3 files changed, 134 insertions, 133 deletions

diff --git a/src/proc_gen/herringbone.rs b/src/proc_gen/herringbone.rs
index 271b7a1..e8569c8 100644
--- a/src/proc_gen/herringbone.rs
+++ b/src/proc_gen/herringbone.rs
@@ -1,111 +1,30 @@
 use fxhash::hash32;
 use glam::IVec2;
 
-use crate::{
-    config::TILESET_SCALING,
-    proc_gen::tileset_loader::{Tile, TileOrientation, Tileset, TilesetPixelType},
-};
+use crate::proc_gen::tileset_loader::TileOrientation;
 
-pub fn split_position(world: IVec2, tileset: &Tileset) -> (IVec2, IVec2, TileOrientation) {
-    let s = tileset.dimensions.short as i32;
-    let tx = world.x.div_euclid(s);
-    let ty = world.y.div_euclid(s);
-    let fx = world.x.rem_euclid(s);
-    let fy = world.y.rem_euclid(s);
-
-    match (tx - ty).rem_euclid(4) {
-        // left half of horizontal tile
-        0 => (
-            IVec2::new(tx, ty),
-            IVec2::new(fx, fy),
-            TileOrientation::Horizontal,
-        ),
-        // right half of horizontal tile
-        1 => (
-            IVec2::new(tx - 1, ty),
-            IVec2::new(fx + s, fy),
-            TileOrientation::Horizontal,
-        ),
-        // top half of vertical tile
-        3 => (
-            IVec2::new(tx, ty),
-            IVec2::new(fx, fy),
-            TileOrientation::Vertical,
-        ),
-        // bottom half of vertical tile
-        2 => (
-            IVec2::new(tx, ty - 1),
-            IVec2::new(fx, fy + s),
-            TileOrientation::Vertical,
-        ),
-        _ => unreachable!(),
+fn tile_starting_at(grid: IVec2) -> Option<TileOrientation> {
+    match (grid.x - grid.y).rem_euclid(4) {
+        // 1 is the right half of the horizontal tile starting at 0,
+        // 2 is the bottom half of the vertical tile starting at 3
+        0 => Some(TileOrientation::Horizontal),
+        3 => Some(TileOrientation::Vertical),
+        _ => None,
     }
 }
 
+pub fn tiles_overlapping(min: IVec2, max: IVec2) -> impl Iterator<Item = (IVec2, TileOrientation)> {
+    ((min.y - 1)..max.y)
+        .flat_map(move |y| ((min.x - 1)..max.x).map(move |x| IVec2::new(x, y)))
+        .filter_map(|grid| tile_starting_at(grid).map(|orientation| (grid, orientation)))
+}
+
 // better "%" for hashes since it prefers the high bits
 #[inline]
 fn reduce(h: u32, n: usize) -> usize {
     (((h as u128) * (n as u128)) >> 32) as usize
 }
 
-fn pick_variant(tile_pos: IVec2, orientation: TileOrientation, tileset: &Tileset) -> &Tile {
-    let h = hash32(&tile_pos);
-    match orientation {
-        TileOrientation::Horizontal => {
-            &tileset.horizontal_tiles[reduce(h, tileset.horizontal_tiles.len())]
-        }
-        TileOrientation::Vertical => {
-            &tileset.vertical_tiles[reduce(h, tileset.vertical_tiles.len())]
-        }
-    }
-}
-
-// TODO: optimize
-fn get_pixel_at_position(world: IVec2, tileset: &Tileset) -> TilesetPixelType {
-    let scaled_world = world.div_euclid(IVec2::new(TILESET_SCALING, TILESET_SCALING));
-    let (tile_pos, local, orientation) = split_position(scaled_world, tileset);
-    let tile = pick_variant(tile_pos, orientation, tileset);
-    let width = match orientation {
-        TileOrientation::Horizontal => tileset.dimensions.long as i32,
-        TileOrientation::Vertical => tileset.dimensions.short as i32,
-    };
-    tile.pixels[(local.x + local.y * width) as usize]
+pub fn variant_index(grid: IVec2, variants: usize) -> usize {
+    reduce(hash32(&grid), variants)
 }
-
-pub fn tiles_overlapping(
-    a: IVec2,
-    b: IVec2,
-    tileset: &Tileset,
-) -> impl Iterator<Item = (IVec2, &Tile, TileOrientation)> {
-    let s = IVec2::new(
-        tileset.dimensions.short as i32,
-        tileset.dimensions.short as i32,
-    );
-
-    let ta = a.div_euclid(s) - 1;
-    let tb = (b - 1).div_euclid(s);
-
-    (ta.y..=tb.y)
-        .flat_map(move |ty| (ta.x..=tb.x).map(move |tx| (tx, ty)))
-        .filter_map(move |(tx, ty)| match (tx - ty).rem_euclid(4) {
-            0 => Some((
-                IVec2::new(tx, ty),
-                pick_variant(IVec2::new(tx, ty), TileOrientation::Horizontal, tileset),
-                TileOrientation::Horizontal,
-            )),
-            3 => Some((
-                IVec2::new(tx, ty),
-                pick_variant(IVec2::new(tx, ty), TileOrientation::Vertical, tileset),
-                TileOrientation::Vertical,
-            )),
-            _ => None,
-        })
-}
-
-// pub fn get_cell_at_position(world: IVec2, tileset: &Tileset) -> Cell {
-//     let pixel = get_pixel_at_position(world, tileset);
-//     match pixel {
-//         TilesetPixelType::Void => Cell::void(),
-//         TilesetPixelType::Terrain => Cell::from_material(MaterialId::Dirt),
-//     }
-// }
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 (grid_position, orientation) in tiles {
+            let tile = self.tile_at(grid_position, orientation);
+            let tile_min = grid_position * grid;
 
-        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 {
+            // 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
     }
 }
diff --git a/src/proc_gen/tileset_loader.rs b/src/proc_gen/tileset_loader.rs
index acb4d65..e0d9d18 100644
--- a/src/proc_gen/tileset_loader.rs
+++ b/src/proc_gen/tileset_loader.rs
@@ -1,6 +1,9 @@
+use glam::IVec2;
 use serde::Deserialize;
 use std::{collections::HashMap, error::Error, fs::File, io::BufReader, path::Path};
 
+use crate::sim::lib::marching_squares::Marchable;
+
 fn load_img(path: &Path) -> Result<(Vec<u8>, u32, u32), Box<dyn Error>> {
     let mut decoder = png::Decoder::new(BufReader::new(File::open(path)?));
     decoder.set_transformations(png::Transformations::IDENTITY);
@@ -32,7 +35,7 @@ pub struct TileDimensions {
     pub long: u32,
 }
 
-#[derive(Deserialize, Clone, Copy, Debug)]
+#[derive(Deserialize, Clone, Copy, Debug, PartialEq, Eq)]
 pub enum TilesetPixelType {
     Void = 0,
     Terrain,
@@ -55,6 +58,54 @@ pub struct Tile {
     pub pixels: Vec<TilesetPixelType>,
 }
 
+// TODO might want to use newtypes to hoist to biome
+impl Marchable for Tile {
+    fn occupied(&self, pos: IVec2) -> bool {
+        // TODO this will break for tileset dimensions other than 22x44
+        if pos.x < 0 || pos.x >= self.size().x || pos.y < 0 || pos.y >= self.size().y {
+            match self.orientation {
+                TileOrientation::Horizontal => {
+                    let a = (pos.x == -1 || pos.x == (self.dimensions.long as i32))
+                        && pos.y >= 8
+                        && pos.y <= 13;
+                    let b = (pos.y == -1 || pos.y == (self.dimensions.short as i32))
+                        && ((pos.x >= 8 && pos.x <= 13) || (pos.x >= 30 && pos.x <= 35));
+                    !(a || b)
+                }
+                TileOrientation::Vertical => {
+                    let a = (pos.y == -1 || pos.y == (self.dimensions.long as i32))
+                        && pos.x >= 8
+                        && pos.x <= 13;
+                    let b = (pos.x == -1 || pos.x == (self.dimensions.short as i32))
+                        && ((pos.y >= 8 && pos.y <= 13) || (pos.y >= 30 && pos.y <= 35));
+                    !(a || b)
+                }
+            }
+        } else {
+            self.pixel_at(pos) == TilesetPixelType::Terrain
+        }
+    }
+    fn marchable_size(&self) -> IVec2 {
+        self.size()
+    }
+}
+
+impl Tile {
+    pub fn size(&self) -> IVec2 {
+        let short = self.dimensions.short as i32;
+        let long = self.dimensions.long as i32;
+        match self.orientation {
+            TileOrientation::Horizontal => IVec2::new(long, short),
+            TileOrientation::Vertical => IVec2::new(short, long),
+        }
+    }
+
+    #[inline]
+    pub fn pixel_at(&self, position: IVec2) -> TilesetPixelType {
+        self.pixels[(position.x + position.y * self.size().x) as usize]
+    }
+}
+
 #[derive(Debug)]
 pub struct Tileset {
     pub dimensions: TileDimensions,