Update TODO

TODO.md

@@ -3,23 +3,25 @@
 ## Core
 
 - ~~Add and implement interfaces for systems (ISystem, IUpdatableSystem, etc.)~~
-- Minimize amount of possible null references.
-- TextDataResource providing a convenient wrapper around TOML data files.
-- Add documentation for common classes.
+- ~~Minimize amount of possible null references.~~
+- ~~TextDataResource providing a convenient wrapper around TOML data files.~~
+- ~~Add documentation for common classes.~~
 - ~~Hot reloading of resources.~~
 
 ## I/O
 
-- Use GUIDs and string ID maps for fetching resources instead of string IDs alone.
-- (stretch goal) Make async API for ResourceManager
-- (stretch goal/1.0) Streamed resource loading
-- (stretch goal) Virtual file system
+- ~~Use GUIDs and string ID maps for fetching resources instead of string IDs alone.~~
+- Reimplement unloading.
+- Finalize ResourceManager and ResourceLoader APIs for 1.0.
+- (stretch goal) Streamed resource loading.
+- (stretch goal) Add async API for ResourceManager.
+- (stretch goal) Virtual file system.
 
 ## Serialization
 
 - Serialize attribute.
 - Add automatic serialization of resources through code generation and System.Text.Json.
-- Provide means for fetching key/value configuration (INI? TOML?)
+- ~~Provide means for fetching key/value configuration (INI? TOML?)~~
   - Expose some sort of ConfigFile class for safe key/value configuration fetching.
 
 ## Rendering
@@ -27,7 +29,7 @@
 - ~~API for drawing textured quads~~
 - ~~Camera API~~
 - Arbitrary mesh rendering API.
-- (1.0) Create WebGPU renderer (StandardRenderer)
+- Create WebGPU renderer (StandardRenderer)
 
 ## Audio
 
@@ -38,11 +40,14 @@
 
 - ~~Asset manager~~
 - ~~Separate engine and game into separate projects~~
-- ~~Particle system~~
+- Particle system 2.0
+  - Reduce the size of Particle struct by infering most parameters through lifetime.
+  - Reduce cache misses by utilizing SoA.
+  - SIMD acceleration.
 
 ## SceneGraph module
 
-- ~~Layers (sorting mechanism)~~
+- Layers (sorting mechanism)
 - Full overhaul using Entity Component architecture (not to be mistaken with ECS).
 - Save/load scenes from file