#55 add periodic system C example, fix issue in flecs.hpp

examples/c/35_periodic_system/include/periodic_system.h

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

examples/c/35_periodic_system/include/periodic_system/bake_config.h

@@ -0,0 +1,44 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * 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 PERIODIC_SYSTEM_BAKE_CONFIG_H
+#define PERIODIC_SYSTEM_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+/* Headers of private dependencies */
+#ifdef PERIODIC_SYSTEM_IMPL
+/* No dependencies */
+#endif
+
+/* Convenience macro for exporting symbols */
+#ifndef PERIODIC_SYSTEM_STATIC
+  #if PERIODIC_SYSTEM_IMPL && (defined(_MSC_VER) || defined(__MINGW32__))
+    #define PERIODIC_SYSTEM_EXPORT __declspec(dllexport)
+  #elif PERIODIC_SYSTEM_IMPL
+    #define PERIODIC_SYSTEM_EXPORT __attribute__((__visibility__("default")))
+  #elif defined _MSC_VER
+    #define PERIODIC_SYSTEM_EXPORT __declspec(dllimport)
+  #else
+    #define PERIODIC_SYSTEM_EXPORT
+  #endif
+#else
+  #define PERIODIC_SYSTEM_EXPORT
+#endif
+
+#endif
+

examples/c/35_periodic_system/project.json

@@ -0,0 +1,12 @@
+{
+    "id": "periodic_system",
+    "type": "application",
+    "value": {
+        "author": "Jane Doe",
+        "description": "A simple hello world flecs application",
+        "public": false,
+        "use": [
+            "flecs"
+        ]
+    }
+}

examples/c/35_periodic_system/src/main.c

@@ -0,0 +1,69 @@
+#include <periodic_system.h>
+
+/* Component types */
+typedef struct Vector2D {
+    float x;
+    float y;
+} Vector2D;
+
+typedef Vector2D Position;
+typedef Vector2D Velocity;
+
+void Move(ecs_rows_t *rows) {
+    ECS_COLUMN(rows, Position, p, 1);
+    ECS_COLUMN(rows, Velocity, v, 2);
+
+    for (int i = 0; i < rows->count; i ++) {
+        p[i].x += v[i].x;
+        p[i].y += v[i].y;
+    }
+}
+
+void PrintPosition(ecs_rows_t *rows) {
+    ECS_COLUMN(rows, Position, p, 1);
+
+    for (int i = 0; i < rows->count; i ++) {
+        printf("%s position = {.x = %f, .y = %f}\n",
+            ecs_get_id(rows->world, rows->entities[i]),
+            p[i].x, p[i].y);
+    }
+}
+
+int main(int argc, char *argv[]) {
+    /* Create the world, pass arguments for overriding the number of threads,fps
+     * or for starting the admin dashboard (see flecs.h for details). */
+    ecs_world_t *world = ecs_init_w_args(argc, argv);
+
+    /* Register components */
+    ECS_COMPONENT(world, Position);
+    ECS_COMPONENT(world, Velocity);
+
+    /* Define a system called Move that is executed every frame, and subscribes
+     * for the 'Position' and 'Velocity' components */
+    ECS_SYSTEM(world, Move, EcsOnUpdate, Position, Velocity);
+
+    /* Create a system that prints the position of an entity once per second */
+    ECS_SYSTEM(world, PrintPosition, EcsOnUpdate, Position);
+    ecs_set_period(world, PrintPosition, 1.0);
+
+    /* Create an entity with Position and Velocity. Creating an entity with the
+     * ECS_ENTITY macro is an easy way to create entities with multiple
+     * components. Additionally, entities created with this macro can be looked
+     * up by their name ('MyEntity'). */
+    ECS_ENTITY(world, MyEntity, Position, Velocity);
+
+    /* Initialize values for the entity */
+    ecs_set(world, MyEntity, Position, {0, 0});
+    ecs_set(world, MyEntity, Velocity, {1, 1});
+
+    /* Run at 60FPS */
+    ecs_set_target_fps(world, 60);
+
+    printf("Application move_system is running, press CTRL-C to exit...\n");
+
+    /* Run systems */
+    while ( ecs_progress(world, 0));
+
+    /* Cleanup */
+    return ecs_fini(world);
+}

include/flecs/flecs.hpp

@@ -894,7 +894,8 @@ class component : public entity {
             component_base<T>::s_type, 
             component_base<T>::s_name);    
 
-        entity(world, component_base<T>::s_entity);
+        m_id = component_base<T>::s_entity;
+        m_world = world.c_ptr();
     }
 };
 
@@ -1188,7 +1189,8 @@ class system final : public entity {
 public:
     system(const world& world, const char *name = nullptr)
         : m_kind(static_cast<EcsSystemKind>(OnUpdate))
-        , m_name(name) 
+        , m_name(name)
+        , m_period(0.0)
         , m_on_demand(false)
         , m_hidden(false) { 
             m_world = world.c_ptr();
@@ -1204,6 +1206,11 @@ class system final : public entity {
         return *this;
     }
 
+    system& period(float period) {
+        m_period = period;
+        return *this;
+    }
+
     system& on_demand() {
         m_on_demand = true;
         return *this;
@@ -1304,6 +1311,10 @@ class system final : public entity {
 
         ecs_set_system_context(m_world, e, ctx);
 
+        if (m_period) {
+            ecs_set_period(m_world, e, m_period);
+        }
+
         m_id = e;
 
         return *this;
@@ -1334,6 +1345,7 @@ class system final : public entity {
     EcsSystemKind m_kind;
     const char *m_name;
     const char *m_signature = nullptr;
+    float m_period;
     bool m_on_demand;
     bool m_hidden;
 };