecs_query_set_group(&self.it, e);
+    self.i = 0;
+    self.j = 0;
+    self.n = 1;
+
+    return self;
+}
+
+void ecs_enum_reset(ecs_enum_t* self)
+{
+    self->it =  ecs_query_iter(self->it.world, self->q);
+    ecs_query_set_group(&self->it, self->parent);
+    self->i = 0;
+    self->j = 0;
+    self->n = 1;
+}
+
+int ecs_enum_next(ecs_enum_t* self)
+{
+    if (self->n)
+    {
+        self->n = 0;
+        self->j = 0;
+
+        if (!ecs_query_next(&self->it))
+            return 0;
+    }
+
+    self->i = self->j++;
+
+    if (self->i < self->it.count)
+        return 1;
+
+    self->n = 1;
+
+    return ecs_enum_next(self);
+}
+
+ecs_entity_t ecs_enum_entity(ecs_enum_t* self)
+{
+    return self->it.entities[self->i];
+}
+
+
+void print_tab(int tab)
+{
+    for(int i = 0; i <= tab; ++i)
+        printf("    ");
+}
+
+void print_entity(int tab, ecs_world_t *ecs, ecs_entity_t e) {
+    char *path_str = ecs_get_fullpath(ecs, e);
+    char *type_str = ecs_type_str(ecs, ecs_get_type(ecs, e));
+    print_tab(tab);
+    printf("#%d %s [%s] ", e, path_str, type_str);
+    ecs_os_free(type_str);
+    ecs_os_free(path_str);
+}
+
+void print_tree(int tab, ecs_world_t *ecs, ecs_query_t* q, ecs_entity_t e) {
+    // Print hierarchical name of entity & the entity type
+    print_entity(tab, ecs, e);
+    printf("\n");
+    ++tab;
+    // Iterate children recursively
+    for (ecs_enum_t i = ecs_enum_new(ecs, q, e); ecs_enum_next(&i);) 
+    {
+        print_tree(tab, ecs, q, ecs_enum_entity(&i));   
+    }
+}
+
+
+void ecs_bt_remove_states(ecs_world_t *world, ecs_entity_t target, ecs_entity_t action)
+{
+    ecs_remove_pair(world, target, IsRunning, action);   
+    ecs_remove_pair(world, target, IsFailed, action);   
+    ecs_remove_pair(world, target, IsSucceeded, action);   
+}
+
+void ecs_bt_change_state(ecs_world_t *world, ecs_entity_t target, ecs_entity_t state)
+{
+    ecs_entity_t action = ecs_get_target(world, target, IsRunning, 1);
+
+    if (action == 0)
+        action = ecs_get_target(world, target, IsRunning, 0);
+
+    if (action == 0)
+        return;
+
+    ecs_remove_pair(world, target, IsRunning, action);
+    ecs_add_pair(world, target, state, action); 
+
+    //printf("ecs_bt_change_state: #%d action: ", target); print_entity_name(world, action);
+    //printf(" state: "); print_entity_name(world, state); printf("\n");
+}
+
+
+int ecs_bt_first(ecs_enum_t* self, ecs_world_t *world, ecs_entity_t target)
+{
+    if (!ecs_enum_next(self))
+        return 0;
+
+    ecs_entity_t action = ecs_enum_entity(self);
+
+    ecs_add_pair(world, target, EcsIsA, action);    
+    ecs_add_pair(world, target, IsRunning, action); 
+
+    return 1;
+}
+
+int ecs_bt_next(ecs_enum_t* self,  ecs_world_t *world, ecs_entity_t target, ecs_entity_t action)
+{
+    ecs_remove_pair(world, target, EcsIsA, action);    
+    ecs_bt_remove_states(world, target, action);
+    if (!ecs_enum_next(self))
+        return 0;
+
+    action = ecs_enum_entity(self);
+
+    ecs_add_pair(world, target, EcsIsA, action);    
+    ecs_add_pair(world, target, IsRunning, action); 
+
+    return 1;
+}
+
+void ecs_bt_parent(ecs_enum_t* self, ecs_world_t *world, ecs_entity_t target, ecs_entity_t state)
+{
+    ecs_bt_remove_states(world, target, self->parent);
+    ecs_add_pair(world, target, state, self->parent);
+}
+
+ecs_entity_t ecs_bt_sequence(ecs_enum_t* self, ecs_world_t *world, ecs_entity_t target)
+{
+    ecs_entity_t state = IsFailed;
+
+    if (self->n)
+    {
+        if (ecs_bt_first(self, world, target))
+            state = IsRunning;
+    }
+    else
+    {
+        ecs_entity_t action = ecs_enum_entity(self);
+
+        if (ecs_has_pair(world, target, EcsIsA, action))
+        {
+            if (ecs_has_pair(world, target, IsRunning, action))
+                state = IsRunning;
+            else if (ecs_has_pair(world, target, IsSucceeded, action))
+                if (ecs_bt_next(self, world, target, action))
+                    state = IsRunning;
+                else
+                    state = IsSucceeded;
+        }
+        else
+        {
+            if (ecs_bt_first(self, world, target))
+                state = IsRunning;
+        }
+    }
+
+    ecs_bt_parent(self, world, target, state);
+
+    if (state == IsSucceeded)
+        ecs_enum_reset(self);
+
+    return state;
+}
+
+void print_bt(int tab, ecs_world_t* ecs, ecs_query_t* q, ecs_entity_t behaviour, ecs_entity_t agent, int ticks, float dt)
+{
+    ecs_enum_t bt = ecs_enum_new(ecs, q, behaviour);
+
+    for (int i = 0; i < ticks; ++i) 
+    {
+        printf("\n -~> %d/%d \n", i+1, ticks);
+
+        ecs_bt_sequence(&bt, ecs, agent);
+        print_entity(tab, ecs, agent); 
+        ecs_progress(ecs, dt);
+    }
+
+}
+
+void Move(ecs_iter_t *it) {
+  Position *p = ecs_field(it, Position, 1);
+  Velocity *v = ecs_field(it, Velocity, 2);
+
+  for (int i = 0; i < it->count; i++) {
+    p[i].x += v[i].x;
+    p[i].y += v[i].y;
+     printf("Move(%f, %f)\n", p[i].x, p[i].y); 
+    ecs_bt_change_state(it->real_world, it->entities[i], IsSucceeded);
+  }
+}
+
+void Wait(ecs_iter_t *it) {
+  Timer *t = ecs_field(it, Timer, 1);
+
+  for (int i = 0; i < it->count; i++) {
+    t[i].time -= it->delta_time;
+
+     printf("Wait(%f)\n", t[i].time); 
+
+    if (t[i].time > 0)
+        continue;
+
+    ecs_bt_change_state(it->world, it->entities[i], IsSucceeded);
+
+    //FIXME: it should be automatically removed on (IsA) bc `Timer` component is overriden
+    ecs_remove(it->world, it->entities[i], Timer);
+  }
+}
+
+
+int main(int argc, char *argv[]) {
+
+    ecs_world_t *ecs = ecs_init_for_godbolt(argc, argv);
+
+    ECS_COMPONENT_DEFINE(ecs, Position);
+    ECS_COMPONENT_DEFINE(ecs, Velocity);
+    ECS_COMPONENT_DEFINE(ecs, Timer);
+
+    ECS_TAG_DEFINE(ecs, IsAction);
+    ECS_TAG_DEFINE(ecs, IsRunning);
+    ECS_TAG_DEFINE(ecs, IsFailed);
+    ECS_TAG_DEFINE(ecs, IsSucceeded);
+
+    ECS_SYSTEM(ecs, Move, EcsOnUpdate, Position, Velocity);
+    ECS_SYSTEM(ecs, Wait, EcsOnUpdate, Timer);
+
+    ecs_query_t* q = ecs_query(ecs, {
+        .filter.terms = {
+            { .id = ecs_pair(EcsChildOf, EcsWildcard) },
+            { .id = EcsPrefab, .oper = EcsOptional }
+        },
+        .group_by_id = EcsChildOf,
+        .order_by = flecs_entity_compare,
+    });
+
+
+    ecs_entity_t seq = ecs_new_prefab(ecs, "Seq");
+
+    {
+        ecs_entity_t move = ecs_new_prefab(ecs, "1Move");
+        ecs_add_pair(ecs, move, EcsChildOf, seq);
+        ecs_add_pair(ecs, Move, IsAction, move);
+        ecs_set(ecs, move, Velocity, {1, 1});
+    }  {
+        ecs_entity_t wait = ecs_new_prefab(ecs, "2Wait");
+        ecs_add_pair(ecs, wait, EcsChildOf, seq);
+        ecs_add_pair(ecs, Wait, IsAction, wait);
+        ecs_set(ecs, wait, Timer, {1});
+        ecs_override(ecs, wait, Timer);
+
+    } {
+        ecs_entity_t move = ecs_new_prefab(ecs, "3Move");
+        ecs_add_pair(ecs, Move, IsAction, move);
+        ecs_add_pair(ecs, move, EcsChildOf, seq);
+        ecs_set(ecs, move, Velocity, {-3, 3});
+    }
+
+    printf("actions: \n");
+    print_tree(0, ecs, q, Move);
+    print_tree(0, ecs, q, Wait);
+    printf("behaviours: \n");
+    print_tree(0, ecs, q, seq);
+
+    printf("agents: \n");
+    ecs_entity_t agent = ecs_new_entity(ecs, "Agent");
+    ecs_set(ecs, agent, Position, {10, 20});
+
+    print_bt(0, ecs, q, seq, agent, 20, 0.5);
+
+    printf("\nfini: \n");
+
+
+    return ecs_fini(ecs);
+}