From baad8b54bdff624b648af7bcf977f14711ff59bc Mon Sep 17 00:00:00 2001
From: Tom Barrett <tom@tombarrett.xyz>
Date: Sat, 20 Mar 2021 14:00:10 +0100
Subject: populate top row with new gems

---
 src/main.rs | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index acecaad..f3d41b0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,12 +1,44 @@
 use bevy::math::Vec3;
 use bevy::prelude::*;
-use gems::constants;
+use rand::{
+    distributions::{Distribution, Standard},
+    Rng,
+};
 
+#[derive(Debug, PartialEq)]
 enum Occupant {
     None,
     Green,
+    Yellow,
+    Red,
+    Diamond,
 }
 
+impl Occupant {
+    pub fn to_index(&self) -> u32 {
+        match self {
+            Occupant::Green => 0,
+            Occupant::Yellow => 1,
+            Occupant::Red => 2,
+            Occupant::Diamond => 3,
+            Occupant::None => 13,
+        }
+    }
+}
+
+impl Distribution<Occupant> for Standard {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Occupant {
+        match rng.gen_range(0..=3) {
+            0 => Occupant::Green,
+            1 => Occupant::Yellow,
+            2 => Occupant::Diamond,
+            3 => Occupant::Red,
+            _ => Occupant::None,
+        }
+    }
+}
+
+#[derive(Debug)]
 struct Cell {
     x: u8,
     y: u8,
@@ -23,6 +55,17 @@ impl Cell {
     }
 }
 
+fn cell_falling_system(mut cell_query: Query<(&mut Cell, &mut TextureAtlasSprite)>) {
+    for (mut cell, mut sprite) in cell_query.iter_mut() {
+        if cell.occupant == Occupant::None {
+            if cell.y == 7 {
+                cell.occupant = rand::random();
+                sprite.index = cell.occupant.to_index();
+            }
+        }
+    }
+}
+
 pub fn setup(
     commands: &mut Commands,
     asset_server: Res<AssetServer>,
@@ -81,20 +124,22 @@ pub fn setup(
 
     for i in 0..8 {
         for j in 0..8 {
-            commands.spawn(SpriteSheetBundle {
-                sprite: TextureAtlasSprite::new(1),
-                texture_atlas: atlas_handle.clone(),
-                transform: Transform {
-                    translation: Vec3 {
-                        x: ((i as f32) * 16.0 * 3.5) - 320.0,
-                        y: ((j as f32) * 16.0 * 3.5) - 170.0,
-                        z: 0.0,
+            commands
+                .spawn(SpriteSheetBundle {
+                    texture_atlas: atlas_handle.clone(),
+                    sprite: TextureAtlasSprite::new(11),
+                    transform: Transform {
+                        translation: Vec3 {
+                            x: ((i as f32) * 16.0 * 3.5) - 320.0,
+                            y: ((j as f32) * 16.0 * 3.5) - 160.0,
+                            z: 0.0,
+                        },
+                        scale: Vec3::splat(3.5),
+                        ..Default::default()
                     },
-                    scale: Vec3::splat(3.5),
                     ..Default::default()
-                },
-                ..Default::default()
-            });
+                })
+                .with(Cell::new(i, j));
         }
     }
 }
@@ -103,6 +148,7 @@ pub struct GemsPlugin;
 impl Plugin for GemsPlugin {
     fn build(&self, app: &mut AppBuilder) {
         app.add_startup_system(setup.system());
+        app.add_system(cell_falling_system.system());
     }
 }
 
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