Merge pull request #202 from gwilymk/animated-tiles

Add super simple animated tiles

agb/examples/animated_background.rs

@@ -0,0 +1,48 @@
+#![no_std]
+#![no_main]
+
+use agb::{
+    display::{
+        tiled::{TileFormat, TileSet, TileSetting},
+        Priority,
+    },
+    include_gfx,
+};
+
+include_gfx!("examples/water_tiles.toml");
+
+#[agb::entry]
+fn main(mut gba: agb::Gba) -> ! {
+    let (gfx, mut vram) = gba.display.video.tiled0();
+    let vblank = agb::interrupt::VBlank::get();
+
+    let tileset = TileSet::new(water_tiles::water_tiles.tiles, TileFormat::FourBpp);
+    let tileset_ref = vram.add_tileset(tileset);
+
+    vram.set_background_palettes(water_tiles::water_tiles.palettes);
+
+    let mut bg = gfx.background(Priority::P0);
+
+    for y in 0..20u16 {
+        for x in 0..30u16 {
+            bg.set_tile(
+                &mut vram,
+                (x, y).into(),
+                tileset_ref,
+                TileSetting::new(0, false, false, 0),
+            );
+        }
+    }
+
+    bg.commit();
+    bg.show();
+
+    let mut i = 0;
+    loop {
+        i = (i + 1) % 8;
+
+        vram.replace_tile(tileset_ref, 0, tileset_ref, i);
+
+        vblank.wait_for_vblank();
+    }
+}

agb/examples/water_tiles.toml

@@ -0,0 +1,5 @@
+version = "1.0"
+
+[image.water_tiles]
+filename = "water_tiles.png"
+tile_size = "8x8"

agb/src/display/tiled/vram_manager.rs

@@ -188,33 +188,10 @@ impl<'a> VRamManager<'a> {
 
         let new_reference: NonNull<u32> =
             unsafe { TILE_ALLOCATOR.alloc(TILE_LAYOUT) }.unwrap().cast();
-
-        let tile_slice = if let ArenaStorageItem::Data(data, generation) =
-            &self.tilesets[tile_set_ref.id as usize]
-        {
-            debug_assert_eq!(
-                *generation, tile_set_ref.generation,
-                "Stale tile data requested"
-            );
-
-            let tile_offset = (tile as usize) * data.format.tile_size();
-            &data.tiles[tile_offset..(tile_offset + data.format.tile_size())]
-        } else {
-            panic!("Tile set ref must point to existing tile set");
-        };
-
-        let tile_size_in_half_words = tile_slice.len() / 2;
-
-        unsafe {
-            dma_copy16(
-                tile_slice.as_ptr() as *const u16,
-                new_reference.as_ptr() as *mut u16,
-                tile_size_in_half_words,
-            );
-        }
-
         let tile_reference = TileReference(new_reference);
 
+        self.copy_tile_to_location(tile_set_ref, tile, tile_reference);
+
         let index = Self::index_from_reference(tile_reference);
 
         self.tile_set_to_vram
@@ -252,6 +229,54 @@ impl<'a> VRamManager<'a> {
         self.reference_counts[index].1 = None;
     }
 
+    pub fn replace_tile(
+        &mut self,
+        source_tile_set_ref: TileSetReference,
+        source_tile: u16,
+        target_tile_set_ref: TileSetReference,
+        target_tile: u16,
+    ) {
+        if let Some(&reference) = self
+            .tile_set_to_vram
+            .get(&(source_tile_set_ref.id, source_tile))
+        {
+            self.copy_tile_to_location(target_tile_set_ref, target_tile, reference);
+        }
+    }
+
+    fn copy_tile_to_location(
+        &self,
+        tile_set_ref: TileSetReference,
+        tile_id: u16,
+        tile_reference: TileReference,
+    ) {
+        let tile_slice = if let ArenaStorageItem::Data(data, generation) =
+            &self.tilesets[tile_set_ref.id as usize]
+        {
+            debug_assert_eq!(
+                *generation, tile_set_ref.generation,
+                "Stale tile data requested"
+            );
+
+            let tile_offset = (tile_id as usize) * data.format.tile_size();
+            &data.tiles[tile_offset..(tile_offset + data.format.tile_size())]
+        } else {
+            panic!("Target tile set ref must point to an existing tile set reference")
+        };
+
+        let tile_size_in_half_words = tile_slice.len() / 2;
+
+        let target_location = tile_reference.0.as_ptr() as *mut _;
+
+        unsafe {
+            dma_copy16(
+                tile_slice.as_ptr() as *const u16,
+                target_location,
+                tile_size_in_half_words,
+            )
+        };
+    }
+
     /// Copies raw palettes to the background palette without any checks.
     pub fn set_background_palette_raw(&mut self, palette: &[u16]) {
         unsafe {