PoC for spawning entities with components and querying them

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "lyra-engine"]
+	path = lyra-engine
+	url = git@git.seanomik.net:SeanOMik/lyra-engine.git

Cargo.lock

@@ -67,6 +67,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "atomic_refcell"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41e67cd8309bbd06cd603a9e693a784ac2e5d1e955f11286e355089fcab3047c"
+
 [[package]]
 name = "autocfg"
 version = "1.2.0"
@@ -655,6 +661,12 @@ dependencies = [
  "stable_deref_trait",
 ]
 
+[[package]]
+name = "glam"
+version = "0.24.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5418c17512bdf42730f9032c74e1ae39afc408745ebb2acf72fbc4691c17945"
+
 [[package]]
 name = "hashbrown"
 version = "0.13.2"
@@ -854,6 +866,36 @@ version = "0.4.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
 
+[[package]]
+name = "lyra-ecs"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "atomic_refcell",
+ "lyra-ecs-derive",
+ "lyra-math",
+ "paste",
+ "rand",
+ "thiserror",
+ "tracing",
+]
+
+[[package]]
+name = "lyra-ecs-derive"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "lyra-math"
+version = "0.1.0"
+dependencies = [
+ "glam",
+]
+
 [[package]]
 name = "mach"
 version = "0.3.2"
@@ -2228,6 +2270,7 @@ name = "wittest"
 version = "0.1.0"
 dependencies = [
  "async-trait",
+ "lyra-ecs",
  "tokio",
  "wasmtime",
  "wasmtime-wasi",

Cargo.toml

@@ -11,3 +11,4 @@ async-trait = "0.1.80"
 tokio = { version = "1.37.0", features = ["full"] }
 wasmtime = "19.0.2"
 wasmtime-wasi = "19.0.2"
+lyra-ecs = { path = "./lyra-engine/lyra-ecs" }

lyra-engine

@@ -0,0 +1 @@
+Subproject commit 60ec62c55828a4ea273a10e5614e7cc589b005cf

src/main.rs

@@ -1,6 +1,25 @@
+use std::alloc::Layout;
+use std::any::TypeId;
+use std::mem;
+use std::ptr::NonNull;
+
 use async_trait::async_trait;
+use component::witguest::{ecs_world, math};
+use ecs::query::dynamic::QueryDynamicType;
+use lyra_ecs::{Component, World};
+
+use lyra_ecs as ecs;
+
+use lyra_engine::ecs::component::witguest::ecs_world::WasmTypeId;
 use wasmtime_wasi::WasiView;
 
+#[allow(unused_imports)]
+pub(crate) mod lyra_engine {
+    pub(crate) mod ecs {
+        pub use super::super::*;
+    }
+}
+
 wasmtime::component::bindgen!({
     world: "example",
     path: "witguest/wit/world.wit",
@@ -8,8 +27,50 @@ wasmtime::component::bindgen!({
     async: true,
 });
 
-struct Imports {
+impl WasmTypeId {
+    pub fn of<T: 'static>() -> Self {
+        Self {
+            inner: unsafe { mem::transmute(TypeId::of::<T>()) },
+        }
+    }
+}
 
+impl Into<ecs::DynTypeId> for WasmTypeId {
+    fn into(self) -> ecs::DynTypeId {
+        // SAFETY: the memory layout of (u64, u64) is the same as u128
+        ecs::DynTypeId::Unknown(unsafe { mem::transmute(self.inner) })
+    }
+}
+
+impl Into<ecs::ComponentInfo> for ecs_world::ComponentInfo {
+    fn into(self) -> ecs::ComponentInfo {
+        ecs::ComponentInfo::new_unknown(
+            None,
+            self.type_id,
+            Layout::from_size_align(self.size as _, self.alignment as _).unwrap(),
+        )
+    }
+}
+
+impl From<ecs::Entity> for ecs_world::Entity {
+    fn from(value: ecs::Entity) -> Self {
+        Self {
+            id: ecs_world::EntityId { id: value.id().0 },
+            generation: value.generation(),
+        }
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Clone, Copy, PartialEq, Component)]
+struct Vec3 {
+    x: f32,
+    y: f32,
+    z: f32,
+}
+
+struct Imports {
+    world: lyra_ecs::World,
 }
 
 impl WasiView for Imports {
@@ -24,12 +85,68 @@ impl WasiView for Imports {
 
 #[async_trait]
 impl ExampleImports for Imports {
-    async fn host_test(&mut self,) ->  wasmtime::Result<()> {
+    async fn host_print(&mut self, msg: String) -> wasmtime::Result<()> {
-        println!("This is the host saying hi from the guest!");
+        println!("{}", msg);
         Ok(())
     }
 }
 
+impl math::Host for Imports {}
+
+#[async_trait]
+impl ecs_world::Host for Imports {
+    async fn spawn(
+        &mut self,
+        mut components: Vec<u8>,
+        infos: Vec<ecs_world::ComponentInfo>,
+    ) -> wasmtime::Result<ecs_world::Entity> {
+        // add the components in the tightly packed `components` buffer into the dynamic bundle
+        let mut bundle = ecs::DynamicBundle::new();
+        let mut offset = 0;
+        for info in infos {
+            // SAFETY: The components are tightly packed, adding the offset to the pointer will
+            // get the next component in the buffer.
+            let data_ptr = unsafe { NonNull::new_unchecked(components.as_mut_ptr().add(offset)) };
+            bundle.push_unknown(data_ptr, info.into());
+
+            offset += info.size as usize;
+        }
+
+        let en = self.world.spawn(bundle);
+        Ok(en.into())
+    }
+
+    async fn view(&mut self, infos: Vec<ecs_world::ComponentInfo>) -> wasmtime::Result<Vec<u8>> {
+        // Create a dynamic view for querying for the components
+        let mut view = self.world.dynamic_view();
+        for info in infos.clone() {
+            view.push(QueryDynamicType::from_info(info.into()));
+        }
+
+        // allocate the row of components
+        let total_len = infos.iter().map(|i| i.size as usize).sum();
+        let mut components = Vec::with_capacity(total_len);
+
+        // copy each row of the query into the set of components. could get pretty big, but its a PoC so :shrug:
+        for row in view.into_iter() {
+            let first = row.iter().next().unwrap();
+
+            let mut comp = Vec::<u8>::with_capacity(first.info.layout().size());
+            unsafe {
+                std::ptr::copy_nonoverlapping(
+                    first.ptr.as_ptr(),
+                    comp.as_mut_ptr(),
+                    first.info.layout().size(),
+                );
+                comp.set_len(first.info.layout().size());
+            }
+            components.extend(comp.into_iter());
+        }
+
+        Ok(components)
+    }
+}
+
 #[tokio::main]
 async fn main() -> wasmtime::Result<()> {
     // Instantiate the engine and store
@@ -37,22 +154,29 @@ async fn main() -> wasmtime::Result<()> {
     config.async_support(true);
 
     let engine = wasmtime::Engine::new(&config)?;
-    let mut store = wasmtime::Store::new(&engine, Imports {});
-
-    // Load the component from disk
-    let bytes = std::fs::read("target/wasm32-wasi/debug/witguest.wasm")?;
-    let component = wasmtime::component::Component::new(&engine, bytes)?;
 
     // Configure the linker
     let mut linker = wasmtime::component::Linker::new(&engine);
     wasmtime_wasi::bindings::Imports::add_to_linker(&mut linker, |s| s)?;
     Example::add_to_linker(&mut linker, |s| s)?;
 
+    // memory per instance
+    let mut store = wasmtime::Store::new(
+        &engine,
+        Imports {
+            world: World::new(),
+        },
+    );
+
+    // Load the component from disk
+    let bytes = std::fs::read("target/wasm32-wasi/debug/witguest.wasm")?;
+    let component = wasmtime::component::Component::new(&engine, bytes)?;
+
     // Instantiate the component
     println!("creating example");
     let (example, _instance) = Example::instantiate_async(&mut store, &component, &linker).await?;
-    let result = example.call_hello_world(&mut store).await?;
+    let result = example.call_on_init(&mut store).await?.unwrap();
-    println!("Guest says: {}", result);
+    println!("Guest returned: {}", result);
 
     Ok(())
 }

witguest/src/bindings.rs

@@ -1,29 +1,32 @@
 // Generated by `wit-bindgen` 0.18.0. DO NOT EDIT!
 #[allow(unused_unsafe, clippy::all)]
-pub fn host_test(){
+pub fn host_print(msg: &str,){
   
   #[allow(unused_imports)]
   use wit_bindgen::rt::{alloc, vec::Vec, string::String};
   unsafe {
+    let vec0 = msg;
+    let ptr0 = vec0.as_ptr() as i32;
+    let len0 = vec0.len() as i32;
     
     #[cfg(target_arch = "wasm32")]
     #[link(wasm_import_module = "$root")]
     extern "C" {
-      #[link_name = "host-test"]
+      #[link_name = "host-print"]
-      fn wit_import();
+      fn wit_import(_: i32, _: i32, );
     }
     
     #[cfg(not(target_arch = "wasm32"))]
-    fn wit_import(){ unreachable!() }
+    fn wit_import(_: i32, _: i32, ){ unreachable!() }
-    wit_import();
+    wit_import(ptr0, len0);
   }
 }
 const _: () = {
   
   #[doc(hidden)]
-  #[export_name = "hello-world"]
+  #[export_name = "on-init"]
   #[allow(non_snake_case)]
-  unsafe extern "C" fn __export_hello_world() -> i32 {
+  unsafe extern "C" fn __export_on_init() -> i32 {
     #[allow(unused_imports)]
     use wit_bindgen::rt::{alloc, vec::Vec, string::String};
     
@@ -41,44 +44,171 @@ const _: () = {
     #[cfg(target_arch="wasm32")]
     wit_bindgen::rt::run_ctors_once();
     
-    let result0 = <_GuestImpl as Guest>::hello_world();
+    let result0 = <_GuestImpl as Guest>::on_init();
     let ptr1 = _RET_AREA.0.as_mut_ptr() as i32;
-    let vec2 = (result0.into_bytes()).into_boxed_slice();
+    match result0 {
-    let ptr2 = vec2.as_ptr() as i32;
+      Ok(e) => { {
-    let len2 = vec2.len() as i32;
+        *((ptr1 + 0) as *mut u8) = (0i32) as u8;
-    ::core::mem::forget(vec2);
+        *((ptr1 + 1) as *mut u8) = (wit_bindgen::rt::as_i32(e)) as u8;
-    *((ptr1 + 4) as *mut i32) = len2;
+      } },
-    *((ptr1 + 0) as *mut i32) = ptr2;
+      Err(_) => { {
-    ptr1
+        *((ptr1 + 0) as *mut u8) = (1i32) as u8;
+      } },
+    };ptr1
   }
-  
-  const _: () = {
-    #[doc(hidden)]
-    #[export_name = "cabi_post_hello-world"]
-    #[allow(non_snake_case)]
-    unsafe extern "C" fn __post_return_hello_world(arg0: i32,) {
-      let l0 = *((arg0 + 0) as *const i32);
-      let l1 = *((arg0 + 4) as *const i32);
-      wit_bindgen::rt::dealloc(l0, (l1) as usize, 1);
-    }
-  };
 };
 use super::Component as _GuestImpl;
 pub trait Guest {
-  fn hello_world() -> wit_bindgen::rt::string::String;
+  fn on_init() -> Result<u8,()>;
 }
 
 #[allow(unused_imports)]
 use wit_bindgen::rt::{alloc, vec::Vec, string::String};
 
-#[repr(align(4))]
+#[repr(align(1))]
-struct _RetArea([u8; 8]);
+struct _RetArea([u8; 2]);
-static mut _RET_AREA: _RetArea = _RetArea([0; 8]);
+static mut _RET_AREA: _RetArea = _RetArea([0; 2]);
+pub mod component {
+  pub mod witguest {
+    
+    #[allow(clippy::all)]
+    pub mod math {
+      #[used]
+      #[doc(hidden)]
+      #[cfg(target_arch = "wasm32")]
+      static __FORCE_SECTION_REF: fn() = super::super::super::__link_section;
+      
+    }
+    
+    
+    #[allow(clippy::all)]
+    pub mod ecs_world {
+      #[used]
+      #[doc(hidden)]
+      #[cfg(target_arch = "wasm32")]
+      static __FORCE_SECTION_REF: fn() = super::super::super::__link_section;
+      /// use math.{vec3};
+      #[repr(C)]
+      #[derive(Clone, Copy)]
+      pub struct EntityId {
+        pub id: u64,
+      }
+      impl ::core::fmt::Debug for EntityId {
+        fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+          f.debug_struct("EntityId").field("id", &self.id).finish()
+        }
+      }
+      #[repr(C)]
+      #[derive(Clone, Copy)]
+      pub struct Entity {
+        pub id: EntityId,
+        pub generation: u64,
+      }
+      impl ::core::fmt::Debug for Entity {
+        fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+          f.debug_struct("Entity").field("id", &self.id).field("generation", &self.generation).finish()
+        }
+      }
+      #[repr(C)]
+      #[derive(Clone, Copy)]
+      pub struct WasmTypeId {
+        pub inner: (u64,u64,),
+      }
+      impl ::core::fmt::Debug for WasmTypeId {
+        fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+          f.debug_struct("WasmTypeId").field("inner", &self.inner).finish()
+        }
+      }
+      #[repr(C)]
+      #[derive(Clone, Copy)]
+      pub struct ComponentInfo {
+        pub size: u64,
+        pub alignment: u64,
+        pub type_id: WasmTypeId,
+      }
+      impl ::core::fmt::Debug for ComponentInfo {
+        fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+          f.debug_struct("ComponentInfo").field("size", &self.size).field("alignment", &self.alignment).field("type-id", &self.type_id).finish()
+        }
+      }
+      #[allow(unused_unsafe, clippy::all)]
+      /// expects components to be tightly packed in the same order of component-infos
+      pub fn spawn(components: &[u8],component_infos: &[ComponentInfo],) -> Entity{
+        
+        #[allow(unused_imports)]
+        use wit_bindgen::rt::{alloc, vec::Vec, string::String};
+        unsafe {
+          
+          #[repr(align(8))]
+          struct RetArea([u8; 16]);
+          let mut ret_area = ::core::mem::MaybeUninit::<RetArea>::uninit();
+          let vec0 = components;
+          let ptr0 = vec0.as_ptr() as i32;
+          let len0 = vec0.len() as i32;
+          let vec1 = component_infos;
+          let ptr1 = vec1.as_ptr() as i32;
+          let len1 = vec1.len() as i32;
+          let ptr2 = ret_area.as_mut_ptr() as i32;
+          #[cfg(target_arch = "wasm32")]
+          #[link(wasm_import_module = "component:witguest/ecs-world")]
+          extern "C" {
+            #[link_name = "spawn"]
+            fn wit_import(_: i32, _: i32, _: i32, _: i32, _: i32, );
+          }
+          
+          #[cfg(not(target_arch = "wasm32"))]
+          fn wit_import(_: i32, _: i32, _: i32, _: i32, _: i32, ){ unreachable!() }
+          wit_import(ptr0, len0, ptr1, len1, ptr2);
+          let l3 = *((ptr2 + 0) as *const i64);
+          let l4 = *((ptr2 + 8) as *const i64);
+          Entity{
+            id: EntityId{
+              id: l3 as u64,
+            },
+            generation: l4 as u64,
+          }
+        }
+      }
+      #[allow(unused_unsafe, clippy::all)]
+      pub fn view(component_infos: &[ComponentInfo],) -> wit_bindgen::rt::vec::Vec::<u8>{
+        
+        #[allow(unused_imports)]
+        use wit_bindgen::rt::{alloc, vec::Vec, string::String};
+        unsafe {
+          
+          #[repr(align(4))]
+          struct RetArea([u8; 8]);
+          let mut ret_area = ::core::mem::MaybeUninit::<RetArea>::uninit();
+          let vec0 = component_infos;
+          let ptr0 = vec0.as_ptr() as i32;
+          let len0 = vec0.len() as i32;
+          let ptr1 = ret_area.as_mut_ptr() as i32;
+          #[cfg(target_arch = "wasm32")]
+          #[link(wasm_import_module = "component:witguest/ecs-world")]
+          extern "C" {
+            #[link_name = "view"]
+            fn wit_import(_: i32, _: i32, _: i32, );
+          }
+          
+          #[cfg(not(target_arch = "wasm32"))]
+          fn wit_import(_: i32, _: i32, _: i32, ){ unreachable!() }
+          wit_import(ptr0, len0, ptr1);
+          let l2 = *((ptr1 + 0) as *const i32);
+          let l3 = *((ptr1 + 4) as *const i32);
+          let len4 = l3 as usize;
+          Vec::from_raw_parts(l2 as *mut _, len4, len4)
+        }
+      }
+      
+    }
+    
+  }
+}
 
 #[cfg(target_arch = "wasm32")]
 #[link_section = "component-type:example"]
 #[doc(hidden)]
-pub static __WIT_BINDGEN_COMPONENT_TYPE: [u8; 201] = [0, 97, 115, 109, 13, 0, 1, 0, 0, 25, 22, 119, 105, 116, 45, 99, 111, 109, 112, 111, 110, 101, 110, 116, 45, 101, 110, 99, 111, 100, 105, 110, 103, 4, 0, 7, 77, 1, 65, 2, 1, 65, 4, 1, 64, 0, 1, 0, 3, 0, 9, 104, 111, 115, 116, 45, 116, 101, 115, 116, 1, 0, 1, 64, 0, 0, 115, 4, 0, 11, 104, 101, 108, 108, 111, 45, 119, 111, 114, 108, 100, 1, 1, 4, 1, 26, 99, 111, 109, 112, 111, 110, 101, 110, 116, 58, 119, 105, 116, 103, 117, 101, 115, 116, 47, 101, 120, 97, 109, 112, 108, 101, 4, 0, 11, 13, 1, 0, 7, 101, 120, 97, 109, 112, 108, 101, 3, 0, 0, 0, 70, 9, 112, 114, 111, 100, 117, 99, 101, 114, 115, 1, 12, 112, 114, 111, 99, 101, 115, 115, 101, 100, 45, 98, 121, 2, 13, 119, 105, 116, 45, 99, 111, 109, 112, 111, 110, 101, 110, 116, 6, 48, 46, 50, 49, 46, 48, 16, 119, 105, 116, 45, 98, 105, 110, 100, 103, 101, 110, 45, 114, 117, 115, 116, 6, 48, 46, 49, 56, 46, 48];
+pub static __WIT_BINDGEN_COMPONENT_TYPE: [u8; 514] = [0, 97, 115, 109, 13, 0, 1, 0, 0, 25, 22, 119, 105, 116, 45, 99, 111, 109, 112, 111, 110, 101, 110, 116, 45, 101, 110, 99, 111, 100, 105, 110, 103, 4, 0, 7, 133, 3, 1, 65, 2, 1, 65, 9, 1, 66, 2, 1, 114, 3, 1, 120, 118, 1, 121, 118, 1, 122, 118, 4, 0, 4, 118, 101, 99, 51, 3, 0, 0, 3, 1, 23, 99, 111, 109, 112, 111, 110, 101, 110, 116, 58, 119, 105, 116, 103, 117, 101, 115, 116, 47, 109, 97, 116, 104, 5, 0, 1, 66, 15, 1, 114, 1, 2, 105, 100, 119, 4, 0, 9, 101, 110, 116, 105, 116, 121, 45, 105, 100, 3, 0, 0, 1, 114, 2, 2, 105, 100, 1, 10, 103, 101, 110, 101, 114, 97, 116, 105, 111, 110, 119, 4, 0, 6, 101, 110, 116, 105, 116, 121, 3, 0, 2, 1, 111, 2, 119, 119, 1, 114, 1, 5, 105, 110, 110, 101, 114, 4, 4, 0, 12, 119, 97, 115, 109, 45, 116, 121, 112, 101, 45, 105, 100, 3, 0, 5, 1, 114, 3, 4, 115, 105, 122, 101, 119, 9, 97, 108, 105, 103, 110, 109, 101, 110, 116, 119, 7, 116, 121, 112, 101, 45, 105, 100, 6, 4, 0, 14, 99, 111, 109, 112, 111, 110, 101, 110, 116, 45, 105, 110, 102, 111, 3, 0, 7, 1, 112, 125, 1, 112, 8, 1, 64, 2, 10, 99, 111, 109, 112, 111, 110, 101, 110, 116, 115, 9, 15, 99, 111, 109, 112, 111, 110, 101, 110, 116, 45, 105, 110, 102, 111, 115, 10, 0, 3, 4, 0, 5, 115, 112, 97, 119, 110, 1, 11, 1, 64, 1, 15, 99, 111, 109, 112, 111, 110, 101, 110, 116, 45, 105, 110, 102, 111, 115, 10, 0, 9, 4, 0, 4, 118, 105, 101, 119, 1, 12, 3, 1, 28, 99, 111, 109, 112, 111, 110, 101, 110, 116, 58, 119, 105, 116, 103, 117, 101, 115, 116, 47, 101, 99, 115, 45, 119, 111, 114, 108, 100, 5, 1, 1, 64, 1, 3, 109, 115, 103, 115, 1, 0, 3, 0, 10, 104, 111, 115, 116, 45, 112, 114, 105, 110, 116, 1, 2, 1, 106, 1, 125, 0, 1, 64, 0, 0, 3, 4, 0, 7, 111, 110, 45, 105, 110, 105, 116, 1, 4, 4, 1, 26, 99, 111, 109, 112, 111, 110, 101, 110, 116, 58, 119, 105, 116, 103, 117, 101, 115, 116, 47, 101, 120, 97, 109, 112, 108, 101, 4, 0, 11, 13, 1, 0, 7, 101, 120, 97, 109, 112, 108, 101, 3, 0, 0, 0, 70, 9, 112, 114, 111, 100, 117, 99, 101, 114, 115, 1, 12, 112, 114, 111, 99, 101, 115, 115, 101, 100, 45, 98, 121, 2, 13, 119, 105, 116, 45, 99, 111, 109, 112, 111, 110, 101, 110, 116, 6, 48, 46, 50, 49, 46, 48, 16, 119, 105, 116, 45, 98, 105, 110, 100, 103, 101, 110, 45, 114, 117, 115, 116, 6, 48, 46, 49, 56, 46, 48];
 
 #[inline(never)]
 #[doc(hidden)]

witguest/src/lib.rs

@@ -1,13 +1,63 @@
+#[allow(warnings)]
 mod bindings;
 
-use bindings::Guest;
+use bindings::{component::witguest::ecs_world::{self, ComponentInfo, WasmTypeId}, Guest};
+
+use std::{alloc::Layout, any::TypeId, mem};
+
+impl WasmTypeId {
+    pub fn of<T: 'static>() -> Self {
+        Self {
+            inner: unsafe { mem::transmute(TypeId::of::<T>()) }
+        }
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Clone, Copy, PartialEq)]
+struct Vec3 {
+    x: f32,
+    y: f32,
+    z: f32,
+}
+
+impl Vec3 {
+    pub fn new(x: f32, y: f32, z: f32) -> Self {
+        Self {
+            x, y, z
+        }
+    }
+
+    pub fn component_info() -> ComponentInfo {
+        let layout = Layout::new::<Vec3>();
+        ComponentInfo {
+            size: layout.size() as u64,
+            alignment: layout.align() as u64,
+            type_id: WasmTypeId::of::<Vec3>(),
+        }
+    }
+}
 
 struct Component;
 
 impl Guest for Component {
-    /// Say hello!
+    fn on_init() -> Result<u8, ()> {
-    fn hello_world() -> String {
+        let comps = &mut [Vec3::new(7.0, 30.0, 18.0),];
-        bindings::host_test();
+        let info = &[Vec3::component_info()];
-        "Hello, World!".to_string()
+
+        // no fucking clue if this will work, but lets try and it see
+        let comps = comps.as_mut_ptr().cast::<u8>();
+        let comps = unsafe { Vec::from_raw_parts(comps, mem::size_of::<Vec3>(), 1) };
+
+        let en = ecs_world::spawn(&comps, info);
+
+        bindings::host_print(&format!("Spawned entity: {}", en.id.id));
+
+        let mut buffer = ecs_world::view(&[Vec3::component_info()]);
+        bindings::host_print(&format!("Retrieved vec3 of {} bytes long", buffer.len()));
+        let fetched_vec = unsafe { std::ptr::read(buffer.as_mut_ptr().cast::<Vec3>()) };
+        bindings::host_print(&format!("Retrieved vec3: {:?}", fetched_vec));
+
+        Ok(0)
     }
 }

witguest/wit/world.wit

@@ -1,7 +1,45 @@
 package component:witguest;
 
+interface math {
+    record vec3 {
+        x: f32,
+        y: f32,
+        z: f32,
+    }
+}
+
+interface ecs-world {
+    //use math.{vec3};
+
+    record entity-id {
+        id: u64,
+    }
+
+    record entity {
+        id: entity-id,
+        generation: u64,
+    }
+
+    record wasm-type-id {
+        inner: tuple<u64, u64>,
+    }
+
+    record component-info {
+        size: u64,
+        alignment: u64,
+        type-id: wasm-type-id, // a u128
+    }
+
+    // expects components to be tightly packed in the same order of component-infos
+    spawn: func(components: list<u8>, component-infos: list<component-info>) -> entity;
+    view: func(component-infos: list<component-info>) -> list<u8>;
+}
+
 /// An example world for the component to target.
 world example {
-    import host-test: func();
+    import math;
-    export hello-world: func() -> string;
+    import ecs-world;
+
+    import host-print: func(msg: string);
+    export on-init: func() -> result<u8>;
 }