Add RandomTable for spawns.

src/core.rs

@@ -6,6 +6,7 @@ use std::{
 
 use bevy::{core::FloatOrd, prelude::*, transform::TransformSystem};
 use derive_more::{Deref, DerefMut};
+use rand::prelude::*;
 
 #[derive(Clone, Copy, Debug, Default, Deref, DerefMut, PartialEq, PartialOrd, Reflect)]
 #[reflect(Component)]
@@ -440,6 +441,45 @@ pub struct Pool<T> {
     pub max: T,
 }
 
+#[derive(Clone, Debug)]
+pub struct RandomTable<T>(Vec<T>)
+where
+    T: Clone;
+
+impl<T> RandomTable<T>
+where
+    T: Clone,
+{
+    pub fn add(&mut self, value: T, weight: u32) -> &mut Self {
+        for _ in 0..weight {
+            self.0.push(value.clone());
+        }
+        self
+    }
+}
+
+impl<T> Default for RandomTable<T>
+where
+    T: Clone,
+{
+    fn default() -> Self {
+        Self(vec![])
+    }
+}
+
+impl<T> Iterator for RandomTable<T>
+where
+    T: Clone,
+{
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let mut rng = thread_rng();
+        self.0.shuffle(&mut rng);
+        self.0.get(0).cloned()
+    }
+}
+
 fn copy_coordinates_to_transform(
     config: Res<CoreConfig>,
     mut query: Query<(&Coordinates, &mut Transform)>,