Add ZIndex, YSort, and SortBias 2d components

Cargo.toml

@@ -778,6 +778,17 @@ description = "Renders an animated sprite"
 category = "2D Rendering"
 wasm = true
 
+[[example]]
+name = "sprite_sorting"
+path = "examples/2d/sprite_sorting.rs"
+doc-scrape-examples = true
+
+[package.metadata.example.sprite_sorting]
+name = "Sprite Sorting"
+description = "Demonstrates how to sort sprites"
+category = "2D Rendering"
+wasm = true
+
 [[example]]
 name = "sprite_tile"
 path = "examples/2d/sprite_tile.rs"

crates/bevy_core_pipeline/src/core_2d/mod.rs

@@ -343,9 +343,25 @@ impl CachedRenderPipelinePhaseItem for AlphaMask2d {
     }
 }
 
+#[derive(Debug, PartialOrd, Ord, PartialEq, Eq, Hash, Copy, Clone)]
+pub struct Transparent2dSortKey {
+    z_index: i32,
+    bias: FloatOrd,
+}
+
+impl Transparent2dSortKey {
+    pub fn new(z_index: i32, bias: Option<f32>) -> Transparent2dSortKey {
+        Transparent2dSortKey {
+            z_index,
+            // nans sort after any valid specified y sort
+            bias: FloatOrd(bias.unwrap_or(f32::NAN)),
+        }
+    }
+}
+
 /// Transparent 2D [`SortedPhaseItem`]s.
 pub struct Transparent2d {
-    pub sort_key: FloatOrd,
+    pub sort_key: Transparent2dSortKey,
     pub entity: (Entity, MainEntity),
     pub pipeline: CachedRenderPipelineId,
     pub draw_function: DrawFunctionId,
@@ -395,7 +411,7 @@ impl PhaseItem for Transparent2d {
 }
 
 impl SortedPhaseItem for Transparent2d {
-    type SortKey = FloatOrd;
+    type SortKey = Transparent2dSortKey;
 
     #[inline]
     fn sort_key(&self) -> Self::SortKey {
@@ -405,7 +421,7 @@ impl SortedPhaseItem for Transparent2d {
     #[inline]
     fn sort(items: &mut [Self]) {
         // radsort is a stable radix sort that performed better than `slice::sort_by_key` or `slice::sort_unstable_by_key`.
-        radsort::sort_by_key(items, |item| item.sort_key().0);
+        radsort::sort_by_key(items, |item| (item.sort_key.z_index, item.sort_key.bias.0));
     }
 
     fn indexed(&self) -> bool {

crates/bevy_gizmos/src/pipeline_2d.rs

@@ -6,7 +6,7 @@ use crate::{
 };
 use bevy_app::{App, Plugin};
 use bevy_asset::{load_embedded_asset, Handle};
-use bevy_core_pipeline::core_2d::{Transparent2d, CORE_2D_DEPTH_FORMAT};
+use bevy_core_pipeline::core_2d::{Transparent2d, Transparent2dSortKey, CORE_2D_DEPTH_FORMAT};
 
 use bevy_ecs::{
     prelude::Entity,
@@ -16,7 +16,6 @@ use bevy_ecs::{
     world::{FromWorld, World},
 };
 use bevy_image::BevyDefault as _;
-use bevy_math::FloatOrd;
 use bevy_render::sync_world::MainEntity;
 use bevy_render::{
     render_asset::{prepare_assets, RenderAssets},
@@ -343,7 +342,7 @@ fn queue_line_gizmos_2d(
                     entity: (entity, *main_entity),
                     draw_function,
                     pipeline,
-                    sort_key: FloatOrd(f32::INFINITY),
+                    sort_key: Transparent2dSortKey::new(i32::MAX, None),
                     batch_range: 0..1,
                     extra_index: PhaseItemExtraIndex::None,
                     extracted_index: usize::MAX,
@@ -365,7 +364,7 @@ fn queue_line_gizmos_2d(
                     entity: (entity, *main_entity),
                     draw_function: draw_function_strip,
                     pipeline,
-                    sort_key: FloatOrd(f32::INFINITY),
+                    sort_key: Transparent2dSortKey::new(i32::MAX, None),
                     batch_range: 0..1,
                     extra_index: PhaseItemExtraIndex::None,
                     extracted_index: usize::MAX,
@@ -425,7 +424,7 @@ fn queue_line_joint_gizmos_2d(
                 entity: (entity, *main_entity),
                 draw_function,
                 pipeline,
-                sort_key: FloatOrd(f32::INFINITY),
+                sort_key: Transparent2dSortKey::new(i32::MAX, None),
                 batch_range: 0..1,
                 extra_index: PhaseItemExtraIndex::None,
                 extracted_index: usize::MAX,

crates/bevy_sprite/src/mesh2d/material.rs

@@ -5,6 +5,7 @@ use crate::{
 use bevy_app::{App, Plugin, PostUpdate};
 use bevy_asset::prelude::AssetChanged;
 use bevy_asset::{AsAssetId, Asset, AssetApp, AssetEventSystems, AssetId, AssetServer, Handle};
+use bevy_core_pipeline::core_2d::Transparent2dSortKey;
 use bevy_core_pipeline::{
     core_2d::{
         AlphaMask2d, AlphaMask2dBinKey, BatchSetKey2d, Opaque2d, Opaque2dBinKey, Transparent2d,
@@ -18,7 +19,6 @@ use bevy_ecs::{
     prelude::*,
     system::{lifetimeless::SRes, SystemParamItem},
 };
-use bevy_math::FloatOrd;
 use bevy_platform::collections::HashMap;
 use bevy_reflect::{prelude::ReflectDefault, Reflect};
 use bevy_render::camera::extract_cameras;
@@ -839,7 +839,6 @@ pub fn queue_material2d_meshes<M: Material2d>(
             };
 
             mesh_instance.material_bind_group_id = material_2d.get_bind_group_id();
-            let mesh_z = mesh_instance.transforms.world_from_local.translation.z;
 
             // We don't support multidraw yet for 2D meshes, so we use this
             // custom logic to generate the `BinnedRenderPhaseType` instead of
@@ -852,8 +851,11 @@ pub fn queue_material2d_meshes<M: Material2d>(
                 BinnedRenderPhaseType::UnbatchableMesh
             };
 
-            match material_2d.properties.alpha_mode {
-                AlphaMode2d::Opaque => {
+            let needs_sort = mesh_instance.z_index.is_some()
+                || mesh_instance.y_sort
+                || mesh_instance.sort_bias.is_some();
+            match (material_2d.properties.alpha_mode, needs_sort) {
+                (AlphaMode2d::Opaque, false) => {
                     let bin_key = Opaque2dBinKey {
                         pipeline: pipeline_id,
                         draw_function: material_2d.properties.draw_function_id,
@@ -871,7 +873,7 @@ pub fn queue_material2d_meshes<M: Material2d>(
                         current_change_tick,
                     );
                 }
-                AlphaMode2d::Mask(_) => {
+                (AlphaMode2d::Mask(_), false) => {
                     let bin_key = AlphaMask2dBinKey {
                         pipeline: pipeline_id,
                         draw_function: material_2d.properties.draw_function_id,
@@ -889,7 +891,21 @@ pub fn queue_material2d_meshes<M: Material2d>(
                         current_change_tick,
                     );
                 }
-                AlphaMode2d::Blend => {
+                (AlphaMode2d::Blend, false) | (_, true) => {
+                    let mesh_y = mesh_instance.transforms.world_from_local.translation.y;
+                    let mesh_z = mesh_instance.transforms.world_from_local.translation.z;
+                    let z_bias = material_2d.properties.depth_bias;
+                    let sort_bias = mesh_instance.sort_bias;
+                    let bias = if mesh_instance.y_sort {
+                        mesh_y + z_bias + sort_bias.unwrap_or_default()
+                    } else {
+                        mesh_z + z_bias + sort_bias.unwrap_or_default()
+                    };
+
+                    let sort_key = Transparent2dSortKey::new(
+                        mesh_instance.z_index.unwrap_or_default(),
+                        Some(bias),
+                    );
                     transparent_phase.add(Transparent2d {
                         entity: (*render_entity, *visible_entity),
                         draw_function: material_2d.properties.draw_function_id,
@@ -898,7 +914,7 @@ pub fn queue_material2d_meshes<M: Material2d>(
                         // lowest sort key and getting closer should increase. As we have
                         // -z in front of the camera, the largest distance is -far with values increasing toward the
                         // camera. As such we can just use mesh_z as the distance
-                        sort_key: FloatOrd(mesh_z + material_2d.properties.depth_bias),
+                        sort_key,
                         // Batching is done in batch_and_prepare_render_phase
                         batch_range: 0..1,
                         extra_index: PhaseItemExtraIndex::None,

crates/bevy_sprite/src/mesh2d/mesh.rs

@@ -137,6 +137,26 @@ impl Plugin for Mesh2dRenderPlugin {
     }
 }
 
+/// Describes the layer in which the sprite or mesh should be rendered. Higher values are rendered
+/// on top of lower values, with a default value of 0. This is useful for controlling the rendering
+/// order of sprites and always takes precedence over [`YSort`] or [`SortBias`].
+#[derive(Component, Deref, DerefMut, Default, Debug, Clone)]
+pub struct ZIndex(pub i32);
+
+/// A marker component that enables Y-sorting (depth sorting) for sprites and meshes.
+///
+/// When attached to an entity, this component indicates that the entity should be rendered
+/// in draw order based on its Y position. Entities with lower Y values (higher on screen)
+/// are drawn first, creating a depth illusion where objects lower on the screen appear
+/// in front of objects higher on the screen.
+#[derive(Component, Default, Debug, Clone)]
+pub struct YSort;
+
+/// An arbitrary bias value that can be applied to the sorting order of sprites and meshes and is
+/// applied after the [`ZIndex`] or added to the Y position of the entity if [`YSort`] is enabled.
+#[derive(Component, Deref, DerefMut, Default, Debug, Clone)]
+pub struct SortBias(pub f32);
+
 #[derive(Resource, Deref, DerefMut, Default, Debug, Clone)]
 pub struct ViewKeyCache(MainEntityHashMap<Mesh2dPipelineKey>);
 
@@ -228,6 +248,9 @@ pub struct RenderMesh2dInstance {
     pub material_bind_group_id: Material2dBindGroupId,
     pub automatic_batching: bool,
     pub tag: u32,
+    pub z_index: Option<i32>,
+    pub y_sort: bool,
+    pub sort_bias: Option<f32>,
 }
 
 #[derive(Default, Resource, Deref, DerefMut)]
@@ -245,13 +268,27 @@ pub fn extract_mesh2d(
             &GlobalTransform,
             &Mesh2d,
             Option<&MeshTag>,
+            Option<&ZIndex>,
+            Has<YSort>,
+            Option<&SortBias>,
             Has<NoAutomaticBatching>,
         )>,
     >,
 ) {
     render_mesh_instances.clear();
 
-    for (entity, view_visibility, transform, handle, tag, no_automatic_batching) in &query {
+    for (
+        entity,
+        view_visibility,
+        transform,
+        handle,
+        tag,
+        z_index,
+        y_sort,
+        sort_bias,
+        no_automatic_batching,
+    ) in &query
+    {
         if !view_visibility.get() {
             continue;
         }
@@ -266,6 +303,9 @@ pub fn extract_mesh2d(
                 material_bind_group_id: Material2dBindGroupId::default(),
                 automatic_batching: !no_automatic_batching,
                 tag: tag.map_or(0, |i| **i),
+                z_index: z_index.cloned().map(|x| x.0),
+                y_sort,
+                sort_bias: sort_bias.cloned().map(|sb| sb.0),
             },
         );
     }

crates/bevy_sprite/src/render/mod.rs

@@ -1,8 +1,8 @@
-use core::ops::Range;
-
-use crate::{Anchor, ComputedTextureSlices, ScalingMode, Sprite};
+use crate::{Anchor, ComputedTextureSlices, ScalingMode, SortBias, Sprite, YSort, ZIndex};
 use bevy_asset::{load_embedded_asset, AssetEvent, AssetId, Assets, Handle};
+
 use bevy_color::{ColorToComponents, LinearRgba};
+use bevy_core_pipeline::core_2d::Transparent2dSortKey;
 use bevy_core_pipeline::{
     core_2d::{Transparent2d, CORE_2D_DEPTH_FORMAT},
     tonemapping::{
@@ -17,7 +17,7 @@ use bevy_ecs::{
     system::{lifetimeless::*, SystemParamItem, SystemState},
 };
 use bevy_image::{BevyDefault, Image, ImageSampler, TextureAtlasLayout, TextureFormatPixelInfo};
-use bevy_math::{Affine3A, FloatOrd, Quat, Rect, Vec2, Vec4};
+use bevy_math::{Affine3A, Quat, Rect, Vec2, Vec4};
 use bevy_platform::collections::HashMap;
 use bevy_render::view::{RenderVisibleEntities, RetainedViewEntity};
 use bevy_render::{
@@ -41,6 +41,7 @@ use bevy_render::{
 };
 use bevy_transform::components::GlobalTransform;
 use bytemuck::{Pod, Zeroable};
+use core::ops::Range;
 use fixedbitset::FixedBitSet;
 
 #[derive(Resource)]
@@ -343,6 +344,9 @@ pub struct ExtractedSprite {
     pub flip_x: bool,
     pub flip_y: bool,
     pub kind: ExtractedSpriteKind,
+    pub z_index: i32,
+    pub y_sort: bool,
+    pub sort_bias: Option<f32>,
 }
 
 pub enum ExtractedSpriteKind {
@@ -398,13 +402,26 @@ pub fn extract_sprites(
             &GlobalTransform,
             &Anchor,
             Option<&ComputedTextureSlices>,
+            Option<&ZIndex>,
+            Has<YSort>,
+            Option<&SortBias>,
         )>,
     >,
 ) {
     extracted_sprites.sprites.clear();
     extracted_slices.slices.clear();
-    for (main_entity, render_entity, view_visibility, sprite, transform, anchor, slices) in
-        sprite_query.iter()
+    for (
+        main_entity,
+        render_entity,
+        view_visibility,
+        sprite,
+        transform,
+        anchor,
+        slices,
+        z_index,
+        y_sort,
+        sort_bias,
+    ) in sprite_query.iter()
     {
         if !view_visibility.get() {
             continue;
@@ -427,6 +444,9 @@ pub fn extract_sprites(
                 kind: ExtractedSpriteKind::Slices {
                     indices: start..end,
                 },
+                z_index: z_index.cloned().map_or(0, |z| z.0),
+                y_sort,
+                sort_bias: sort_bias.cloned().map(|sb| sb.0),
             });
         } else {
             let atlas_rect = sprite
@@ -460,6 +480,9 @@ pub fn extract_sprites(
                     // Pass the custom size
                     custom_size: sprite.custom_size,
                 },
+                z_index: z_index.cloned().map_or(0, |z| z.0),
+                y_sort,
+                sort_bias: sort_bias.cloned().map(|sb| sb.0),
             });
         }
     }
@@ -595,7 +618,14 @@ pub fn queue_sprites(
             }
 
             // These items will be sorted by depth with other phase items
-            let sort_key = FloatOrd(extracted_sprite.transform.translation().z);
+            let sort_key = Transparent2dSortKey::new(
+                extracted_sprite.z_index,
+                extracted_sprite
+                    .y_sort
+                    .then_some(extracted_sprite.transform.translation().y)
+                    .map(|y| y + extracted_sprite.sort_bias.unwrap_or(0.0))
+                    .or(extracted_sprite.sort_bias),
+            );
 
             // Add the item to the render phase
             transparent_phase.add(Transparent2d {

crates/bevy_text/src/text2d.rs

@@ -238,6 +238,9 @@ pub fn extract_text2d_sprite(
                     kind: bevy_sprite::ExtractedSpriteKind::Slices {
                         indices: start..end,
                     },
+                    z_index: 0,
+                    y_sort: false,
+                    sort_bias: None,
                 });
                 start = end;
             }

examples/2d/2d_viewport_to_world.rs

@@ -183,6 +183,7 @@ fn setup(
     commands.spawn((
         Mesh2d(meshes.add(Rectangle::new(50000.0, 50000.0))),
         MeshMaterial2d(materials.add(Color::linear_rgb(0.01, 0.01, 0.01))),
-        Transform::from_translation(Vec3::new(0.0, 0.0, -200.0)),
+        Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)),
+        bevy::sprite::ZIndex(-1),
     ));
 }