Slapping a grid on it

Author: marcusbuffett

src/main.rs

@@ -2,6 +2,29 @@ use bevy::prelude::*;
 
 const SNAKE_HEAD_COLOR: Color = Color::rgb(0.7, 0.7, 0.7);
 
+const ARENA_HEIGHT: u32 = 10;
+const ARENA_WIDTH: u32 = 10;
+
+#[derive(Component, Clone, Copy, PartialEq, Eq)]
+struct Position {
+    x: i32,
+    y: i32,
+}
+
+#[derive(Component)]
+struct Size {
+    width: f32,
+    height: f32,
+}
+impl Size {
+    pub fn square(x: f32) -> Self {
+        Self {
+            width: x,
+            height: x,
+        }
+    }
+}
+
 #[derive(Component)]
 struct SnakeHead;
 
@@ -22,7 +45,9 @@ fn spawn_snake(mut commands: Commands) {
             },
             ..default()
         })
-        .insert(SnakeHead);
+        .insert(SnakeHead)
+        .insert(Position { x: 3, y: 3 })
+        .insert(Size::square(0.8));
 }
 
 fn snake_movement(
@@ -45,11 +70,43 @@ fn snake_movement(
     }
 }
 
+fn size_scaling(windows: Res<Windows>, mut q: Query<(&Size, &mut Transform)>) {
+    let window = windows.get_primary().unwrap();
+    for (sprite_size, mut transform) in q.iter_mut() {
+        transform.scale = Vec3::new(
+            sprite_size.width / ARENA_WIDTH as f32 * window.width() as f32,
+            sprite_size.height / ARENA_HEIGHT as f32 * window.height() as f32,
+            1.0,
+        );
+    }
+}
+
+fn position_translation(windows: Res<Windows>, mut q: Query<(&Position, &mut Transform)>) {
+    fn convert(pos: f32, bound_window: f32, bound_game: f32) -> f32 {
+        let tile_size = bound_window / bound_game;
+        pos / bound_game * bound_window - (bound_window / 2.) + (tile_size / 2.)
+    }
+    let window = windows.get_primary().unwrap();
+    for (pos, mut transform) in q.iter_mut() {
+        transform.translation = Vec3::new(
+            convert(pos.x as f32, window.width() as f32, ARENA_WIDTH as f32),
+            convert(pos.y as f32, window.height() as f32, ARENA_HEIGHT as f32),
+            0.0,
+        );
+    }
+}
+
 fn main() {
     App::new()
         .add_startup_system(setup_camera)
         .add_startup_system(spawn_snake)
         .add_system(snake_movement)
+        .add_system_set_to_stage(
+            CoreStage::PostUpdate,
+            SystemSet::new()
+                .with_system(position_translation)
+                .with_system(size_scaling),
+        )
         .add_plugins(DefaultPlugins)
         .run();
 }