fix terrain z scrolling

src/tiles.rs

@@ -1,5 +1,5 @@
 use crate::tile::{FixtureTile, FloorTile, NeedsOccluded, TileState};
-use crate::{constants::*, game};
+use crate::{constants::*, game, tilemap};
 use bevy::prelude::*;
 use bevy_platform::collections::hash_map::HashMap;
 
@@ -92,34 +92,34 @@ pub struct CurrentWorldSpriteState {
 use std::time::Instant;
 
 #[derive(Component)]
-pub struct TerrainSprite;
+pub struct TerrainSprite {
+    pub z_index: usize, // Store the z-index this sprite belongs to (as world_Z)
+}
 
-// TODO: re-rendering on z-index change is inefficient, replace with shifting pool system for z-index change
+// This system generates sprites for all z-indices and stores references to them
 pub fn build_world_sprites(
-    mut query: Query<(&FloorTile, &Transform)>,
+    query: Query<(&FloorTile, &Transform)>,
     mut commands: Commands,
     mut cwss: ResMut<CurrentWorldSpriteState>,
     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
+    let now = Instant::now();
+    cwss.state = WorldSpriteState::InProgress;
+
+    // despawn all existing terrain sprites
     for entity in query_1.iter() {
         commands.entity(entity).despawn();
     }
 
-    let now = Instant::now();
-    if cwss.state == WorldSpriteState::WaitingForRender {
-        cwss.state = WorldSpriteState::InProgress;
-        let z_index = (z_index.0 as i32 + 150) as usize;
-        println!("z_index = {}", z_index);
-
-        for (floortile, transform) in query.iter_mut() {
+    // Generate sprites for all z-indices (0 to 150)
+    for z_index in 0..=tilemap::Z_TOTAL as usize {
+        for (floortile, transform) in query.iter() {
             let is_visible =
                 (floortile.visible_range[z_index / 32] & (1 << (z_index % 32) as u32)) != 0;
             if is_visible {
@@ -130,14 +130,23 @@ pub fn build_world_sprites(
                     image: texture.clone(),
                     ..Default::default()
                 };
-                commands.spawn((sprite, *transform, TerrainSprite));
+
+                // Spawn with hidden visibility initially - update_tile_visibility will handle showing/hiding
+                commands.spawn((
+                    sprite,
+                    *transform,
+                    TerrainSprite { z_index },
+                    Visibility::Hidden,
+                ));
             }
         }
-        cwss.state = WorldSpriteState::RenderReady;
     }
-    println!("{:?}", cwss.state);
+
+    cwss.state = WorldSpriteState::RenderReady;
+
     let elapsed = now.elapsed();
-    println!("Elapsed: {:.2?}", elapsed);
+
+    println!("World sprites built. Elapsed: {:.2?}", elapsed);
 }
 
 #[derive(Bundle)]