fix font atlas overflow

crates/bevy_text/src/font_atlas.rs

@@ -39,15 +39,16 @@ impl FontAtlas {
         texture_atlases: &mut Assets<TextureAtlas>,
         character: char,
         texture: &Texture,
-    ) {
+    ) -> bool {
         let texture_atlas = texture_atlases.get_mut(&self.texture_atlas).unwrap();
         if let Some(index) =
             self.dynamic_texture_atlas_builder
                 .add_texture(texture_atlas, textures, texture)
         {
             self.glyph_to_index.insert(character, index);
+            true
         } else {
-            panic!("ran out of space in font atlas");
+            false
         }
     }
 }

crates/bevy_text/src/font_atlas_set.rs

@@ -13,7 +13,7 @@ type FontSizeKey = FloatOrd;
 #[derive(Default)]
 pub struct FontAtlasSet {
     font: Handle<Font>,
-    font_atlases: HashMap<FontSizeKey, FontAtlas>,
+    font_atlases: HashMap<FontSizeKey, Vec<FontAtlas>>,
 }
 
 #[derive(Debug)]
@@ -30,15 +30,17 @@ impl FontAtlasSet {
         }
     }
 
-    pub fn iter(&self) -> impl Iterator<Item = (&FontSizeKey, &FontAtlas)> {
+    pub fn iter(&self) -> impl Iterator<Item = (&FontSizeKey, &Vec<FontAtlas>)> {
         self.font_atlases.iter()
     }
 
     pub fn has_char(&self, character: char, font_size: f32) -> bool {
         self.font_atlases
             .get(&FloatOrd(font_size))
             .map_or(false, |font_atlas| {
-                font_atlas.get_char_index(character).is_some()
+                font_atlas
+                    .iter()
+                    .any(|atlas| atlas.get_char_index(character).is_some())
             })
     }
 
@@ -52,10 +54,16 @@ impl FontAtlasSet {
     ) -> f32 {
         let font = fonts.get(&self.font).unwrap();
         let scaled_font = ab_glyph::Font::as_scaled(&font.font, font_size);
-        let font_atlas = self
+        let font_atlases = self
             .font_atlases
             .entry(FloatOrd(font_size))
-            .or_insert_with(|| FontAtlas::new(textures, texture_atlases, Vec2::new(512.0, 512.0)));
+            .or_insert_with(|| {
+                vec![FontAtlas::new(
+                    textures,
+                    texture_atlases,
+                    Vec2::new(512.0, 512.0),
+                )]
+            });
 
         let mut last_glyph: Option<Glyph> = None;
         let mut width = 0.0;
@@ -67,10 +75,30 @@ impl FontAtlasSet {
             if let Some(last_glyph) = last_glyph.take() {
                 width += scaled_font.kern(last_glyph.id, glyph.id);
             }
-            if font_atlas.get_char_index(character).is_none() {
+            if !font_atlases
+                .iter()
+                .any(|atlas| atlas.get_char_index(character).is_some())
+            {
                 if let Some(outlined_glyph) = scaled_font.outline_glyph(glyph.clone()) {
                     let glyph_texture = Font::get_outlined_glyph_texture(outlined_glyph);
-                    font_atlas.add_char(textures, texture_atlases, character, &glyph_texture);
+                    let add_char_to_font_atlas = |atlas: &mut FontAtlas| -> bool {
+                        atlas.add_char(textures, texture_atlases, character, &glyph_texture)
+                    };
+                    if !font_atlases.iter_mut().any(add_char_to_font_atlas) {
+                        font_atlases.push(FontAtlas::new(
+                            textures,
+                            texture_atlases,
+                            Vec2::new(512.0, 512.0),
+                        ));
+                        if !font_atlases.last_mut().unwrap().add_char(
+                            textures,
+                            texture_atlases,
+                            character,
+                            &glyph_texture,
+                        ) {
+                            panic!("could not add character to newly created FontAtlas");
+                        }
+                    }
                 }
             }
             width += scaled_font.h_advance(glyph.id);
@@ -85,9 +113,14 @@ impl FontAtlasSet {
             .get(&FloatOrd(font_size))
             .and_then(|font_atlas| {
                 font_atlas
-                    .get_char_index(character)
-                    .map(|char_index| GlyphAtlasInfo {
-                        texture_atlas: font_atlas.texture_atlas,
+                    .iter()
+                    .find_map(|atlas| {
+                        atlas
+                            .get_char_index(character)
+                            .map(|char_index| (char_index, atlas.texture_atlas))
+                    })
+                    .map(|(char_index, texture_atlas)| GlyphAtlasInfo {
+                        texture_atlas,
                         char_index,
                     })
             })

examples/ui/font_atlas_debug.rs

@@ -12,15 +12,15 @@ fn main() {
 }
 
 struct State {
-    added: bool,
+    atlas_count: u32,
     handle: Handle<Font>,
     timer: Timer,
 }
 
 impl Default for State {
     fn default() -> Self {
         Self {
-            added: false,
+            atlas_count: 0,
             handle: Handle::default(),
             timer: Timer::from_seconds(0.05, true),
         }
@@ -34,20 +34,23 @@ fn atlas_render_system(
     font_atlas_sets: Res<Assets<FontAtlasSet>>,
     texture_atlases: Res<Assets<TextureAtlas>>,
 ) {
-    if state.added {
-        return;
-    }
     if let Some(set) = font_atlas_sets.get(&state.handle.as_handle::<FontAtlasSet>()) {
         if let Some((_size, font_atlas)) = set.iter().next() {
-            state.added = true;
-            let texture_atlas = texture_atlases.get(&font_atlas.texture_atlas).unwrap();
+            let x_offset = state.atlas_count as f32;
+            if state.atlas_count == font_atlas.len() as u32 {
+                return;
+            }
+            let texture_atlas = texture_atlases
+                .get(&font_atlas[state.atlas_count as usize].texture_atlas)
+                .unwrap();
+            state.atlas_count += 1;
             commands.spawn(ImageComponents {
                 material: materials.add(texture_atlas.texture.into()),
                 style: Style {
                     position_type: PositionType::Absolute,
                     position: Rect {
                         top: Val::Px(0.0),
-                        left: Val::Px(0.0),
+                        left: Val::Px(512.0 * x_offset),
                         ..Default::default()
                     },
                     ..Default::default()
@@ -61,8 +64,9 @@ fn atlas_render_system(
 fn text_update_system(mut state: ResMut<State>, time: Res<Time>, mut query: Query<&mut Text>) {
     for mut text in &mut query.iter() {
         state.timer.tick(time.delta_seconds);
-        if state.timer.finished {
-            text.value = format!("{}", rand::random::<u8>() as char);
+        let c = rand::random::<u8>() as char;
+        if !text.value.contains(c) && state.timer.finished {
+            text.value = format!("{}{}", text.value, c);
             state.timer.reset();
         }
     }