sprite: dynamically resize atlas during build

crates/bevy_render/src/texture/texture.rs

@@ -12,20 +12,39 @@ use std::collections::HashSet;
 pub const TEXTURE_ASSET_INDEX: usize = 0;
 pub const SAMPLER_ASSET_INDEX: usize = 1;
 
+#[derive(Default)]
 pub struct Texture {
     pub data: Vec<u8>,
     pub size: Vec2,
 }
 
+const FORMAT_SIZE: usize = 4; // TODO: get this from an actual format type
+
 impl Texture {
     pub fn new(data: Vec<u8>, size: Vec2) -> Self {
         Self { data, size }
     }
 
+    pub fn new_fill(size: Vec2, pixel: &[u8]) -> Self {
+        let mut value = Self::default();
+        value.resize(size);
+        for current_pixel in value.data.chunks_exact_mut(pixel.len()) {
+            current_pixel.copy_from_slice(&pixel);
+        }
+        value
+    }
+
     pub fn aspect(&self) -> f32 {
         self.size.y() / self.size.x()
     }
 
+    pub fn resize(&mut self, size: Vec2) {
+        self.size = size;
+        let width = size.x() as usize;
+        let height = size.y() as usize;
+        self.data.resize(width * height * FORMAT_SIZE, 0);
+    }
+
     pub fn texture_resource_system(
         mut state: ResMut<TextureResourceSystemState>,
         render_resources: Res<RenderResources>,

crates/bevy_sprite/src/texture_atlas_builder.rs

@@ -1,42 +1,89 @@
-use crate::{TextureAtlas, Rect};
+use crate::{Rect, TextureAtlas};
 use bevy_asset::{Assets, Handle};
 use bevy_render::texture::Texture;
 use glam::Vec2;
-use guillotiere::{size2, Allocation, AtlasAllocator};
+use guillotiere::{size2, AllocId, Allocation, AtlasAllocator};
 use std::collections::HashMap;
 
 pub struct TextureAtlasBuilder {
-    pub texture_allocations: Vec<(Handle<Texture>, Allocation)>,
+    pub texture_allocations: HashMap<Handle<Texture>, Allocation>,
+    pub allocation_textures: HashMap<AllocId, Handle<Texture>>,
     pub atlas_allocator: AtlasAllocator,
-    pub texture: Texture,
+    pub atlas_texture: Texture,
+    pub max_size: Vec2,
 }
 
 impl Default for TextureAtlasBuilder {
     fn default() -> Self {
-        Self::new(Vec2::new(256., 256.))
+        Self::new(Vec2::new(256., 256.), Vec2::new(2048., 2048.))
     }
 }
 
 const FORMAT_SIZE: usize = 4; // TODO: get this from an actual format type
 impl TextureAtlasBuilder {
-    pub fn new(initial_size: Vec2) -> Self {
-        let width = initial_size.x() as usize;
-        let height = initial_size.y() as usize;
+    pub fn new(initial_size: Vec2, max_size: Vec2) -> Self {
         Self {
             texture_allocations: Default::default(),
-            atlas_allocator: AtlasAllocator::new(size2(width as i32, height as i32)),
-            texture: Texture::new(vec![0; width * height * FORMAT_SIZE], initial_size),
+            allocation_textures: Default::default(),
+            atlas_allocator: AtlasAllocator::new(to_size2(initial_size)),
+            atlas_texture: Texture::new_fill(initial_size, &[0,0,0,0]),
+            max_size,
         }
     }
 
-    pub fn add_texture(&mut self, texture_handle: Handle<Texture>, texture: &Texture) {
-        // TODO: resize if allocation fails
-        let allocation = self
-            .atlas_allocator
-            .allocate(size2(texture.size.x() as i32, texture.size.y() as i32))
-            .unwrap();
+    pub fn add_texture(&mut self, texture_handle: Handle<Texture>, textures: &Assets<Texture>) {
+        let texture = textures.get(&texture_handle).unwrap();
+        let mut queued_textures= vec![texture_handle];
+        loop {
+            let mut failed_textures = Vec::new();
+            while let Some(texture_handle) = queued_textures.pop() {
+                let allocation = self
+                    .atlas_allocator
+                    .allocate(size2(texture.size.x() as i32, texture.size.y() as i32));
+                if let Some(allocation) = allocation {
+                    self.place_texture(allocation, texture_handle, texture);
+                } else {
+                    failed_textures.push(texture_handle);
+                }
+            }
+
+            if failed_textures.len() == 0 {
+                break;
+            }
+
+            queued_textures = failed_textures;
+
+            // if allocation failed, resize the atlas
+            let new_size = self.atlas_texture.size * 2.0;
+            if new_size > self.max_size {
+                panic!(
+                    "Ran out of space in Atlas. This atlas cannot be larger than: {:?}",
+                    self.max_size
+                );
+            }
+
+            let new_size2 = to_size2(new_size);
+            self.atlas_texture = Texture::new_fill(new_size, &[0,0,0,0]);
+            let change_list = self.atlas_allocator.resize_and_rearrange(new_size2);
+
+            for change in change_list.changes {
+                if let Some(changed_texture_handle) = self.allocation_textures.remove(&change.old.id) {
+                    self.texture_allocations.remove(&changed_texture_handle);
+                    let changed_texture = textures.get(&changed_texture_handle).unwrap();
+                    self.place_texture(change.new, changed_texture_handle, changed_texture);
+                }
+            }
+
+            for failure in change_list.failures {
+                let failed_texture = self.allocation_textures.remove(&failure.id).unwrap();
+                queued_textures.push(failed_texture);
+            }
+        }
+    }
+
+    fn place_texture(&mut self, allocation: Allocation, texture_handle: Handle<Texture>, texture: &Texture) {
         let rect = allocation.rectangle;
-        let atlas_width = self.texture.size.x() as usize;
+        let atlas_width = self.atlas_texture.size.x() as usize;
         let rect_width = rect.width() as usize;
 
         for (texture_y, bound_y) in (rect.min.y..rect.max.y).map(|i| i as usize).enumerate() {
@@ -44,15 +91,17 @@ impl TextureAtlasBuilder {
             let end = begin + rect_width * FORMAT_SIZE;
             let texture_begin = texture_y * rect_width * FORMAT_SIZE;
             let texture_end = texture_begin + rect_width * FORMAT_SIZE;
-            self.texture.data[begin..end]
+            self.atlas_texture.data[begin..end]
                 .copy_from_slice(&texture.data[texture_begin..texture_end]);
         }
-        self.texture_allocations.push((texture_handle, allocation));
+
+        self.allocation_textures.insert(allocation.id, texture_handle);
+        self.texture_allocations.insert(texture_handle, allocation);
     }
 
     pub fn remove_texture(&mut self, texture_handle: Handle<Texture>) {
-        if let Some(position) = self.texture_allocations.iter().position(|(handle, _)| *handle == texture_handle) {
-            let (_, allocation) = self.texture_allocations.remove(position);
+        if let Some(allocation) = self.texture_allocations.remove(&texture_handle) {
+            self.allocation_textures.remove(&allocation.id);
             self.atlas_allocator.deallocate(allocation.id);
         }
     }
@@ -66,7 +115,7 @@ impl TextureAtlasBuilder {
         }
         TextureAtlas {
             dimensions: to_vec2(self.atlas_allocator.size()),
-            texture: textures.add(self.texture),
+            texture: textures.add(self.atlas_texture),
             textures: texture_rects,
             texture_handles: Some(texture_handles),
         }
@@ -85,4 +134,7 @@ impl From<guillotiere::Rectangle> for Rect {
 fn to_vec2(size: guillotiere::Size) -> Vec2 {
     Vec2::new(size.width as f32, size.height as f32)
 }
-    
+
+fn to_size2(vec2: Vec2) -> guillotiere::Size {
+    guillotiere::Size::new(vec2.x() as i32, vec2.y() as i32)
+}

examples/2d/texture_atlas.rs

@@ -42,37 +42,52 @@ fn load_atlas(
     asset_server: Res<AssetServer>,
     mut texture_atlases: ResMut<Assets<TextureAtlas>>,
     mut textures: ResMut<Assets<Texture>>,
+    mut materials: ResMut<Assets<ColorMaterial>>,
 ) {
     if state.atlas_loaded {
         return;
     }
 
-    let mut texture_atlas_builder = TextureAtlasBuilder::new(Vec2::new(600., 600.));
+    let mut texture_atlas_builder = TextureAtlasBuilder::default();
     if let Some(LoadState::Loaded(_)) =
         asset_server.get_group_load_state(&rpg_sprite_handles.handles)
     {
         // TODO: sort by size (within atlas builder)
         for texture_id in rpg_sprite_handles.handles.iter() {
             let handle = Handle::from_id(*texture_id);
-            let texture = textures.get(&handle).unwrap();
-            texture_atlas_builder.add_texture(handle, texture);
+            texture_atlas_builder.add_texture(handle, &textures);
         }
 
         let texture_atlas = texture_atlas_builder.finish(&mut textures);
+        let texture_atlas_texture= texture_atlas.texture;
         let vendor_handle = asset_server
             .get_handle("assets/textures/rpg/chars/vendor/generic-rpg-vendor.png")
             .unwrap();
         let vendor_index = texture_atlas.get_texture_index(vendor_handle).unwrap();
         let atlas_handle = texture_atlases.add(texture_atlas);
-        command_buffer.build().add_entity(SpriteSheetEntity {
-            sprite: TextureAtlasSprite {
-                index: vendor_index as u32,
-                scale: 4.0,
+        command_buffer
+            .build()
+            // draw a sprite from the atlas
+            .add_entity(SpriteSheetEntity {
+                sprite: TextureAtlasSprite {
+                    index: vendor_index as u32,
+                    scale: 4.0,
+                    position: Vec3::new(150.0, 0.0, 0.0),
+                    ..Default::default()
+                },
+                texture_atlas: atlas_handle,
                 ..Default::default()
-            },
-            texture_atlas: atlas_handle,
-            ..Default::default()
-        });
+            })
+            // draw the atlas itself
+            .add_entity(SpriteEntity {
+                material: materials.add(texture_atlas_texture.into()),
+                quad: Quad {
+                    position: Vec2::new(-300.0, 0.),
+                    ..Default::default()
+                },
+                sprite: Sprite { scale: 0.65 },
+                ..Default::default()
+            });
 
         state.atlas_loaded = true;
     }