fix unloadng of temp terrain

src/tiles.rs

@@ -92,6 +92,10 @@ pub struct CurrentWorldSpriteState {
 }
 use std::time::Instant;
 
+#[derive(Component)]
+pub struct TerrainSprite;
+
+// TODO: re-rendering on z-index change is inefficient, replace with shifting pool system for z-index change
 pub fn build_world_sprites(
     mut query: Query<(&FloorTile, &Transform)>,
     mut commands: Commands,
@@ -99,10 +103,17 @@ pub fn build_world_sprites(
     textures: Res<Textures>,
     texture_ids: Res<TextureIDs>,
     z_index: ResMut<game::ZIndex>,
+    query_1: Query<Entity, With<TerrainSprite>>,
 ) {
     if cwss.state != WorldSpriteState::WaitingForRender {
         return;
     }
+
+    // despawn all query_1 entities
+    for entity in query_1.iter() {
+        commands.entity(entity).despawn();
+    }
+
     let now = Instant::now();
     if cwss.state == WorldSpriteState::WaitingForRender {
         cwss.state = WorldSpriteState::InProgress;
@@ -120,7 +131,7 @@ pub fn build_world_sprites(
                     image: texture.clone(),
                     ..Default::default()
                 };
-                commands.spawn((sprite, *transform));
+                commands.spawn((sprite, *transform, TerrainSprite));
             }
         }
         cwss.state = WorldSpriteState::RenderReady;