Properly link flecs library

engine/libs/flecs/examples/c/systems/mutate_entity/include/mutate_entity.h

@@ -0,0 +1,16 @@
+#ifndef MUTATE_ENTITY_H
+#define MUTATE_ENTITY_H
+
+/* This generated file contains includes for project dependencies */
+#include "mutate_entity/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/systems/mutate_entity/include/mutate_entity/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef MUTATE_ENTITY_BAKE_CONFIG_H
+#define MUTATE_ENTITY_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/systems/mutate_entity/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "mutate_entity",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/systems/mutate_entity/src/main.c

@@ -0,0 +1,83 @@
+#include <mutate_entity.h>
+#include <stdio.h>
+
+typedef struct {
+    double value;
+} Timeout;
+
+// System that deletes an entity after a timeout expires
+void Expire(ecs_iter_t *it) {
+    Timeout *t = ecs_field(it, Timeout, 1);
+
+    for (int i = 0; i < it->count; i ++) {
+        t[i].value -= (double)it->delta_time;
+        if (t[i].value <= 0) {
+            // When deleting the entity, use the world provided by the iterator.
+
+            // To make sure that the storage doesn't change while a system is
+            // iterating entities, and multiple threads can safely access the
+            // data, mutations (like a delete) are added to a command queue and
+            // executed when it's safe to do so.
+ 
+             // A system should not use the world pointer that is provided by the
+             // ecs_init function, as this will throw an error that the world is
+             // in readonly mode (try replacing it->world with it->real_world).
+            ecs_delete(it->world, it->entities[i]);
+            printf("Expire: %s deleted!\n", ecs_get_name(
+                it->world, it->entities[i]));
+        }
+    }
+}
+
+// System that prints remaining expiry time
+void PrintExpire(ecs_iter_t *it) {
+    Timeout *t = ecs_field(it, Timeout, 1);
+
+    for (int i = 0; i < it->count; i ++) {
+        printf("PrintExpire: %s has %.2f seconds left\n", ecs_get_name(
+            it->world, it->entities[i]), t[i].value);
+    }
+}
+
+// Observer that triggers when the component is actually removed
+void Expired(ecs_iter_t *it) {
+    for (int i = 0; i < it->count; i ++) {
+        printf("Expired: %s actually deleted\n", ecs_get_name(
+            it->world, it->entities[i]));
+    }
+}
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *world = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT(world, Timeout);
+    ECS_SYSTEM(world, Expire, EcsOnUpdate, Timeout);
+    ECS_SYSTEM(world, PrintExpire, EcsOnUpdate, [in] Timeout);
+    ECS_OBSERVER(world, Expired, EcsOnRemove, Timeout);
+
+    // Create entity that expires after 3 seconds
+    ecs_entity_t e = ecs_set_name(world, 0, "MyEntity");
+    ecs_set(world, e, Timeout, { 3.0 });
+    
+    ecs_set_target_fps(world, 1);
+
+    while ( ecs_progress(world, 0)) {
+        // If entity is no longer alive, exit
+        if (!ecs_is_alive(world, e)) {
+            break;
+        }
+
+        printf("Tick...\n");
+    }
+
+    // Output:
+    //  PrintExpire: MyEntity has 2.00 seconds left
+    //  Tick...
+    //  PrintExpire: MyEntity has 0.98 seconds left
+    //  Tick...
+    //  Expire: MyEntity deleted!
+    //  PrintExpire: MyEntity has -0.02 seconds left
+    //  Expired: MyEntity actually deleted
+
+    return ecs_fini(world);
+}