bevy_ui_render/

ui_texture_slice_pipeline.rs

use core::{hash::Hash, ops::Range};

use crate::clipping::clip_polygon;
use crate::*;
use bevy_asset::*;
use bevy_color::{ColorToComponents, LinearRgba};
use bevy_ecs::{
    prelude::Component,
    system::{
        lifetimeless::{Read, SRes},
        *,
    },
};
use bevy_image::prelude::*;
use bevy_math::{Affine2, FloatOrd, Rect, Vec2};
use bevy_mesh::VertexBufferLayout;
use bevy_platform::collections::HashMap;
use bevy_render::{
    render_asset::RenderAssets,
    render_phase::*,
    render_resource::{binding_types::uniform_buffer, *},
    renderer::{RenderDevice, RenderQueue},
    texture::GpuImage,
    view::*,
    Extract, ExtractSchedule, Render, RenderSystems,
};
use bevy_render::{sync_world::MainEntity, GpuResourceAppExt, RenderStartup};
use bevy_shader::Shader;
use bevy_sprite::{SliceScaleMode, SpriteImageMode, TextureSlicer};
use bevy_sprite_render::SpriteAssetEvents;
use bevy_ui::widget::NodeImageMode;
use bevy_ui::{ComputedStackIndex, VisualBox};
use bevy_utils::default;
use binding_types::{sampler, texture_2d};
use bytemuck::{Pod, Zeroable};

pub struct UiTextureSlicerPlugin;

impl Plugin for UiTextureSlicerPlugin {
    fn build(&self, app: &mut App) {
        embedded_asset!(app, "ui_texture_slice.wesl");

        if let Some(render_app) = app.get_sub_app_mut(RenderApp) {
            render_app
                .add_render_command::<TransparentUi, DrawUiTextureSlices>()
                .init_resource::<ExtractedUiTextureSlices>()
                .init_gpu_resource::<UiTextureSliceMeta>()
                .init_gpu_resource::<UiTextureSliceImageBindGroups>()
                .init_gpu_resource::<SpecializedRenderPipelines<UiTextureSlicePipeline>>()
                .add_systems(RenderStartup, init_ui_texture_slice_pipeline)
                .add_systems(
                    ExtractSchedule,
                    extract_ui_texture_slices.in_set(RenderUiSystems::ExtractTextureSlice),
                )
                .add_systems(
                    Render,
                    (
                        queue_ui_slices.in_set(RenderSystems::Queue),
                        prepare_ui_slices.in_set(RenderSystems::PrepareBindGroups),
                    ),
                );
        }
    }
}

#[repr(C)]
#[derive(Copy, Clone, Pod, Zeroable)]
struct UiTextureSliceVertex {
    pub position: [f32; 3],
    pub uv: [f32; 2],
    pub color: [f32; 4],
    pub slices: [f32; 4],
    pub border: [f32; 4],
    pub repeat: [f32; 4],
    pub atlas: [f32; 4],
}

#[derive(Component)]
pub struct UiTextureSlicerBatch {
    pub range: Range<u32>,
    pub image: AssetId<Image>,
}

#[derive(Resource)]
pub struct UiTextureSliceMeta {
    vertices: RawBufferVec<UiTextureSliceVertex>,
    indices: RawBufferVec<u32>,
    view_bind_group: Option<BindGroup>,
}

impl Default for UiTextureSliceMeta {
    fn default() -> Self {
        Self {
            vertices: RawBufferVec::new(BufferUsages::VERTEX),
            indices: RawBufferVec::new(BufferUsages::INDEX),
            view_bind_group: None,
        }
    }
}

#[derive(Resource, Default)]
pub struct UiTextureSliceImageBindGroups {
    pub values: HashMap<AssetId<Image>, BindGroup>,
}

#[derive(Resource)]
pub struct UiTextureSlicePipeline {
    pub view_layout: BindGroupLayoutDescriptor,
    pub image_layout: BindGroupLayoutDescriptor,
    pub shader: Handle<Shader>,
}

pub fn init_ui_texture_slice_pipeline(mut commands: Commands, asset_server: Res<AssetServer>) {
    let view_layout = BindGroupLayoutDescriptor::new(
        "ui_texture_slice_view_layout",
        &BindGroupLayoutEntries::single(
            ShaderStages::VERTEX_FRAGMENT,
            uniform_buffer::<ViewUniform>(true),
        ),
    );

    let image_layout = BindGroupLayoutDescriptor::new(
        "ui_texture_slice_image_layout",
        &BindGroupLayoutEntries::sequential(
            ShaderStages::FRAGMENT,
            (
                texture_2d(TextureSampleType::Float { filterable: true }),
                sampler(SamplerBindingType::Filtering),
            ),
        ),
    );

    commands.insert_resource(UiTextureSlicePipeline {
        view_layout,
        image_layout,
        shader: load_embedded_asset!(asset_server.as_ref(), "ui_texture_slice.wesl"),
    });
}

#[derive(Clone, Copy, Hash, PartialEq, Eq)]
pub struct UiTextureSlicePipelineKey {
    pub target_format: TextureFormat,
}

impl SpecializedRenderPipeline for UiTextureSlicePipeline {
    type Key = UiTextureSlicePipelineKey;

    fn specialize(&self, key: Self::Key) -> RenderPipelineDescriptor {
        let vertex_layout = VertexBufferLayout::from_vertex_formats(
            VertexStepMode::Vertex,
            vec![
                // position
                VertexFormat::Float32x3,
                // uv
                VertexFormat::Float32x2,
                // color
                VertexFormat::Float32x4,
                // normalized texture slicing lines (left, top, right, bottom)
                VertexFormat::Float32x4,
                // normalized target slicing lines (left, top, right, bottom)
                VertexFormat::Float32x4,
                // repeat values (horizontal side, vertical side, horizontal center, vertical center)
                VertexFormat::Float32x4,
                // normalized texture atlas rect (left, top, right, bottom)
                VertexFormat::Float32x4,
            ],
        );
        let shader_defs = Vec::new();

        RenderPipelineDescriptor {
            vertex: VertexState {
                shader: self.shader.clone(),
                shader_defs: shader_defs.clone(),
                buffers: vec![vertex_layout],
                ..default()
            },
            fragment: Some(FragmentState {
                shader: self.shader.clone(),
                shader_defs,
                targets: vec![Some(ColorTargetState {
                    format: key.target_format,
                    blend: Some(BlendState::ALPHA_BLENDING),
                    write_mask: ColorWrites::ALL,
                })],
                ..default()
            }),
            layout: vec![self.view_layout.clone(), self.image_layout.clone()],
            label: Some("ui_texture_slice_pipeline".into()),
            ..default()
        }
    }
}

pub struct ExtractedUiTextureSlice {
    pub stack_index: u32,
    pub transform: Affine2,
    pub rect: Rect,
    pub atlas_rect: Option<Rect>,
    pub image: AssetId<Image>,
    pub clip: Option<CalculatedClip>,
    pub color: LinearRgba,
    pub image_scale_mode: SpriteImageMode,
    pub flip_x: bool,
    pub flip_y: bool,
    pub inverse_scale_factor: f32,
}

/// A render-world resource that stores all texture slices in the scene.
#[derive(Resource, Default)]
pub struct ExtractedUiTextureSlices {
    /// The list of texture slices grouped by their main-world entity, along with
    /// each group's target camera entity.
    ///
    /// This is a two-level data structure so that we can quickly remove all
    /// texture slices associated with a main-world entity when it changes.
    pub slices: MainEntityHashMap<(Entity, EntityIndexMap<ExtractedUiTextureSlice>)>,
}

pub fn extract_ui_texture_slices(
    mut commands: Commands,
    mut extracted_ui_slicers: ResMut<ExtractedUiTextureSlices>,
    texture_atlases: Extract<Res<Assets<TextureAtlasLayout>>>,
    slicers_query: Extract<
        Query<
            (
                Entity,
                &ComputedNode,
                &ComputedStackIndex,
                &UiGlobalTransform,
                &InheritedVisibility,
                Option<&CalculatedClip>,
                &ComputedUiTargetCamera,
                &ImageNode,
            ),
            Or<(
                Changed<ComputedNode>,
                Changed<ComputedStackIndex>,
                Changed<UiGlobalTransform>,
                Changed<InheritedVisibility>,
                Changed<CalculatedClip>,
                Changed<ComputedUiTargetCamera>,
                Changed<ImageNode>,
                // The `bevy_ui::widget::update_image_content_size_system` marks
                // `ImageNodeSize` as changed to indicate that the image metrics
                // and/or texture atlas layout changed, so we need to watch for
                // changes to that component, even though we don't read it.
                Changed<ImageNodeSize>,
            )>,
        >,
    >,
    unfiltered_slicers_query: Extract<
        Query<(
            Entity,
            &ComputedNode,
            &ComputedStackIndex,
            &UiGlobalTransform,
            &InheritedVisibility,
            Option<&CalculatedClip>,
            &ComputedUiTargetCamera,
            &ImageNode,
        )>,
    >,
    camera_map: Extract<UiCameraMap>,
    (
        mut removed_computed_node_query,
        mut removed_computed_stack_index_query,
        mut removed_ui_global_transform_query,
        mut removed_inherited_visibility_query,
        mut removed_calculated_clip_query,
        mut removed_computed_ui_target_camera_query,
        mut removed_image_node_query,
    ): (
        Extract<RemovedComponents<ComputedNode>>,
        Extract<RemovedComponents<ComputedStackIndex>>,
        Extract<RemovedComponents<UiGlobalTransform>>,
        Extract<RemovedComponents<InheritedVisibility>>,
        Extract<RemovedComponents<CalculatedClip>>,
        Extract<RemovedComponents<ComputedUiTargetCamera>>,
        Extract<RemovedComponents<ImageNode>>,
    ),
    mut nodes_processed_this_frame: Local<MainEntityHashSet>,
) {
    nodes_processed_this_frame.clear();
    let mut camera_mapper = camera_map.get_mapper();

    for (entity, uinode, stack_index, transform, inherited_visibility, clip, camera, image) in
        slicers_query.iter().chain(
            removed_calculated_clip_query
                .read()
                .filter_map(|entity| unfiltered_slicers_query.get(entity).ok()),
        )
    {
        let main_entity = MainEntity::from(entity);

        // If there were any previous UI slices for this entity, despawn them.
        for (render_entity, _) in extracted_ui_slicers
            .slices
            .get_mut(&main_entity)
            .iter_mut()
            .flat_map(|(_, slices)| slices.drain(..))
        {
            commands.entity(render_entity).despawn();
        }

        let visual_box = match image.visual_box {
            VisualBox::ContentBox => uinode.content_box(),
            VisualBox::PaddingBox => uinode.padding_box(),
            VisualBox::BorderBox => uinode.border_box(),
        };

        // Skip invisible images
        if !inherited_visibility.get()
            || image.color.is_fully_transparent()
            || image.image.id() == TRANSPARENT_IMAGE_HANDLE.id()
            || visual_box.size().cmple(Vec2::ZERO).any()
        {
            continue;
        }

        let image_scale_mode = match image.image_mode.clone() {
            NodeImageMode::Sliced(texture_slicer) => SpriteImageMode::Sliced(texture_slicer),
            NodeImageMode::Tiled {
                tile_x,
                tile_y,
                stretch_value,
            } => SpriteImageMode::Tiled {
                tile_x,
                tile_y,
                stretch_value,
            },
            _ => continue,
        };

        let Some(extracted_camera_entity) = camera_mapper.map(camera) else {
            continue;
        };
        if let Some((camera_entity, _)) = extracted_ui_slicers.slices.get_mut(&main_entity) {
            *camera_entity = extracted_camera_entity;
        }

        nodes_processed_this_frame.insert(main_entity);

        let atlas_rect = image
            .texture_atlas
            .as_ref()
            .and_then(|s| s.texture_rect(&texture_atlases))
            .map(|r| r.as_rect());

        let atlas_rect = match (atlas_rect, image.rect) {
            (None, None) => None,
            (None, Some(image_rect)) => Some(image_rect),
            (Some(atlas_rect), None) => Some(atlas_rect),
            (Some(atlas_rect), Some(mut image_rect)) => {
                image_rect.min += atlas_rect.min;
                image_rect.max += atlas_rect.min;
                Some(image_rect)
            }
        };

        extracted_ui_slicers
            .slices
            .entry(main_entity)
            .or_insert_with(|| (extracted_camera_entity, Default::default()))
            .1
            .insert(
                commands.spawn_empty().id(),
                ExtractedUiTextureSlice {
                    stack_index: stack_index.0,
                    transform: Affine2::from(*transform)
                        * Affine2::from_translation(visual_box.center()),
                    color: image.color.into(),
                    rect: Rect {
                        min: Vec2::ZERO,
                        max: visual_box.size(),
                    },
                    clip: clip.cloned(),
                    image: image.image.id(),
                    image_scale_mode,
                    atlas_rect,
                    flip_x: image.flip_x,
                    flip_y: image.flip_y,
                    inverse_scale_factor: uinode.inverse_scale_factor,
                },
            );
    }

    // Only remove the render-world data if we didn't handle the node above.
    // It's possible that a relevant component was removed and added in the same
    // frame.
    for main_entity in removed_computed_node_query
        .read()
        .chain(removed_computed_stack_index_query.read())
        .chain(removed_ui_global_transform_query.read())
        .chain(removed_inherited_visibility_query.read())
        .chain(removed_computed_ui_target_camera_query.read())
        .chain(removed_image_node_query.read())
    {
        let main_entity = MainEntity::from(main_entity);
        if nodes_processed_this_frame.contains(&main_entity) {
            continue;
        }
        let Some((_, mut extracted_nodes)) = extracted_ui_slicers.slices.remove(&main_entity)
        else {
            continue;
        };
        for (render_entity, _) in extracted_nodes.drain(..) {
            commands.entity(render_entity).despawn();
        }
    }
}

#[expect(
    clippy::too_many_arguments,
    reason = "it's a system that needs a lot of them"
)]
pub fn queue_ui_slices(
    extracted_ui_slicers: ResMut<ExtractedUiTextureSlices>,
    ui_slicer_pipeline: Res<UiTextureSlicePipeline>,
    mut pipelines: ResMut<SpecializedRenderPipelines<UiTextureSlicePipeline>>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<TransparentUi>>,
    render_views: Query<&UiCameraView, With<ExtractedView>>,
    camera_views: Query<&ExtractedView>,
    pipeline_cache: Res<PipelineCache>,
    draw_functions: Res<DrawFunctions<TransparentUi>>,
) {
    let draw_function = draw_functions.read().id::<DrawUiTextureSlices>();
    let mut current_camera_entity = Entity::PLACEHOLDER;
    let mut current_phase = None;

    for (main_entity, (extracted_camera_entity, subslices)) in extracted_ui_slicers.slices.iter() {
        if current_camera_entity != *extracted_camera_entity {
            current_phase =
                render_views
                    .get(*extracted_camera_entity)
                    .ok()
                    .and_then(|default_camera_view| {
                        camera_views
                            .get(default_camera_view.0)
                            .ok()
                            .and_then(|view| {
                                transparent_render_phases
                                    .get_mut(&view.retained_view_entity)
                                    .map(|transparent_phase| {
                                        let pipeline = pipelines.specialize(
                                            &pipeline_cache,
                                            &ui_slicer_pipeline,
                                            UiTextureSlicePipelineKey {
                                                target_format: view.target_format,
                                            },
                                        );
                                        (pipeline, transparent_phase)
                                    })
                            })
                    });
            current_camera_entity = *extracted_camera_entity;
        }

        let Some((pipeline, transparent_phase)) = current_phase.as_mut() else {
            continue;
        };
        for (render_entity, extracted_slicer) in subslices.iter() {
            transparent_phase.add_transient(TransparentUi {
                draw_function,
                pipeline: *pipeline,
                entity: (*render_entity, *main_entity),
                sort_key: FloatOrd(extracted_slicer.stack_index as f32 + stack_z_offsets::IMAGE),
                batch_range: 0..0,
                extra_index: PhaseItemExtraIndex::None,
                indexed: true,
            });
        }
    }
}

pub fn prepare_ui_slices(
    mut commands: Commands,
    render_device: Res<RenderDevice>,
    render_queue: Res<RenderQueue>,
    pipeline_cache: Res<PipelineCache>,
    mut ui_meta: ResMut<UiTextureSliceMeta>,
    extracted_slices: Res<ExtractedUiTextureSlices>,
    view_uniforms: Res<ViewUniforms>,
    texture_slicer_pipeline: Res<UiTextureSlicePipeline>,
    mut image_bind_groups: ResMut<UiTextureSliceImageBindGroups>,
    gpu_images: Res<RenderAssets<GpuImage>>,
    mut phases: ResMut<ViewSortedRenderPhases<TransparentUi>>,
    events: Res<SpriteAssetEvents>,
    mut previous_len: Local<usize>,
) {
    // If an image has changed, the GpuImage has (probably) changed
    for event in &events.images {
        match event {
            AssetEvent::Added { .. } |
            AssetEvent::Unused { .. } |
            // Images don't have dependencies
            AssetEvent::LoadedWithDependencies { .. } => {}
            AssetEvent::Modified { id } | AssetEvent::Removed { id } => {
                image_bind_groups.values.remove(id);
            }
        };
    }

    if let Some(view_binding) = view_uniforms.uniforms.binding() {
        let mut batches: Vec<(Entity, UiTextureSlicerBatch)> = Vec::with_capacity(*previous_len);

        ui_meta.vertices.clear();
        ui_meta.indices.clear();
        ui_meta.view_bind_group = Some(render_device.create_bind_group(
            "ui_texture_slice_view_bind_group",
            &pipeline_cache.get_bind_group_layout(&texture_slicer_pipeline.view_layout),
            &BindGroupEntries::single(view_binding),
        ));

        // Buffer indexes
        let mut vertices_index = 0;
        let mut indices_index = 0;

        for ui_phase in phases.values_mut() {
            let mut batch_item_index = 0;
            let mut batch_image_handle = None;
            let mut batch_image_size = Vec2::ZERO;

            for item_index in 0..ui_phase.items.len() {
                let item = &mut ui_phase.items[item_index];
                if let Some(texture_slices) = extracted_slices
                    .slices
                    .get(&item.main_entity())
                    .and_then(|(_, subslices)| subslices.get(&item.entity()))
                {
                    // Initialize the batch range to be zero-length initially.
                    // We'll extend it as we accumulate items into this batch.
                    item.batch_range = (item_index as u32)..(item_index as u32);

                    let mut existing_batch = batches.last_mut();

                    if batch_image_handle.is_none()
                        || existing_batch.is_none()
                        || (batch_image_handle != Some(AssetId::default())
                            && texture_slices.image != AssetId::default()
                            && batch_image_handle != Some(texture_slices.image))
                    {
                        if let Some(gpu_image) = gpu_images.get(texture_slices.image) {
                            batch_item_index = item_index;
                            batch_image_handle = Some(texture_slices.image);
                            batch_image_size = gpu_image.size_2d().as_vec2();

                            let new_batch = UiTextureSlicerBatch {
                                range: vertices_index..vertices_index,
                                image: texture_slices.image,
                            };

                            batches.push((item.entity(), new_batch));

                            image_bind_groups
                                .values
                                .entry(texture_slices.image)
                                .or_insert_with(|| {
                                    render_device.create_bind_group(
                                        "ui_texture_slice_image_layout",
                                        &pipeline_cache.get_bind_group_layout(
                                            &texture_slicer_pipeline.image_layout,
                                        ),
                                        &BindGroupEntries::sequential((
                                            &gpu_image.texture_view,
                                            &gpu_image.sampler,
                                        )),
                                    )
                                });

                            existing_batch = batches.last_mut();
                        } else {
                            continue;
                        }
                    } else if let Some(ref mut existing_batch) = existing_batch
                        && batch_image_handle == Some(AssetId::default())
                        && texture_slices.image != AssetId::default()
                    {
                        if let Some(gpu_image) = gpu_images.get(texture_slices.image) {
                            batch_image_handle = Some(texture_slices.image);
                            batch_image_size = gpu_image.size_2d().as_vec2();
                            existing_batch.1.image = texture_slices.image;

                            image_bind_groups
                                .values
                                .entry(texture_slices.image)
                                .or_insert_with(|| {
                                    render_device.create_bind_group(
                                        "ui_texture_slice_image_layout",
                                        &pipeline_cache.get_bind_group_layout(
                                            &texture_slicer_pipeline.image_layout,
                                        ),
                                        &BindGroupEntries::sequential((
                                            &gpu_image.texture_view,
                                            &gpu_image.sampler,
                                        )),
                                    )
                                });
                        } else {
                            continue;
                        }
                    }

                    let uinode_rect = texture_slices.rect;

                    let rect_size = uinode_rect.size();

                    // Specify the corners of the node
                    let positions = QUAD_VERTEX_POSITIONS
                        .map(|pos| texture_slices.transform.transform_point2(pos * rect_size));

                    let uvs = [Vec2::ZERO, Vec2::X, Vec2::ONE, Vec2::Y];

                    let color = texture_slices.color.to_f32_array();

                    let (image_size, mut atlas) = if let Some(atlas) = texture_slices.atlas_rect {
                        (
                            atlas.size(),
                            [
                                atlas.min.x / batch_image_size.x,
                                atlas.min.y / batch_image_size.y,
                                atlas.max.x / batch_image_size.x,
                                atlas.max.y / batch_image_size.y,
                            ],
                        )
                    } else {
                        (batch_image_size, [0., 0., 1., 1.])
                    };

                    if texture_slices.flip_x {
                        atlas.swap(0, 2);
                    }

                    if texture_slices.flip_y {
                        atlas.swap(1, 3);
                    }

                    let [slices, border, repeat] = compute_texture_slices(
                        image_size,
                        uinode_rect.size() * texture_slices.inverse_scale_factor,
                        &texture_slices.image_scale_mode,
                    );

                    let vertices = clip_polygon(
                        texture_slices.clip.as_ref(),
                        &[
                            (positions[0], uvs[0]),
                            (positions[1], uvs[1]),
                            (positions[2], uvs[2]),
                            (positions[3], uvs[3]),
                        ],
                        Vec2::lerp,
                    );
                    if vertices.is_empty() {
                        continue;
                    }

                    for vertex in &vertices {
                        ui_meta.vertices.push(UiTextureSliceVertex {
                            position: vertex.0.extend(0.).into(),
                            uv: vertex.1.into(),
                            color,
                            slices,
                            border,
                            repeat,
                            atlas,
                        });
                    }

                    for i in 1..vertices.len() as u32 - 1 {
                        ui_meta.indices.push(indices_index);
                        ui_meta.indices.push(indices_index + i);
                        ui_meta.indices.push(indices_index + i + 1);
                    }

                    vertices_index += 3 * (vertices.len() as u32 - 2);
                    indices_index += vertices.len() as u32;

                    existing_batch.unwrap().1.range.end = vertices_index;
                    ui_phase.items[batch_item_index].batch_range_mut().end += 1;
                } else {
                    batch_image_handle = None;
                }
            }
        }
        ui_meta.vertices.write_buffer(&render_device, &render_queue);
        ui_meta.indices.write_buffer(&render_device, &render_queue);
        *previous_len = batches.len();
        commands.try_insert_batch(batches);
    }
}

pub type DrawUiTextureSlices = (
    SetItemPipeline,
    SetSlicerViewBindGroup<0>,
    SetSlicerTextureBindGroup<1>,
    DrawSlicer,
);

pub struct SetSlicerViewBindGroup<const I: usize>;
impl<P: PhaseItem, const I: usize> RenderCommand<P> for SetSlicerViewBindGroup<I> {
    type Param = SRes<UiTextureSliceMeta>;
    type ViewQuery = Read<ViewUniformOffset>;
    type ItemQuery = ();

    fn render<'w>(
        _item: &P,
        view_uniform: &'w ViewUniformOffset,
        _entity: Option<()>,
        ui_meta: SystemParamItem<'w, '_, Self::Param>,
        pass: &mut TrackedRenderPass<'w>,
    ) -> RenderCommandResult {
        let Some(view_bind_group) = ui_meta.into_inner().view_bind_group.as_ref() else {
            return RenderCommandResult::Failure("view_bind_group not available");
        };
        pass.set_bind_group(I, view_bind_group, &[view_uniform.offset]);
        RenderCommandResult::Success
    }
}
pub struct SetSlicerTextureBindGroup<const I: usize>;
impl<P: PhaseItem, const I: usize> RenderCommand<P> for SetSlicerTextureBindGroup<I> {
    type Param = SRes<UiTextureSliceImageBindGroups>;
    type ViewQuery = ();
    type ItemQuery = Read<UiTextureSlicerBatch>;

    #[inline]
    fn render<'w>(
        _item: &P,
        _view: (),
        batch: Option<&'w UiTextureSlicerBatch>,
        image_bind_groups: SystemParamItem<'w, '_, Self::Param>,
        pass: &mut TrackedRenderPass<'w>,
    ) -> RenderCommandResult {
        let image_bind_groups = image_bind_groups.into_inner();
        let Some(batch) = batch else {
            return RenderCommandResult::Skip;
        };

        pass.set_bind_group(I, image_bind_groups.values.get(&batch.image).unwrap(), &[]);
        RenderCommandResult::Success
    }
}
pub struct DrawSlicer;
impl<P: PhaseItem> RenderCommand<P> for DrawSlicer {
    type Param = SRes<UiTextureSliceMeta>;
    type ViewQuery = ();
    type ItemQuery = Read<UiTextureSlicerBatch>;

    #[inline]
    fn render<'w>(
        _item: &P,
        _view: (),
        batch: Option<&'w UiTextureSlicerBatch>,
        ui_meta: SystemParamItem<'w, '_, Self::Param>,
        pass: &mut TrackedRenderPass<'w>,
    ) -> RenderCommandResult {
        let Some(batch) = batch else {
            return RenderCommandResult::Skip;
        };
        let ui_meta = ui_meta.into_inner();
        let Some(vertices) = ui_meta.vertices.buffer() else {
            return RenderCommandResult::Failure("missing vertices to draw ui");
        };
        let Some(indices) = ui_meta.indices.buffer() else {
            return RenderCommandResult::Failure("missing indices to draw ui");
        };

        // Store the vertices
        pass.set_vertex_buffer(0, vertices.slice(..));
        // Define how to "connect" the vertices
        pass.set_index_buffer(indices.slice(..), IndexFormat::Uint32);
        // Draw the vertices
        pass.draw_indexed(batch.range.clone(), 0, 0..1);
        RenderCommandResult::Success
    }
}

fn compute_texture_slices(
    image_size: Vec2,
    target_size: Vec2,
    image_scale_mode: &SpriteImageMode,
) -> [[f32; 4]; 3] {
    match image_scale_mode {
        SpriteImageMode::Sliced(TextureSlicer {
            border: border_rect,
            center_scale_mode,
            sides_scale_mode,
            max_corner_scale,
        }) => {
            let min_coeff = (target_size / image_size)
                .min_element()
                .min(*max_corner_scale);

            // calculate the normalized extents of the nine-patched image slices
            let slices = [
                border_rect.min_inset.x / image_size.x,
                border_rect.min_inset.y / image_size.y,
                1. - border_rect.max_inset.x / image_size.x,
                1. - border_rect.max_inset.y / image_size.y,
            ];

            // calculate the normalized extents of the target slices
            let border = [
                (border_rect.min_inset.x / target_size.x) * min_coeff,
                (border_rect.min_inset.y / target_size.y) * min_coeff,
                1. - (border_rect.max_inset.x / target_size.x) * min_coeff,
                1. - (border_rect.max_inset.y / target_size.y) * min_coeff,
            ];

            let image_side_width = image_size.x * (slices[2] - slices[0]);
            let image_side_height = image_size.y * (slices[3] - slices[1]);
            let target_side_width = target_size.x * (border[2] - border[0]);
            let target_side_height = target_size.y * (border[3] - border[1]);

            // compute the number of times to repeat the side and center slices when tiling along each axis
            // if the returned value is `1.` the slice will be stretched to fill the axis.
            let repeat_side_x =
                compute_tiled_subaxis(image_side_width, target_side_width, sides_scale_mode);
            let repeat_side_y =
                compute_tiled_subaxis(image_side_height, target_side_height, sides_scale_mode);
            let repeat_center_x =
                compute_tiled_subaxis(image_side_width, target_side_width, center_scale_mode);
            let repeat_center_y =
                compute_tiled_subaxis(image_side_height, target_side_height, center_scale_mode);

            [
                slices,
                border,
                [
                    repeat_side_x,
                    repeat_side_y,
                    repeat_center_x,
                    repeat_center_y,
                ],
            ]
        }
        SpriteImageMode::Tiled {
            tile_x,
            tile_y,
            stretch_value,
        } => {
            let rx = compute_tiled_axis(*tile_x, image_size.x, target_size.x, *stretch_value);
            let ry = compute_tiled_axis(*tile_y, image_size.y, target_size.y, *stretch_value);
            [[0., 0., 1., 1.], [0., 0., 1., 1.], [1., 1., rx, ry]]
        }
        SpriteImageMode::Auto => {
            unreachable!("Slices can not be computed for SpriteImageMode::Stretch")
        }
        SpriteImageMode::Scale(_) => {
            unreachable!("Slices can not be computed for SpriteImageMode::Scale")
        }
    }
}

fn compute_tiled_axis(tile: bool, image_extent: f32, target_extent: f32, stretch: f32) -> f32 {
    if tile {
        let s = image_extent * stretch;
        target_extent / s
    } else {
        1.
    }
}

fn compute_tiled_subaxis(image_extent: f32, target_extent: f32, mode: &SliceScaleMode) -> f32 {
    match mode {
        SliceScaleMode::Stretch => 1.,
        SliceScaleMode::Tile { stretch_value } => {
            let s = image_extent * *stretch_value;
            target_extent / s
        }
    }
}