Properly link flecs library

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

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

engine/libs/flecs/examples/c/systems/sync_point/include/sync_point/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 SYNC_POINT_BAKE_CONFIG_H
+#define SYNC_POINT_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

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

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

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

@@ -0,0 +1,121 @@
+#include <sync_point.h>
+#include <stdio.h>
+
+typedef struct {
+    double x, y;
+} Position, Velocity;
+
+// Forward declare components so they can be accessed from systems
+ECS_COMPONENT_DECLARE(Position);
+ECS_COMPONENT_DECLARE(Velocity);
+
+void SetVelocity(ecs_iter_t *it) {
+    for (int i = 0; i < it->count; i ++) {
+        ecs_set(it->world, it->entities[i], Velocity, {1, 2});
+    }
+}
+
+void Move(ecs_iter_t *it) {
+    Position *p = ecs_field(it, Position, 1);
+    const Velocity *v = ecs_field(it, const Velocity, 2);
+
+    for (int i = 0; i < it->count; i ++) {
+        p[i].x += v[i].x;
+        p[i].y += v[i].y;
+    }
+}
+
+void PrintPosition(ecs_iter_t *it) {
+    const Position *p = ecs_field(it, const Position, 1);
+
+    for (int i = 0; i < it->count; i ++) {
+        printf("%s: {%f, %f}\n", ecs_get_name(it->world, it->entities[i]), 
+            p[i].x, p[i].y);
+    }
+}
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT_DEFINE(ecs, Position);
+    ECS_COMPONENT_DEFINE(ecs, Velocity);
+
+    // System that sets velocity using set<T> for entities with Position.
+    // While systems are progressing, operations like set<T> are deferred until
+    // it is safe to merge. By default this merge happens at the end of the
+    // frame, but we can annotate systems to give the scheduler more information
+    // about what it's doing, which allows it to insert sync points earlier.
+    // 
+    // The parentheses after Velocity indicate that the component is not used
+    // to match entities, while [out] indicates that it is written. A subsequent
+    // system that accesses the component will cause the scheduler to insert a
+    // sync point.
+    //
+    // Note that sync points are never necessary/inserted for systems that write
+    // components provided by their signature, as these writes directly happen
+    // in the ECS storage and are never deferred.
+    //
+    // The [none] annotation for Position tells the scheduler that while we 
+    // want to match entities with Position, we're not interested in reading or 
+    // writing the component value.
+    ECS_SYSTEM(ecs, SetVelocity, EcsOnUpdate, [none] Position, [out] Velocity());
+
+    // This system reads Velocity, which causes the insertion of a sync point.
+    ECS_SYSTEM(ecs, Move, EcsOnUpdate, Position, [in] Velocity);
+
+    // Print resulting Position
+    ECS_SYSTEM(ecs, PrintPosition, EcsPostUpdate, [in] Position);
+
+    // Create a few test entities for a Position, Velocity query
+    ecs_entity_t e1 = ecs_new_entity(ecs, "e1");
+    ecs_set(ecs, e1, Position, {10, 20});
+    ecs_set(ecs, e1, Velocity, {1, 2});
+
+    ecs_entity_t e2 = ecs_new_entity(ecs, "e2");
+    ecs_set(ecs, e2, Position, {10, 20});
+    ecs_set(ecs, e2, Velocity, {3, 4});
+
+    // Run systems. Debug logging enables us to see the generated schedule
+    ecs_log_set_level(1);
+    ecs_progress(ecs, 0.0f);
+    ecs_log_set_level(-1); // Restore so we don't get world cleanup logs
+
+    // Output:
+    //  info: pipeline rebuild:
+    //  info: | schedule: threading: 0, staging: 1:
+    //  info: | | system SetVelocity
+    //  info: | | merge
+    //  info: | schedule: threading: 0, staging: 1:
+    //  info: | | system Move
+    //  info: | | system PrintPosition
+    //  info: | | merge
+    //  e1: {11.000000, 22.000000}
+    //  e2: {11.000000, 22.000000}
+    //
+    // The "merge" lines indicate sync points.
+    //
+    // Removing the '[out] Velocity()' annotation from the system will remove
+    // the first sync point from the schedule.
+    //
+    // To create the same system with ecs_system_init, do:
+    //  ecs_system_init(ecs, &(ecs_system_desc_t){
+    //      .query.filter.terms = {
+    //          { 
+    //              .id = ecs_id(Position), 
+    //              .inout = EcsInOutNone 
+    //          },
+    //          { 
+    //              .id = ecs_id(Velocity), 
+    //              .inout = EcsOut, 
+    //              .src.flags = EcsIsEntity 
+    //          }
+    //      },
+    //      .entity = {
+    //          .name = "SetVelocity",
+    //          .add = {ecs_dependson(EcsOnUpdate)}
+    //      },
+    //      .callback = SetVelocity
+    //  });
+
+    return ecs_fini(ecs);
+}