text: new atlased rendering finally works!

removed old render-to-texture rendering

crates/bevy_asset/src/handle.rs

@@ -37,6 +37,10 @@ impl<T> Handle<T> {
         }
     }
 
+    /// Gets a handle for the given type that has this handle's id. This is useful when an
+    /// asset is derived from another asset. In this case, a common handle can be used to
+    /// correlate them.
+    /// NOTE: This pattern might eventually be replaced by a more formal asset dependency system.
     pub fn as_handle<U>(&self) -> Handle<U> {
         Handle::from_id(self.id)
     }

crates/bevy_sprite/src/render/sprite_sheet.vert

@@ -6,9 +6,16 @@ layout(location = 2) in vec2 Vertex_Uv;
 
 layout(location = 0) out vec2 v_Uv;
 
+// TODO: remove UI shader def and replace with generic "Camera" when its easier to manually bind global RenderResourceBindings 
+#ifdef UI_CAMERA
+layout(set = 0, binding = 0) uniform UiCamera {
+    mat4 ViewProj;
+};
+# else
 layout(set = 0, binding = 0) uniform Camera2d {
     mat4 ViewProj;
 };
+#endif
 
 // TODO: merge dimensions into "sprites" buffer when that is supported in the Uniforms derive abstraction
 layout(set = 1, binding = 0) uniform TextureAtlas_size {

crates/bevy_text/src/draw.rs

@@ -1,9 +1,10 @@
 use crate::{Font, FontAtlasSet};
+use ab_glyph::{Glyph, PxScale, ScaleFont};
 use bevy_asset::Assets;
 use bevy_render::{
     draw::{Draw, DrawContext, DrawError, Drawable},
     mesh,
-    pipeline::PipelineSpecialization,
+    pipeline::{PipelineSpecialization, ShaderSpecialization},
     render_resource::{
         AssetRenderResourceBindings, BindGroup, BufferUsage, RenderResourceBindings,
         RenderResourceId,
@@ -12,13 +13,13 @@ use bevy_render::{
 };
 use bevy_sprite::{TextureAtlas, TextureAtlasSprite};
 use glam::Vec3;
+use std::collections::HashSet;
 
 pub struct TextStyle {
     pub font_size: f32,
     pub color: Color,
 }
 
-#[allow(dead_code)]
 pub struct DrawableText<'a> {
     font: &'a Font,
     font_atlas_set: &'a FontAtlasSet,
@@ -56,10 +57,16 @@ impl<'a> DrawableText<'a> {
 
 impl<'a> Drawable for DrawableText<'a> {
     fn draw(&mut self, draw: &mut Draw, context: &mut DrawContext) -> Result<(), DrawError> {
+        let mut shader_defs = HashSet::new();
+        shader_defs.insert("UI_CAMERA".to_string());
         context.set_pipeline(
             draw,
             bevy_sprite::SPRITE_SHEET_PIPELINE_HANDLE,
-            PipelineSpecialization::empty(),
+            // TODO: remove this shader def specialization when its easier to manually bind global render resources to specific bind groups
+            &PipelineSpecialization {
+                shader_specialization: ShaderSpecialization { shader_defs },
+                ..Default::default()
+            },
         )?;
 
         let render_resource_context = &**context.render_resource_context;
@@ -80,25 +87,57 @@ impl<'a> Drawable for DrawableText<'a> {
             }
         }
 
-        let current_position = Vec3::new(0.0, 0.0, 0.0);
         // set global bindings
         context.set_bind_groups_from_bindings(draw, &mut [self.render_resource_bindings])?;
 
+        // NOTE: this uses ab_glyph apis directly. it _might_ be a good idea to add our own layer on top
+        let font = &self.font.font;
+        let scale = PxScale::from(self.style.font_size);
+        let scaled_font = ab_glyph::Font::as_scaled(&font, scale);
+        let mut caret = self.position;
+        let mut last_glyph: Option<Glyph> = None;
+
         // set local per-character bindings
         for character in self.text.chars() {
+            if character.is_control() {
+                continue;
+            }
+
+            let glyph = scaled_font.scaled_glyph(character);
+            if let Some(last_glyph) = last_glyph.take() {
+                caret.set_x(caret.x() + scaled_font.kern(last_glyph.id, glyph.id));
+            }
             if let Some(glyph_atlas_info) = self
                 .font_atlas_set
                 .get_glyph_atlas_info(self.style.font_size, character)
             {
+                if let Some(outlined) = scaled_font.outline_glyph(glyph.clone()) {
+                    let texture_atlas = self
+                        .texture_atlases
+                        .get(&glyph_atlas_info.texture_atlas)
+                        .unwrap();
+                    let glyph_rect = texture_atlas.textures[glyph_atlas_info.char_index as usize];
+                    let glyph_width = glyph_rect.width();
+                    let glyph_height = glyph_rect.height();
                     let atlas_render_resource_bindings = self
                         .asset_render_resource_bindings
                         .get_mut(glyph_atlas_info.texture_atlas)
                         .unwrap();
-                context
+                    context.set_bind_groups_from_bindings(
-                    .set_bind_groups_from_bindings(draw, &mut [atlas_render_resource_bindings])?;
+                        draw,
+                        &mut [atlas_render_resource_bindings],
+                    )?;
+
+                    let bounds = outlined.px_bounds();
+                    let offset = scaled_font.descent() + glyph_height;
                     let sprite_buffer = TextureAtlasSprite {
                         index: glyph_atlas_info.char_index,
-                    position: current_position,
+                        position: caret
+                            + Vec3::new(
+                                0.0 + glyph_width / 2.0 + bounds.min.x,
+                                glyph_height / 2.0 - bounds.min.y - offset,
+                                0.0,
+                            ),
                         scale: 1.0,
                     };
 
@@ -106,12 +145,16 @@ impl<'a> Drawable for DrawableText<'a> {
                         .shared_buffers
                         .get_buffer(&sprite_buffer, BufferUsage::UNIFORM)
                         .unwrap();
-                let sprite_bind_group = BindGroup::build().add_binding(0, sprite_buffer).finish();
+                    let sprite_bind_group =
+                        BindGroup::build().add_binding(0, sprite_buffer).finish();
                     context.create_bind_group_resource(2, &sprite_bind_group)?;
                     draw.set_bind_group(2, &sprite_bind_group);
                     draw.draw_indexed(indices.clone(), 0, 0..1);
                 }
             }
+            caret.set_x(caret.x() + scaled_font.h_advance(glyph.id));
+            last_glyph = Some(glyph);
+        }
         Ok(())
     }
 }

crates/bevy_ui/src/entity.rs

@@ -18,12 +18,12 @@ pub struct UiEntity {
 impl Default for UiEntity {
     fn default() -> Self {
         UiEntity {
+            mesh: QUAD_HANDLE,
+            render_pipelines: RenderPipelines::from_handles(&[UI_PIPELINE_HANDLE]),
             node: Default::default(),
             quad: Default::default(),
-            mesh: QUAD_HANDLE,
             material: Default::default(),
             draw: Default::default(),
-            render_pipelines: RenderPipelines::from_handles(&[UI_PIPELINE_HANDLE]),
         }
     }
 }
@@ -32,24 +32,17 @@ impl Default for UiEntity {
 pub struct LabelEntity {
     pub node: Node,
     pub quad: Quad,
-    pub mesh: Handle<Mesh>, // TODO: maybe abstract this out
-    pub material: Handle<ColorMaterial>,
     pub draw: Draw,
-    pub render_pipelines: RenderPipelines,
     pub label: Label,
 }
 
 impl Default for LabelEntity {
     fn default() -> Self {
         LabelEntity {
+            label: Label::default(),
             node: Default::default(),
             quad: Default::default(),
-            mesh: QUAD_HANDLE,
-            // NOTE: labels each get their own material.
-            material: Handle::new(), // TODO: maybe abstract this out
             draw: Default::default(),
-            render_pipelines: RenderPipelines::from_handles(&[UI_PIPELINE_HANDLE]),
-            label: Label::default(),
         }
     }
 }

crates/bevy_ui/src/widget/label.rs

@@ -5,10 +5,10 @@ use bevy_render::{
     texture::Texture,
     Color,
 };
-use bevy_sprite::{ColorMaterial, ComMut, Quad, TextureAtlas};
+use bevy_sprite::{ComMut, Quad, TextureAtlas};
 use bevy_text::{DrawableText, Font, FontAtlasSet, TextStyle};
-use legion::prelude::{Com, Res, ResMut};
 use glam::Vec3;
+use legion::prelude::{Com, Res, ResMut};
 
 pub struct Label {
     pub text: String,
@@ -32,24 +32,22 @@ impl Default for Label {
 impl Label {
     // PERF: this is horrendously inefficient. (1) new texture per label per frame (2) no atlas
     pub fn label_system(
-        mut color_materials: ResMut<Assets<ColorMaterial>>,
         mut textures: ResMut<Assets<Texture>>,
         fonts: Res<Assets<Font>>,
         mut font_atlas_sets: ResMut<Assets<FontAtlasSet>>,
         mut texture_atlases: ResMut<Assets<TextureAtlas>>,
         label: Com<Label>,
-        quad: Com<Quad>,
-        color_material_handle: Com<Handle<ColorMaterial>>,
     ) {
-        // ensure the texture is at least 1x1
-        let width = quad.size.x().max(1.0);
-        let height = quad.size.y().max(1.0);
-
-        if let Some(font) = fonts.get(&label.font) {
         let font_atlases = font_atlas_sets
             .get_or_insert_with(Handle::from_id(label.font.id), || {
                 FontAtlasSet::new(label.font)
             });
+        // TODO: this call results in one or more TextureAtlases, whose render resources are created in the RENDER_GRAPH_SYSTEMS
+        // stage. That logic runs _before_ the DRAW stage, which means we cant call add_glyphs_to_atlas in the draw stage
+        // without or render resources being a frame behind. Therefore glyph atlasing either needs its own system or the TextureAtlas
+        // resource generation needs to happen AFTER the render graph systems. maybe draw systems should execute within the
+        // render graph so ordering like this can be taken into account? Maybe the RENDER_GRAPH_SYSTEMS stage should be removed entirely
+        // in favor of node.update()? Regardless, in the immediate short term the current approach is fine.
         font_atlases.add_glyphs_to_atlas(
             &fonts,
             &mut texture_atlases,
@@ -57,21 +55,6 @@ impl Label {
             label.style.font_size,
             &label.text,
         );
-
-            let material = color_materials.get_or_insert_with(*color_material_handle, || {
-                ColorMaterial::from(Handle::<Texture>::new())
-            });
-
-            let texture = font.render_text(
-                &label.text,
-                label.style.color,
-                label.style.font_size,
-                width as usize,
-                height as usize,
-            );
-
-            material.texture = Some(textures.add(texture));
-        }
     }
 
     pub fn draw_label_system(
@@ -85,6 +68,7 @@ impl Label {
         label: Com<Label>,
         quad: Com<Quad>,
     ) {
+        let position = quad.position - quad.size / 2.0;
         let mut drawable_text = DrawableText::new(
             fonts.get(&label.font).unwrap(),
             font_atlas_sets
@@ -93,7 +77,7 @@ impl Label {
             &texture_atlases,
             &mut render_resource_bindings,
             &mut asset_render_resource_bindings,
-            Vec3::new(quad.position.x(), quad.position.y(), 0.0),
+            Vec3::new(position.x(), position.y(), 0.0),
             &label.style,
             &label.text,
         );

examples/ui/text.rs

@@ -15,7 +15,7 @@ fn main() {
 fn text_update_system(diagnostics: Res<Diagnostics>, mut label: ComMut<Label>) {
     if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
         if let Some(average) = fps.average() {
-            label.text = format!("FPS: {}", average);
+            label.text = format!("FPS: {:.2}", average);
         }
     }
 }
@@ -25,7 +25,6 @@ fn setup(command_buffer: &mut CommandBuffer, asset_server: Res<AssetServer>) {
     command_buffer
         .build()
         // 2d camera
-        .add_entity(OrthographicCameraEntity::default())
         .add_entity(OrthographicCameraEntity::ui())
         // texture
         .add_entity(LabelEntity {