Properly link flecs library

engine/libs/flecs/examples/cpp/systems/sync_point_delete/include/sync_point_delete.h

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

engine/libs/flecs/examples/cpp/systems/sync_point_delete/include/sync_point_delete/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_DELETE_BAKE_CONFIG_H
+#define SYNC_POINT_DELETE_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/cpp/systems/sync_point_delete/project.json

@@ -0,0 +1,11 @@
+{
+    "id": "sync_point_delete",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "language": "c++",
+        "public": false
+    }
+}

engine/libs/flecs/examples/cpp/systems/sync_point_delete/src/main.cpp

@@ -0,0 +1,97 @@
+#include <sync_point_delete.h>
+#include <iostream>
+
+struct Position { 
+    double x, y;
+};
+
+struct Velocity { 
+    double x, y;
+};
+
+int main(int, char *[]) {
+    flecs::world ecs;
+
+    // This example shows how to annotate systems that delete entities, in a way
+    // that allows the scheduler to correctly insert sync points. See the
+    // sync_point example for more details on sync points.
+    //
+    // While annotating a system for a delete operation follows the same 
+    // design as other operations, one key difference is that a system often 
+    // does not know which components a to be deleted entity has. This makes it
+    // impossible to annotate the system in advance for specific components.
+    //
+    // To ensure the scheduler is still able to insert the correct sync points,
+    // a system can use a wildcard to indicate that any component could be
+    // modified by the system, which forces the scheduler to insert a sync.
+
+    // Basic move system.
+    ecs.system<Position, const Velocity>("Move")
+        .each([](Position& p, const Velocity& v) {
+            p.x += v.x;
+            p.y += v.y;
+        });
+
+    // Delete entities when p.x >= 3. Add wildcard annotation to indicate any
+    // component could be written by the system. Position itself is added as 
+    // const, since inside the system we're only reading it.
+    ecs.system<const Position>("DeleteEntity")
+        .write(flecs::Wildcard)
+        .each([](flecs::entity e, const Position& p) {
+            if (p.x >= 3) {
+                std::cout << "Delete entity " << e.name() << "\n";
+                e.destruct();
+            }
+        });
+
+    // Print resulting Position. Note that this system will never print entities
+    // that have been deleted by the previous system.
+    ecs.system<const Position>("PrintPosition")
+        .each([](flecs::entity e, const Position& p) {
+            std::cout << e.name() << ": {" << p.x << ", " << p.y << "}\n";
+        });
+
+    // Create a few test entities for a Position, Velocity query
+    ecs.entity("e1")
+        .set<Position>({0, 0})
+        .set<Velocity>({1, 2});
+
+    ecs.entity("e2")
+        .set<Position>({1, 2})
+        .set<Velocity>({1, 2});
+
+    // Run systems. Debug logging enables us to see the generated schedule
+    flecs::log::set_level(1);
+    while (ecs.progress()) {
+        if (!ecs.count<Position>()) {
+            break; // No more entities left with Position
+        }
+    }
+    flecs::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 Move
+    //  info: | | system DeleteEntity
+    //  info: | | merge
+    //  info: | schedule: threading: 0, staging: 1:
+    //  info: | | system PrintPosition
+    //  info: | | merge
+    //  e1: {1, 2}
+    //  e2: {2, 4}
+    //  Delete entity e2
+    //  e1: {2, 4}
+    //  Delete entity e1
+    //  info: system Move deactivated
+    //  info: system DeleteEntity deactivated
+    //  info: system PrintPosition deactivated
+    //
+    // Removing the wildcard annotation from the DeleteEntity system will
+    // remove the first sync point.
+    //
+    // Note how after both entities are deleted, all three systems are 
+    // deactivated. This happens when there are no matching entities for a
+    // system. A deactivated system is not ran by the scheduler, which reduces
+    // overhead.
+}