Set falling sand chunk texure to random colours each frame

Cargo.lock

@@ -1893,6 +1893,7 @@ name = "haranae-rs"
 version = "0.1.0"
 dependencies = [
  "bevy",
+ "rand",
 ]
 
 [[package]]
@@ -2671,6 +2672,12 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
 [[package]]
 name = "proc-macro-crate"
 version = "1.3.1"
@@ -2711,6 +2718,36 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "17fd96390ed3feda12e1dfe2645ed587e0bea749e319333f104a33ff62f77a0b"
 
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
 [[package]]
 name = "range-alloc"
 version = "0.1.3"

Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 
 [dependencies]
 bevy = "0.12.1"
+rand = "0.8.5"
 
 [profile.dev.package."*"]
 opt-level = 3

src/falling_sand/mod.rs

@@ -11,12 +11,14 @@ use bevy::{
     sprite::SpriteBundle,
     transform::components::Transform,
 };
+use rand::random;
 
 pub struct FallingSandPlugin;
 
 impl Plugin for FallingSandPlugin {
     fn build(&self, app: &mut bevy::prelude::App) {
         app.add_systems(Startup, setup);
+        app.add_systems(Update, update_chunk_texture_system);
     }
 }
 
@@ -34,9 +36,44 @@ fn setup(mut commands: Commands, mut images: ResMut<Assets<Image>>) {
 
     let image_handle = images.add(image);
 
-    commands.spawn(SpriteBundle {
+    commands
+        .spawn(Chunk {
+            width: 256,
+            height: 256,
+        })
+        .insert(SpriteBundle {
             texture: image_handle,
             transform: Transform::from_translation(Vec3::new(256., 0., 0.)),
             ..default()
         });
 }
+
+#[derive(Component)]
+pub struct Chunk {
+    width: usize,
+    height: usize,
+}
+
+pub fn update_chunk_texture_system(
+    mut images: ResMut<Assets<Image>>,
+    mut chunk: Query<(&mut Chunk, &Handle<Image>)>,
+) {
+    // We know for now there's only one chunk
+    let chunk = chunk.get_single_mut();
+    if chunk.is_err() {
+        return;
+    }
+
+    let (chunk, image_handle) = chunk.unwrap();
+    let image = images.get_mut(image_handle).unwrap();
+    for y in 0..chunk.height {
+        for x in 0..chunk.width {
+            // Just set each pixel to random colours for now
+            let index = (x + y * chunk.width) * 4;
+            image.data[index] = random::<u8>();
+            image.data[index + 1] = random::<u8>();
+            image.data[index + 2] = random::<u8>();
+            image.data[index + 3] = 255;
+        }
+    }
+}