From 47751e6647ea78316db0aa2d4132697bdd3521a4 Mon Sep 17 00:00:00 2001
From: Indradb <60851042+Indra-db@users.noreply.github.com>
Date: Mon, 4 Mar 2024 16:48:01 +0700
Subject: [PATCH] Init examples w/ hello_world

---
 flecs_ecs/examples/hello_world.rs | 61 +++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 flecs_ecs/examples/hello_world.rs

diff --git a/flecs_ecs/examples/hello_world.rs b/flecs_ecs/examples/hello_world.rs
new file mode 100644
index 00000000..f481a6b7
--- /dev/null
+++ b/flecs_ecs/examples/hello_world.rs
@@ -0,0 +1,61 @@
+use std::ffi::CStr;
+
+use flecs_ecs::core::*;
+use flecs_ecs_derive::Component;
+
+#[derive(Debug, Default, Clone, Component)]
+struct Position {
+    x: f32,
+    y: f32,
+}
+
+#[derive(Default, Clone, Component)]
+struct Velocity {
+    x: f32,
+    y: f32,
+}
+
+#[derive(Default, Clone, Component)]
+struct Eats {}
+#[derive(Default, Clone, Component)]
+struct Apples {}
+
+fn main() {
+    // Create a new world
+    let world = World::new();
+
+    // Register system
+    let _sys = world
+        .system_builder::<(Position, Velocity)>()
+        .on_each_entity(|_entity, (pos, vel)| {
+            pos.x += vel.x;
+            pos.y += vel.y;
+        });
+
+    // Create an entity with name Bob, add Position and food preference
+    let bob = world
+        .new_entity_named(CStr::from_bytes_with_nul(b"Bob\0").unwrap())
+        .set_component(Position { x: 0.0, y: 0.0 })
+        .set_component(Velocity { x: 1.0, y: 2.0 })
+        .add_pair::<Eats, Apples>();
+
+    // Show us what you got
+    println!(
+        "{}'s got [{}]",
+        bob.get_name(),
+        bob.get_archetype().to_string().unwrap()
+    );
+
+    // Run systems twice. Usually this function is called once per frame
+    world.progress();
+    world.progress();
+
+    // See if Bob has moved (he has)
+    let pos = bob.get_component::<Position>();
+    let pos_ref = unsafe { pos.as_ref().unwrap() };
+    println!("Bob's position: {:?}", pos_ref);
+
+    // Output
+    //  Bob's got [Position, Velocity, (Identifier,Name), (Eats,Apples)]
+    //  Bob's position: Position { x: 2.0, y: 4.0 }
+}