From d68cf09f7b8e5cb783dc495097c17eaf2a4d5427 Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Mon, 31 Aug 2026 00:03:32 -0700
Subject: cleanup

---
 src/proc_gen/mod.rs | 101 ++++++++++++++++++++++++++++++++++------------------
 1 file changed, 66 insertions(+), 35 deletions(-)

(limited to 'src/proc_gen/mod.rs')

diff --git a/src/proc_gen/mod.rs b/src/proc_gen/mod.rs
index 049ad1a..caec241 100644
--- a/src/proc_gen/mod.rs
+++ b/src/proc_gen/mod.rs
@@ -6,66 +6,97 @@ use glam::IVec2;
 use crate::{
     config::{CHUNK_SIZE, TILESET_SCALING},
     proc_gen::{
-        herringbone::tiles_overlapping,
+        herringbone::{tiles_overlapping, variant_index},
         tileset_loader::{Tile, TileOrientation, Tileset, load_tileset},
     },
     sim::{cell::Cell, cell_manager::chunk::Chunk, entity::EntityDef},
 };
 
+pub struct TileCells {
+    pub size: IVec2,
+    pub cells: Vec<Cell>,
+}
+
 pub trait Biome {
-    fn derive_world_from_tile(&self, _tile: &Tile) -> Vec<Cell> {
-        Vec::new()
-    }
-    fn derive_entities_from_tile(&self, _tile: &Tile) -> Vec<EntityDef> {
+    fn derive_world_from_tile(&self, tile: &Tile) -> TileCells;
+    fn derive_entities_from_tile(&self, tile: &Tile) -> Vec<EntityDef> {
         Vec::new()
     }
 }
 
 pub struct TilesetWorldGenerator {
     tileset: Tileset,
-    biome: Box<dyn Biome>,
+    horizontal_tiles: Vec<TileCells>,
+    vertical_tiles: Vec<TileCells>,
 }
 
 impl TilesetWorldGenerator {
+    pub fn new(tileset_path: &str, biome: &dyn Biome) -> Self {
+        let tileset = load_tileset(tileset_path);
+
+        let horizontal_tiles = tileset
+            .horizontal_tiles
+            .iter()
+            .map(|tile| biome.derive_world_from_tile(tile))
+            .collect();
+        let vertical_tiles = tileset
+            .vertical_tiles
+            .iter()
+            .map(|tile| biome.derive_world_from_tile(tile))
+            .collect();
+
+        TilesetWorldGenerator {
+            tileset,
+            horizontal_tiles,
+            vertical_tiles,
+        }
+    }
+
+    fn grid_size(&self) -> IVec2 {
+        IVec2::splat(self.tileset.dimensions.short as i32 * TILESET_SCALING)
+    }
+
+    fn tile_at(&self, grid: IVec2, orientation: TileOrientation) -> &TileCells {
+        let tiles = match orientation {
+            TileOrientation::Horizontal => &self.horizontal_tiles,
+            TileOrientation::Vertical => &self.vertical_tiles,
+        };
+        &tiles[variant_index(grid, tiles.len())]
+    }
+
     pub fn generate_chunk(&self, chunk_position: IVec2) -> Chunk {
         let mut chunk = Chunk::void();
 
-        let a = chunk_position * CHUNK_SIZE;
-        let b = (chunk_position + 1) * CHUNK_SIZE;
-        let tiles = tiles_overlapping(a * TILESET_SCALING, b * TILESET_SCALING, &self.tileset);
-        let world_tiles = tiles.map(|(p, t, o)| (p, self.biome.derive_world_from_tile(t), o));
+        let chunk_min = chunk_position * CHUNK_SIZE;
+        let chunk_max = chunk_min + CHUNK_SIZE;
+
+        let grid = self.grid_size();
+        let tiles = tiles_overlapping(
+            chunk_min.div_euclid(grid),
+            (chunk_max - 1).div_euclid(grid) + 1,
+        );
 
-        for (tp, t, o) in world_tiles {
-            let p = tp * self.tileset.dimensions.short as i32 * TILESET_SCALING;
-            let ta = p.max(a);
-            let tb = p.min(b);
-            if ta.x >= tb.x || ta.y >= tb.y {
+        for (grid_position, orientation) in tiles {
+            let tile = self.tile_at(grid_position, orientation);
+            let tile_min = grid_position * grid;
+
+            // subset of tile in chunk
+            let min = tile_min.max(chunk_min);
+            let max = (tile_min + tile.size).min(chunk_max);
+            if min.x >= max.x {
                 continue;
             }
+            let width = (max.x - min.x) as usize;
 
-            for y in ta.y..tb.y {
-                for x in ta.x..tb.x {
-                    let sw = match o {
-                        TileOrientation::Horizontal => {
-                            self.tileset.dimensions.long as i32 * TILESET_SCALING
-                        }
-                        TileOrientation::Vertical => {
-                            self.tileset.dimensions.short as i32 * TILESET_SCALING
-                        }
-                    };
-
-                    let src = (y - p.y) * sw + (x - p.x);
-                    let dst = (y - a.y) * CHUNK_SIZE + (x - a.x);
-                    chunk.cells[dst as usize] = t[src as usize];
-                }
+            for y in min.y..max.y {
+                let src = ((y - tile_min.y) * tile.size.x + (min.x - tile_min.x)) as usize;
+                let dst = ((y - chunk_min.y) * CHUNK_SIZE + (min.x - chunk_min.x)) as usize;
+                chunk.cells[dst..dst + width].copy_from_slice(&tile.cells[src..src + width]);
             }
         }
 
-        chunk
-    }
+        chunk.mark_collider_dirty(0);
 
-    pub fn new(tileset_path: &str, biome: Box<dyn Biome>) -> Self {
-        let tileset = load_tileset(tileset_path);
-        TilesetWorldGenerator { tileset, biome }
+        chunk
     }
 }
-- 
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