Deduplicate background tiles (#477)

This started as an attempt to get dungeon puzzler in the combo rom,
ended up fixing a _load_ of 256 colour bugs and the ability to
deduplicate tiles you import.

Fixes #448

- [x] Changelog updated / no changelog update needed

CHANGELOG.md

@@ -12,14 +12,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - New tracker for playing XM files (see the `agb-tracker` crate).
 - You can now declare where looping sound channels should restart.
 - Fixnums now have constructors from_f32 and from_f64. This is mainly useful if using agb-fixnum outside of the Game Boy Advance e.g. in build scripts or macros.
+- New option when loading a background to automatically deduplicate tiles.
+- Methods on tile_setting to toggle its hflip and vflip status.
 
 ### Changed
 
 - Sound channel panning and volume options are now `Num<i16, 8>` rather than `Num<i16, 4>` for improved precision and sound quality.
 - Due to dependency changes, agb-gbafix is now released under MPL rather than GPL.
+- `include_background_gfx!` now produces tile settings directly rather than palette assigments.
 
 ### Fixed
 
+- 256-colour backgrounds are better supported.
 - Mono looping samples will now correctly play to the end if it doesn't perfectly align with a buffer boundry and short samples now also loop correctly.
 
 ## [0.16.0] - 2023/07/18

agb-image-converter/src/config.rs

@@ -11,4 +11,5 @@ pub(crate) trait Config {
 pub(crate) trait Image {
     fn filename(&self) -> String;
     fn colours(&self) -> Colours;
+    fn deduplicate(&self) -> bool;
 }

agb-image-converter/src/deduplicator.rs

@@ -0,0 +1,152 @@
+use std::{collections::HashMap, hash::BuildHasher};
+
+use crate::{colour::Colour, image_loader::Image};
+
+pub struct Transformation {
+    pub vflip: bool,
+    pub hflip: bool,
+}
+
+impl Transformation {
+    pub fn none() -> Self {
+        Self {
+            vflip: false,
+            hflip: false,
+        }
+    }
+
+    pub fn vflipped() -> Self {
+        Self {
+            vflip: true,
+            hflip: false,
+        }
+    }
+
+    pub fn hflipped() -> Self {
+        Self {
+            vflip: false,
+            hflip: true,
+        }
+    }
+
+    pub fn vhflipped() -> Self {
+        Self {
+            vflip: true,
+            hflip: true,
+        }
+    }
+}
+
+pub struct DeduplicatedData {
+    pub new_index: usize,
+    pub transformation: Transformation,
+}
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+struct Tile {
+    data: [Colour; 64],
+}
+
+impl Tile {
+    fn split_image(input: &Image) -> Vec<Self> {
+        let mut ret = vec![];
+
+        for y in 0..(input.height / 8) {
+            for x in 0..(input.width / 8) {
+                let mut tile_data = Vec::with_capacity(64);
+
+                for j in 0..8 {
+                    for i in 0..8 {
+                        tile_data.push(input.colour(x * 8 + i, y * 8 + j));
+                    }
+                }
+
+                ret.push(Tile {
+                    data: tile_data.try_into().unwrap(),
+                });
+            }
+        }
+
+        ret
+    }
+
+    fn vflipped(&self) -> Self {
+        let mut new_data = self.data;
+        for y in 0..4 {
+            for x in 0..8 {
+                new_data.swap(y * 8 + x, (7 - y) * 8 + x);
+            }
+        }
+
+        Self { data: new_data }
+    }
+
+    fn hflipped(&self) -> Self {
+        let mut new_data = self.data;
+
+        for y in 0..8 {
+            for x in 0..4 {
+                new_data.swap(y * 8 + x, y * 8 + (7 - x));
+            }
+        }
+
+        Self { data: new_data }
+    }
+}
+
+pub(crate) fn deduplicate_image(input: &Image, can_flip: bool) -> (Image, Vec<DeduplicatedData>) {
+    let mut resulting_tiles = vec![];
+    let mut deduplication_data = vec![];
+
+    let all_tiles = Tile::split_image(input);
+    let mut existing_tiles = HashMap::new();
+
+    let hasher = std::collections::hash_map::RandomState::new();
+
+    for tile in all_tiles {
+        let (tile, transformation) = if can_flip {
+            let vflipped = tile.vflipped();
+            let hflipped = tile.hflipped();
+            let vhflipped = vflipped.hflipped();
+
+            // find the one with the smallest hash
+            let tile_hash = hasher.hash_one(&tile);
+            let vflipped_hash = hasher.hash_one(&vflipped);
+            let hflipped_hash = hasher.hash_one(&hflipped);
+            let vhflipped_hash = hasher.hash_one(&vhflipped);
+
+            let minimum = tile_hash
+                .min(vflipped_hash)
+                .min(hflipped_hash)
+                .min(vhflipped_hash);
+
+            if minimum == tile_hash {
+                (tile, Transformation::none())
+            } else if minimum == vflipped_hash {
+                (vflipped, Transformation::vflipped())
+            } else if minimum == hflipped_hash {
+                (hflipped, Transformation::hflipped())
+            } else {
+                (vhflipped, Transformation::vhflipped())
+            }
+        } else {
+            (tile, Transformation::none())
+        };
+
+        let index = *existing_tiles.entry(tile.clone()).or_insert_with(|| {
+            resulting_tiles.push(tile);
+            resulting_tiles.len() - 1
+        });
+
+        deduplication_data.push(DeduplicatedData {
+            new_index: index,
+            transformation,
+        });
+    }
+
+    let image_data = resulting_tiles
+        .iter()
+        .flat_map(|tile| tile.data)
+        .collect::<Vec<_>>();
+    (Image::from_colour_data(image_data), deduplication_data)
+}

agb-image-converter/src/image_loader.rs

@@ -4,6 +4,7 @@ use image::{DynamicImage, GenericImageView};
 
 use crate::colour::Colour;
 
+#[derive(Clone)]
 pub(crate) struct Image {
     pub width: usize,
     pub height: usize,
@@ -42,6 +43,14 @@ impl Image {
         }
     }
 
+    pub fn from_colour_data(colour_data: Vec<Colour>) -> Self {
+        Self {
+            height: colour_data.len() / 8,
+            colour_data,
+            width: 8,
+        }
+    }
+
     pub fn colour(&self, x: usize, y: usize) -> Colour {
         self.colour_data[x + y * self.width]
     }

agb-image-converter/src/lib.rs

@@ -15,6 +15,7 @@ use quote::{format_ident, quote, ToTokens};
 mod aseprite;
 mod colour;
 mod config;
+mod deduplicator;
 mod font_loader;
 mod image_loader;
 mod palette16;
@@ -36,6 +37,7 @@ struct BackgroundGfxOption {
     module_name: String,
     file_name: String,
     colours: Colours,
+    deduplicate: bool,
 }
 
 impl config::Image for BackgroundGfxOption {
@@ -46,6 +48,10 @@ impl config::Image for BackgroundGfxOption {
     fn colours(&self) -> Colours {
         self.colours
     }
+
+    fn deduplicate(&self) -> bool {
+        self.deduplicate
+    }
 }
 
 impl Parse for BackgroundGfxOption {
@@ -72,12 +78,30 @@ impl Parse for BackgroundGfxOption {
             Colours::Colours16
         };
 
+        let lookahead = input.lookahead1();
+
+        let deduplicate = if lookahead.peek(syn::Ident) {
+            let deduplicate: syn::Ident = input.parse()?;
+
+            if deduplicate == "deduplicate" {
+                true
+            } else {
+                return Err(syn::Error::new_spanned(
+                    deduplicate,
+                    "Must either be the literal deduplicate or missing",
+                ));
+            }
+        } else {
+            false
+        };
+
         let file_name: syn::LitStr = input.parse()?;
 
         Ok(Self {
             module_name: module_name.to_string(),
             file_name: file_name.value(),
             colours,
+            deduplicate,
         })
     }
 }
@@ -406,6 +430,7 @@ fn convert_image(
 ) -> proc_macro2::TokenStream {
     let image_filename = &parent.join(settings.filename());
     let image = Image::load_from_file(image_filename);
+    let deduplicate = settings.deduplicate();
 
     rust_generator::generate_code(
         variable_name,
@@ -414,6 +439,7 @@ fn convert_image(
         &image_filename.to_string_lossy(),
         crate_prefix.to_owned(),
         assignment_offset,
+        deduplicate,
     )
 }
 
@@ -468,7 +494,14 @@ fn palette_tile_data(
     let mut tile_data = Vec::new();
 
     for (image_idx, image) in images.iter().enumerate() {
-        add_image_to_tile_data(&mut tile_data, image, optimiser, image_idx, true)
+        add_image_to_tile_data(
+            &mut tile_data,
+            image,
+            optimiser,
+            image_idx,
+            true,
+            &(0..images.len()).collect::<Vec<_>>(),
+        );
     }
 
     let tile_data = collapse_to_4bpp(&tile_data);
@@ -491,6 +524,7 @@ fn add_image_to_tile_data(
     optimiser: &Palette16OptimisationResults,
     assignment_offset: usize,
     is_sprite: bool,
+    remap_index: &[usize],
 ) {
     let tile_size = 8;
     let tiles_x = image.width / tile_size;
@@ -501,7 +535,7 @@ fn add_image_to_tile_data(
             let assignment = if is_sprite {
                 assignment_offset
             } else {
-                y * tiles_x + x + assignment_offset
+                remap_index[y * tiles_x + x] + assignment_offset
             };
 
             let palette_index = optimiser.assignments[assignment];