feat: Renderer Trait, enum and builder fn

Fixes #12

examples/hello-world/main.rs

@@ -1,11 +1,19 @@
 use scion::application::Scion;
-use scion::legion::system;
+use scion::legion::{system, Resources, World};
 use scion::utils::time::Time;
 use log::info;
 use scion::utils::window::WindowDimensions;
 use scion::config::scion_config::{ScionConfig, ScionConfigBuilder};
 use scion::config::window_config::{WindowConfig, WindowConfigBuilder};
+use scion::renderer::{RendererType, ScionRenderer};
+use miniquad::Context;
 
+struct T;
+impl ScionRenderer for T{
+    fn draw(&mut self, context: &mut Context, world: &mut World, resource: &mut Resources) {
+        unimplemented!()
+    }
+}
 
 #[system]
 fn time(#[resource] time: &Time) {
@@ -21,5 +29,6 @@ fn main() {
     Scion::app()
         .with_system(time_system())
         .with_system(screen_system())
+        .with_renderer(RendererType::Custom(Box::new(T)))
         .run();
-}
+}

src/application.rs

@@ -6,6 +6,7 @@ use miniquad::{conf, Context, EventHandlerFree, UserData};
 use crate::config::scion_config::{ScionConfig, ScionConfigReader};
 use crate::utils::time::Time;
 use crate::utils::window::WindowDimensions;
+use crate::renderer::RendererType;
 
 /// `Scion` is the entry point of any application made with Scion engine.
 pub struct Scion {
@@ -68,13 +69,15 @@ impl Scion {
 pub struct ScionBuilder {
     config: ScionConfig,
     schedule_builder: Builder,
+    renderer: RendererType
 }
 
 impl ScionBuilder {
     fn new(config: ScionConfig) -> Self {
         Self {
             config,
             schedule_builder: Default::default(),
+            renderer: Default::default()
         }
     }
 
@@ -88,14 +91,19 @@ impl ScionBuilder {
         self
     }
 
-    fn with_thread_local_fn<F: FnMut(&mut World, &mut Resources) + 'static>(
+    pub fn with_thread_local_fn<F: FnMut(&mut World, &mut Resources) + 'static>(
         mut self,
         function: F,
     ) -> Self {
         self.schedule_builder.add_thread_local_fn(function);
         self
     }
 
+    pub fn with_renderer(mut self, renderer_type: RendererType) -> Self{
+        self.renderer = renderer_type;
+        self
+    }
+
     /// Builds, setups and runs the Scion application
     pub fn run(mut self) {
         let scion = Scion {

src/config/scion_config.rs

@@ -23,7 +23,7 @@ impl Default for ScionConfig {
         Self {
             app_name: "Scion game".to_string(),
             logger_config: Some(Default::default()),
-            window_config: Some(Default::default())
+            window_config: Some(Default::default()),
         }
     }
 }

src/lib.rs

@@ -4,3 +4,4 @@ pub use legion;
 pub mod application;
 pub mod config;
 pub mod utils;
+pub mod renderer;

src/renderer/mod.rs

@@ -0,0 +1,20 @@
+use miniquad::Context;
+use legion::{World, Resources};
+
+/// Trait to implement in order to create a renderer to use in a `Scion` application
+pub trait ScionRenderer {
+    /// The draw method is called each frame
+    fn draw(&mut self, context: &mut Context, world: &mut World, resource: &mut Resources);
+}
+
+/// Type of renderer to use to render the game.
+pub enum RendererType {
+    Scion2D,
+    Custom(Box<dyn ScionRenderer>)
+}
+
+impl Default for RendererType{
+    fn default() -> Self {
+        RendererType::Scion2D
+    }
+}