Implement rotation for Text2d

Author: nside

crates/bevy_text/src/draw.rs

@@ -1,4 +1,6 @@
+use crate::{PositionedGlyph, TextSection};
 use bevy_math::{Mat4, Vec3};
+use bevy_render::pipeline::IndexFormat;
 use bevy_render::{
     draw::{Draw, DrawContext, DrawError, Drawable},
     mesh,
@@ -8,19 +10,18 @@ use bevy_render::{
     renderer::{BindGroup, RenderResourceBindings, RenderResourceId},
 };
 use bevy_sprite::TextureAtlasSprite;
+use bevy_transform::prelude::GlobalTransform;
 use bevy_utils::tracing::error;
 
-use crate::{PositionedGlyph, TextSection};
-use bevy_render::pipeline::IndexFormat;
-
 pub struct DrawableText<'a> {
     pub render_resource_bindings: &'a mut RenderResourceBindings,
-    pub position: Vec3,
+    pub global_transform: GlobalTransform,
     pub scale_factor: f32,
     pub sections: &'a [TextSection],
     pub text_glyphs: &'a Vec<PositionedGlyph>,
     pub msaa: &'a Msaa,
     pub font_quad_vertex_layout: &'a VertexBufferLayout,
+    pub alignment_offset: Vec3,
 }
 
 impl<'a> Drawable for DrawableText<'a> {
@@ -76,20 +77,12 @@ impl<'a> Drawable for DrawableText<'a> {
                 flip_y: false,
             };
 
-            // To get the rendering right for non-one scaling factors, we need
-            // the sprite to be drawn in "physical" coordinates. This is because
-            // the shader uses the size of the sprite to control the size on
-            // screen. To accomplish this we make the sprite transform
-            // convert from physical coordinates to logical coordinates in
-            // addition to altering the origin. Since individual glyphs will
-            // already be in physical coordinates, we just need to convert the
-            // overall position to physical coordinates to get the sprites
-            // physical position.
-
-            let transform = Mat4::from_scale(Vec3::splat(1. / self.scale_factor))
-                * Mat4::from_translation(
-                    self.position * self.scale_factor + tv.position.extend(0.),
-                );
+            let scale_transform = Mat4::from_scale(Vec3::splat(1. / self.scale_factor));
+            let transform = Mat4::from_rotation_translation(
+                self.global_transform.rotation,
+                self.global_transform.translation,
+            ) * scale_transform
+                * Mat4::from_translation(self.alignment_offset + tv.position.extend(0.));
 
             let transform_buffer = context.get_uniform_buffer(&transform).unwrap();
             let sprite_buffer = context.get_uniform_buffer(&sprite).unwrap();

crates/bevy_text/src/text2d.rs

@@ -92,26 +92,25 @@ pub fn draw_text2d_system(
         let (width, height) = (calculated_size.size.width, calculated_size.size.height);
 
         if let Some(text_glyphs) = text_pipeline.get_glyphs(&entity) {
-            let position = global_transform.translation
-                + match text.alignment.vertical {
-                    VerticalAlign::Top => Vec3::ZERO,
-                    VerticalAlign::Center => Vec3::new(0.0, -height * 0.5, 0.0),
-                    VerticalAlign::Bottom => Vec3::new(0.0, -height, 0.0),
-                }
-                + match text.alignment.horizontal {
-                    HorizontalAlign::Left => Vec3::new(-width, 0.0, 0.0),
-                    HorizontalAlign::Center => Vec3::new(-width * 0.5, 0.0, 0.0),
-                    HorizontalAlign::Right => Vec3::ZERO,
-                };
+            let alignment_offset = match text.alignment.vertical {
+                VerticalAlign::Top => Vec3::ZERO,
+                VerticalAlign::Center => Vec3::new(0.0, -height * 0.5, 0.0),
+                VerticalAlign::Bottom => Vec3::new(0.0, -height, 0.0),
+            } + match text.alignment.horizontal {
+                HorizontalAlign::Left => Vec3::new(-width, 0.0, 0.0),
+                HorizontalAlign::Center => Vec3::new(-width * 0.5, 0.0, 0.0),
+                HorizontalAlign::Right => Vec3::ZERO,
+            };
 
             let mut drawable_text = DrawableText {
                 render_resource_bindings: &mut render_resource_bindings,
-                position,
+                global_transform: *global_transform,
+                scale_factor,
                 msaa: &msaa,
                 text_glyphs: &text_glyphs.glyphs,
                 font_quad_vertex_layout: &font_quad_vertex_layout,
-                scale_factor,
                 sections: &text.sections,
+                alignment_offset: alignment_offset * scale_factor,
             };
 
             drawable_text.draw(&mut draw, &mut context).unwrap();

crates/bevy_ui/src/widget/text.rs

@@ -167,16 +167,15 @@ pub fn draw_text_system(
         }
 
         if let Some(text_glyphs) = text_pipeline.get_glyphs(&entity) {
-            let position = global_transform.translation - (node.size / 2.0).extend(0.0);
-
             let mut drawable_text = DrawableText {
                 render_resource_bindings: &mut render_resource_bindings,
-                position,
+                global_transform: *global_transform,
                 scale_factor: scale_factor as f32,
                 msaa: &msaa,
                 text_glyphs: &text_glyphs.glyphs,
                 font_quad_vertex_layout: &vertex_buffer_layout,
                 sections: &text.sections,
+                alignment_offset: (node.size / -2.0).extend(0.0) * (scale_factor as f32),
             };
 
             drawable_text.draw(&mut draw, &mut context).unwrap();

examples/2d/text2d.rs

@@ -30,10 +30,11 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
 
 fn animate(time: Res<Time>, mut query: Query<&mut Transform, With<Text>>) {
     // `Transform.translation` will determine the location of the text.
-    // `Transform.scale` and `Transform.rotation` do not yet affect text (though you can set the
-    // size of the text via `Text.style.font_size`)
+    // `Transform.scale` (though you can set the size of the text via
+    // `Text.style.font_size`)
     for mut transform in query.iter_mut() {
         transform.translation.x = 100.0 * time.seconds_since_startup().sin() as f32;
         transform.translation.y = 100.0 * time.seconds_since_startup().cos() as f32;
+        transform.rotation = Quat::from_rotation_z(time.seconds_since_startup().cos() as f32);
     }
 }