Add/Remove entities from systems when when its component bitmask changes

.github/workflows/tests.yml

@@ -30,6 +30,7 @@ jobs:
       - uses: actions/checkout@v2
       - name: Build and run tests
         run: |
+          pwd
           make clean
           make tests
           ./tests

pico_ecs.h

@@ -909,7 +909,7 @@ void* ecs_add(ecs_t* ecs, ecs_id_t entity_id, ecs_id_t comp_id, void* args)
     // belongs to
     ecs_bitset_flip(&entity->comp_bits, comp_id, true);
 
-    // Add entity to systems
+    // Add or remove entity from systems
     for (ecs_id_t sys_id = 0; sys_id < ecs->system_count; sys_id++)
     {
         ecs_sys_t* sys = &ecs->systems[sys_id];
@@ -922,6 +922,15 @@ void* ecs_add(ecs_t* ecs, ecs_id_t entity_id, ecs_id_t comp_id, void* args)
                     sys->add_cb(ecs, entity_id, sys->udata);
             }
         }
+        else // Just remove the entity if its components no longer match for whatever reason.
+        {
+            if (!ecs_bitset_is_zero(&sys->exclude_bits) && 
+                 ecs_sparse_set_remove(&sys->entity_ids, entity_id))
+            {
+                if (sys->remove_cb)
+                    sys->remove_cb(ecs, entity_id, sys->udata);
+            }
+        }
     }
 
     // Return component
@@ -956,6 +965,15 @@ void ecs_remove(ecs_t* ecs, ecs_id_t entity_id, ecs_id_t comp_id)
                     sys->remove_cb(ecs, entity_id, sys->udata);
             }
         }
+        else
+        {
+            if (!ecs_bitset_is_zero(&sys->exclude_bits) && 
+                 ecs_sparse_set_add(ecs, &sys->entity_ids, entity_id))
+            {
+                if (sys->add_cb)
+                    sys->add_cb(ecs, entity_id, sys->udata);
+            }
+        }
     }
 
     ecs_comp_t* comp = &ecs->comps[comp_id];
@@ -1310,7 +1328,7 @@ static size_t ecs_sparse_set_find(ecs_sparse_set_t* set, ecs_id_t id)
 {
     ECS_ASSERT(ecs_is_not_null(set));
 
-    if (set->sparse[id] < set->size && set->dense[set->sparse[id]] == id)
+    if (id < set->capacity && set->sparse[id] < set->size && set->dense[set->sparse[id]] == id)
         return set->sparse[id];
     else
         return ECS_NULL;

tests_pico_ecs/main.c

@@ -97,6 +97,21 @@ TEST_CASE(test_exclude)
     REQUIRE(exclude_sys_state.count == 1);
     REQUIRE(exclude_sys_state.eid == eid2);
 
+    // Removing comp1 from entity1 causes it to be added to the system
+    ecs_remove(ecs, eid1, comp1_id);
+    ecs_update_system(ecs, system_id, 0.0);
+
+    REQUIRE(exclude_sys_state.count == 2);
+    REQUIRE(exclude_sys_state.eid == eid2);
+
+    // Adding comp1 to entity2 causes it to be removed from the system
+    ecs_add(ecs, eid2, comp1_id, NULL);
+
+    ecs_update_system(ecs, system_id, 0.0);
+
+    REQUIRE(exclude_sys_state.count == 1);
+    REQUIRE(exclude_sys_state.eid == eid1);
+
     return true;
 }