bevy/crates/bevy_ui/src/render/ui_material_pipeline.rs

use std::{hash::Hash, marker::PhantomData, ops::Range};

use bevy_asset::*;
use bevy_ecs::{
    prelude::Component,
    query::ROQueryItem,
    storage::SparseSet,
    system::lifetimeless::{Read, SRes},
    system::*,
};
use bevy_math::{FloatOrd, Mat4, Rect, Vec2, Vec4Swizzles};
use bevy_render::{
    extract_component::ExtractComponentPlugin,
    globals::{GlobalsBuffer, GlobalsUniform},
    render_asset::{PrepareAssetError, RenderAsset, RenderAssetPlugin, RenderAssets},
    render_phase::*,
    render_resource::{binding_types::uniform_buffer, *},
    renderer::{RenderDevice, RenderQueue},
    texture::{BevyDefault, FallbackImage, GpuImage},
    view::*,
    Extract, ExtractSchedule, Render, RenderSet,
};
use bevy_transform::prelude::GlobalTransform;
use bevy_window::{PrimaryWindow, Window};
use bytemuck::{Pod, Zeroable};

use crate::*;

pub const UI_MATERIAL_SHADER_HANDLE: Handle<Shader> = Handle::weak_from_u128(10074188772096983955);

const UI_VERTEX_OUTPUT_SHADER_HANDLE: Handle<Shader> = Handle::weak_from_u128(10123618247720234751);

/// Adds the necessary ECS resources and render logic to enable rendering entities using the given
/// [`UiMaterial`] asset type (which includes [`UiMaterial`] types).
pub struct UiMaterialPlugin<M: UiMaterial>(PhantomData<M>);

impl<M: UiMaterial> Default for UiMaterialPlugin<M> {
    fn default() -> Self {
        Self(Default::default())
    }
}

impl<M: UiMaterial> Plugin for UiMaterialPlugin<M>
where
    M::Data: PartialEq + Eq + Hash + Clone,
{
    fn build(&self, app: &mut App) {
        load_internal_asset!(
            app,
            UI_VERTEX_OUTPUT_SHADER_HANDLE,
            "ui_vertex_output.wgsl",
            Shader::from_wgsl
        );
        load_internal_asset!(
            app,
            UI_MATERIAL_SHADER_HANDLE,
            "ui_material.wgsl",
            Shader::from_wgsl
        );
        app.init_asset::<M>().add_plugins((
            ExtractComponentPlugin::<Handle<M>>::extract_visible(),
            RenderAssetPlugin::<PreparedUiMaterial<M>>::default(),
        ));

        if let Some(render_app) = app.get_sub_app_mut(RenderApp) {
            render_app
                .add_render_command::<TransparentUi, DrawUiMaterial<M>>()
                .init_resource::<ExtractedUiMaterialNodes<M>>()
                .init_resource::<UiMaterialMeta<M>>()
                .init_resource::<SpecializedRenderPipelines<UiMaterialPipeline<M>>>()
                .add_systems(
                    ExtractSchedule,
                    extract_ui_material_nodes::<M>.in_set(RenderUiSystem::ExtractBackgrounds),
                )
                .add_systems(
                    Render,
                    (
                        queue_ui_material_nodes::<M>.in_set(RenderSet::Queue),
                        prepare_uimaterial_nodes::<M>.in_set(RenderSet::PrepareBindGroups),
                    ),
                );
        }
    }

    fn finish(&self, app: &mut App) {
        if let Some(render_app) = app.get_sub_app_mut(RenderApp) {
            render_app.init_resource::<UiMaterialPipeline<M>>();
        }
    }
}

#[derive(Resource)]
pub struct UiMaterialMeta<M: UiMaterial> {
    vertices: BufferVec<UiMaterialVertex>,
    view_bind_group: Option<BindGroup>,
    marker: PhantomData<M>,
}

impl<M: UiMaterial> Default for UiMaterialMeta<M> {
    fn default() -> Self {
        Self {
            vertices: BufferVec::new(BufferUsages::VERTEX),
            view_bind_group: Default::default(),
            marker: PhantomData,
        }
    }
}

#[repr(C)]
#[derive(Copy, Clone, Pod, Zeroable)]
pub struct UiMaterialVertex {
    pub position: [f32; 3],
    pub uv: [f32; 2],
    pub size: [f32; 2],
    pub border_widths: [f32; 4],
}

// in this [`UiMaterialPipeline`] there is (currently) no batching going on.
// Therefore the [`UiMaterialBatch`] is more akin to a draw call.
#[derive(Component)]
pub struct UiMaterialBatch<M: UiMaterial> {
    /// The range of vertices inside the [`UiMaterialMeta`]
    pub range: Range<u32>,
    pub material: AssetId<M>,
}

/// Render pipeline data for a given [`UiMaterial`]
#[derive(Resource)]
pub struct UiMaterialPipeline<M: UiMaterial> {
    pub ui_layout: BindGroupLayout,
    pub view_layout: BindGroupLayout,
    pub vertex_shader: Option<Handle<Shader>>,
    pub fragment_shader: Option<Handle<Shader>>,
    marker: PhantomData<M>,
}

impl<M: UiMaterial> SpecializedRenderPipeline for UiMaterialPipeline<M>
where
    M::Data: PartialEq + Eq + Hash + Clone,
{
    type Key = UiMaterialKey<M>;

    fn specialize(&self, key: Self::Key) -> RenderPipelineDescriptor {
        let vertex_layout = VertexBufferLayout::from_vertex_formats(
            VertexStepMode::Vertex,
            vec![
                // position
                VertexFormat::Float32x3,
                // uv
                VertexFormat::Float32x2,
                // size
                VertexFormat::Float32x2,
                // border_widths
                VertexFormat::Float32x4,
            ],
        );
        let shader_defs = Vec::new();

        let mut descriptor = RenderPipelineDescriptor {
            vertex: VertexState {
                shader: UI_MATERIAL_SHADER_HANDLE,
                entry_point: "vertex".into(),
                shader_defs: shader_defs.clone(),
                buffers: vec![vertex_layout],
            },
            fragment: Some(FragmentState {
                shader: UI_MATERIAL_SHADER_HANDLE,
                shader_defs,
                entry_point: "fragment".into(),
                targets: vec![Some(ColorTargetState {
                    format: if key.hdr {
                        ViewTarget::TEXTURE_FORMAT_HDR
                    } else {
                        TextureFormat::bevy_default()
                    },
                    blend: Some(BlendState::ALPHA_BLENDING),
                    write_mask: ColorWrites::ALL,
                })],
            }),
            layout: vec![],
            push_constant_ranges: Vec::new(),
            primitive: PrimitiveState {
                front_face: FrontFace::Ccw,
                cull_mode: None,
                unclipped_depth: false,
                polygon_mode: PolygonMode::Fill,
                conservative: false,
                topology: PrimitiveTopology::TriangleList,
                strip_index_format: None,
            },
            depth_stencil: None,
            multisample: MultisampleState {
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            label: Some("ui_material_pipeline".into()),
        };
        if let Some(vertex_shader) = &self.vertex_shader {
            descriptor.vertex.shader = vertex_shader.clone();
        }

        if let Some(fragment_shader) = &self.fragment_shader {
            descriptor.fragment.as_mut().unwrap().shader = fragment_shader.clone();
        }

        descriptor.layout = vec![self.view_layout.clone(), self.ui_layout.clone()];

        M::specialize(&mut descriptor, key);

        descriptor
    }
}

impl<M: UiMaterial> FromWorld for UiMaterialPipeline<M> {
    fn from_world(world: &mut World) -> Self {
        let asset_server = world.resource::<AssetServer>();
        let render_device = world.resource::<RenderDevice>();
        let ui_layout = M::bind_group_layout(render_device);

        let view_layout = render_device.create_bind_group_layout(
            "ui_view_layout",
            &BindGroupLayoutEntries::sequential(
                ShaderStages::VERTEX_FRAGMENT,
                (
                    uniform_buffer::<ViewUniform>(true),
                    uniform_buffer::<GlobalsUniform>(false),
                ),
            ),
        );

        UiMaterialPipeline {
            ui_layout,
            view_layout,
            vertex_shader: match M::vertex_shader() {
                ShaderRef::Default => None,
                ShaderRef::Handle(handle) => Some(handle),
                ShaderRef::Path(path) => Some(asset_server.load(path)),
            },
            fragment_shader: match M::fragment_shader() {
                ShaderRef::Default => None,
                ShaderRef::Handle(handle) => Some(handle),
                ShaderRef::Path(path) => Some(asset_server.load(path)),
            },
            marker: PhantomData,
        }
    }
}

pub type DrawUiMaterial<M> = (
    SetItemPipeline,
    SetMatUiViewBindGroup<M, 0>,
    SetUiMaterialBindGroup<M, 1>,
    DrawUiMaterialNode<M>,
);

pub struct SetMatUiViewBindGroup<M: UiMaterial, const I: usize>(PhantomData<M>);
impl<P: PhaseItem, M: UiMaterial, const I: usize> RenderCommand<P> for SetMatUiViewBindGroup<M, I> {
    type Param = SRes<UiMaterialMeta<M>>;
    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 {
        pass.set_bind_group(
            I,
            ui_meta.into_inner().view_bind_group.as_ref().unwrap(),
            &[view_uniform.offset],
        );
        RenderCommandResult::Success
    }
}

pub struct SetUiMaterialBindGroup<M: UiMaterial, const I: usize>(PhantomData<M>);
impl<P: PhaseItem, M: UiMaterial, const I: usize> RenderCommand<P>
    for SetUiMaterialBindGroup<M, I>
{
    type Param = SRes<RenderAssets<PreparedUiMaterial<M>>>;
    type ViewQuery = ();
    type ItemQuery = Read<UiMaterialBatch<M>>;

    fn render<'w>(
        _item: &P,
        _view: (),
        material_handle: Option<ROQueryItem<'_, Self::ItemQuery>>,
        materials: SystemParamItem<'w, '_, Self::Param>,
        pass: &mut TrackedRenderPass<'w>,
    ) -> RenderCommandResult {
        let Some(material_handle) = material_handle else {
            return RenderCommandResult::Failure;
        };
        let Some(material) = materials.into_inner().get(material_handle.material) else {
            return RenderCommandResult::Failure;
        };
        pass.set_bind_group(I, &material.bind_group, &[]);
        RenderCommandResult::Success
    }
}

pub struct DrawUiMaterialNode<M>(PhantomData<M>);
impl<P: PhaseItem, M: UiMaterial> RenderCommand<P> for DrawUiMaterialNode<M> {
    type Param = SRes<UiMaterialMeta<M>>;
    type ViewQuery = ();
    type ItemQuery = Read<UiMaterialBatch<M>>;

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

        pass.set_vertex_buffer(0, ui_meta.into_inner().vertices.buffer().unwrap().slice(..));
        pass.draw(batch.range.clone(), 0..1);
        RenderCommandResult::Success
    }
}

pub struct ExtractedUiMaterialNode<M: UiMaterial> {
    pub stack_index: usize,
    pub transform: Mat4,
    pub rect: Rect,
    pub border: [f32; 4],
    pub material: AssetId<M>,
    pub clip: Option<Rect>,
    // Camera to render this UI node to. By the time it is extracted,
    // it is defaulted to a single camera if only one exists.
    // Nodes with ambiguous camera will be ignored.
    pub camera_entity: Entity,
}

#[derive(Resource)]
pub struct ExtractedUiMaterialNodes<M: UiMaterial> {
    pub uinodes: SparseSet<Entity, ExtractedUiMaterialNode<M>>,
}

impl<M: UiMaterial> Default for ExtractedUiMaterialNodes<M> {
    fn default() -> Self {
        Self {
            uinodes: Default::default(),
        }
    }
}

pub fn extract_ui_material_nodes<M: UiMaterial>(
    mut extracted_uinodes: ResMut<ExtractedUiMaterialNodes<M>>,
    materials: Extract<Res<Assets<M>>>,
    ui_stack: Extract<Res<UiStack>>,
    default_ui_camera: Extract<DefaultUiCamera>,
    uinode_query: Extract<
        Query<
            (
                Entity,
                &Node,
                &Style,
                &GlobalTransform,
                &Handle<M>,
                &ViewVisibility,
                Option<&CalculatedClip>,
                Option<&TargetCamera>,
            ),
            Without<BackgroundColor>,
        >,
    >,
    windows: Extract<Query<&Window, With<PrimaryWindow>>>,
    ui_scale: Extract<Res<UiScale>>,
) {
    let ui_logical_viewport_size = windows
        .get_single()
        .map(|window| window.size())
        .unwrap_or(Vec2::ZERO)
        // The logical window resolution returned by `Window` only takes into account the window scale factor and not `UiScale`,
        // so we have to divide by `UiScale` to get the size of the UI viewport.
        / ui_scale.0;

    // If there is only one camera, we use it as default
    let default_single_camera = default_ui_camera.get();

    for (stack_index, entity) in ui_stack.uinodes.iter().enumerate() {
        if let Ok((entity, uinode, style, transform, handle, view_visibility, clip, camera)) =
            uinode_query.get(*entity)
        {
            let Some(camera_entity) = camera.map(TargetCamera::entity).or(default_single_camera)
            else {
                continue;
            };

            // skip invisible nodes
            if !view_visibility.get() {
                continue;
            }

            // Skip loading materials
            if !materials.contains(handle) {
                continue;
            }

            // Both vertical and horizontal percentage border values are calculated based on the width of the parent node
            // <https://developer.mozilla.org/en-US/docs/Web/CSS/border-width>
            let parent_width = uinode.size().x;
            let left =
                resolve_border_thickness(style.border.left, parent_width, ui_logical_viewport_size)
                    / uinode.size().x;
            let right = resolve_border_thickness(
                style.border.right,
                parent_width,
                ui_logical_viewport_size,
            ) / uinode.size().x;
            let top =
                resolve_border_thickness(style.border.top, parent_width, ui_logical_viewport_size)
                    / uinode.size().y;
            let bottom = resolve_border_thickness(
                style.border.bottom,
                parent_width,
                ui_logical_viewport_size,
            ) / uinode.size().y;

            extracted_uinodes.uinodes.insert(
                entity,
                ExtractedUiMaterialNode {
                    stack_index,
                    transform: transform.compute_matrix(),
                    material: handle.id(),
                    rect: Rect {
                        min: Vec2::ZERO,
                        max: uinode.calculated_size,
                    },
                    border: [left, right, top, bottom],
                    clip: clip.map(|clip| clip.clip),
                    camera_entity,
                },
            );
        };
    }
}

#[allow(clippy::too_many_arguments)]
pub fn prepare_uimaterial_nodes<M: UiMaterial>(
    mut commands: Commands,
    render_device: Res<RenderDevice>,
    render_queue: Res<RenderQueue>,
    mut ui_meta: ResMut<UiMaterialMeta<M>>,
    mut extracted_uinodes: ResMut<ExtractedUiMaterialNodes<M>>,
    view_uniforms: Res<ViewUniforms>,
    globals_buffer: Res<GlobalsBuffer>,
    ui_material_pipeline: Res<UiMaterialPipeline<M>>,
    mut phases: Query<&mut SortedRenderPhase<TransparentUi>>,
    mut previous_len: Local<usize>,
) {
    if let (Some(view_binding), Some(globals_binding)) = (
        view_uniforms.uniforms.binding(),
        globals_buffer.buffer.binding(),
    ) {
        let mut batches: Vec<(Entity, UiMaterialBatch<M>)> = Vec::with_capacity(*previous_len);

        ui_meta.vertices.clear();
        ui_meta.view_bind_group = Some(render_device.create_bind_group(
            "ui_material_view_bind_group",
            &ui_material_pipeline.view_layout,
            &BindGroupEntries::sequential((view_binding, globals_binding)),
        ));
        let mut index = 0;

        for mut ui_phase in &mut phases {
            let mut batch_item_index = 0;
            let mut batch_shader_handle = AssetId::invalid();

            for item_index in 0..ui_phase.items.len() {
                let item = &mut ui_phase.items[item_index];
                if let Some(extracted_uinode) = extracted_uinodes.uinodes.get(item.entity) {
                    let mut existing_batch = batches
                        .last_mut()
                        .filter(|_| batch_shader_handle == extracted_uinode.material);

                    if existing_batch.is_none() {
                        batch_item_index = item_index;
                        batch_shader_handle = extracted_uinode.material;

                        let new_batch = UiMaterialBatch {
                            range: index..index,
                            material: extracted_uinode.material,
                        };

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

                        existing_batch = batches.last_mut();
                    }

                    let uinode_rect = extracted_uinode.rect;

                    let rect_size = uinode_rect.size().extend(1.0);

                    let positions = QUAD_VERTEX_POSITIONS.map(|pos| {
                        (extracted_uinode.transform * (pos * rect_size).extend(1.0)).xyz()
                    });

                    let positions_diff = if let Some(clip) = extracted_uinode.clip {
                        [
                            Vec2::new(
                                f32::max(clip.min.x - positions[0].x, 0.),
                                f32::max(clip.min.y - positions[0].y, 0.),
                            ),
                            Vec2::new(
                                f32::min(clip.max.x - positions[1].x, 0.),
                                f32::max(clip.min.y - positions[1].y, 0.),
                            ),
                            Vec2::new(
                                f32::min(clip.max.x - positions[2].x, 0.),
                                f32::min(clip.max.y - positions[2].y, 0.),
                            ),
                            Vec2::new(
                                f32::max(clip.min.x - positions[3].x, 0.),
                                f32::min(clip.max.y - positions[3].y, 0.),
                            ),
                        ]
                    } else {
                        [Vec2::ZERO; 4]
                    };

                    let positions_clipped = [
                        positions[0] + positions_diff[0].extend(0.),
                        positions[1] + positions_diff[1].extend(0.),
                        positions[2] + positions_diff[2].extend(0.),
                        positions[3] + positions_diff[3].extend(0.),
                    ];

                    let transformed_rect_size =
                        extracted_uinode.transform.transform_vector3(rect_size);

                    // Don't try to cull nodes that have a rotation
                    // In a rotation around the Z-axis, this value is 0.0 for an angle of 0.0 or π
                    // In those two cases, the culling check can proceed normally as corners will be on
                    // horizontal / vertical lines
                    // For all other angles, bypass the culling check
                    // This does not properly handles all rotations on all axis
                    if extracted_uinode.transform.x_axis[1] == 0.0 {
                        // Cull nodes that are completely clipped
                        if positions_diff[0].x - positions_diff[1].x >= transformed_rect_size.x
                            || positions_diff[1].y - positions_diff[2].y >= transformed_rect_size.y
                        {
                            continue;
                        }
                    }
                    let uvs = [
                        Vec2::new(
                            uinode_rect.min.x + positions_diff[0].x,
                            uinode_rect.min.y + positions_diff[0].y,
                        ),
                        Vec2::new(
                            uinode_rect.max.x + positions_diff[1].x,
                            uinode_rect.min.y + positions_diff[1].y,
                        ),
                        Vec2::new(
                            uinode_rect.max.x + positions_diff[2].x,
                            uinode_rect.max.y + positions_diff[2].y,
                        ),
                        Vec2::new(
                            uinode_rect.min.x + positions_diff[3].x,
                            uinode_rect.max.y + positions_diff[3].y,
                        ),
                    ]
                    .map(|pos| pos / uinode_rect.max);

                    for i in QUAD_INDICES {
                        ui_meta.vertices.push(UiMaterialVertex {
                            position: positions_clipped[i].into(),
                            uv: uvs[i].into(),
                            size: extracted_uinode.rect.size().into(),
                            border_widths: extracted_uinode.border,
                        });
                    }

                    index += QUAD_INDICES.len() as u32;
                    existing_batch.unwrap().1.range.end = index;
                    ui_phase.items[batch_item_index].batch_range_mut().end += 1;
                } else {
                    batch_shader_handle = AssetId::invalid();
                }
            }
        }
        ui_meta.vertices.write_buffer(&render_device, &render_queue);
        *previous_len = batches.len();
        commands.insert_or_spawn_batch(batches);
    }
    extracted_uinodes.uinodes.clear();
}

pub struct PreparedUiMaterial<T: UiMaterial> {
    pub bindings: Vec<(u32, OwnedBindingResource)>,
    pub bind_group: BindGroup,
    pub key: T::Data,
}

impl<M: UiMaterial> RenderAsset for PreparedUiMaterial<M> {
    type SourceAsset = M;

    type Param = (
        SRes<RenderDevice>,
        SRes<RenderAssets<GpuImage>>,
        SRes<FallbackImage>,
        SRes<UiMaterialPipeline<M>>,
    );

    fn prepare_asset(
        material: Self::SourceAsset,
        (render_device, images, fallback_image, pipeline): &mut SystemParamItem<Self::Param>,
    ) -> Result<Self, PrepareAssetError<Self::SourceAsset>> {
        match material.as_bind_group(&pipeline.ui_layout, render_device, images, fallback_image) {
            Ok(prepared) => Ok(PreparedUiMaterial {
                bindings: prepared.bindings,
                bind_group: prepared.bind_group,
                key: prepared.data,
            }),
            Err(AsBindGroupError::RetryNextUpdate) => {
                Err(PrepareAssetError::RetryNextUpdate(material))
            }
        }
    }
}

#[allow(clippy::too_many_arguments)]
pub fn queue_ui_material_nodes<M: UiMaterial>(
    extracted_uinodes: Res<ExtractedUiMaterialNodes<M>>,
    draw_functions: Res<DrawFunctions<TransparentUi>>,
    ui_material_pipeline: Res<UiMaterialPipeline<M>>,
    mut pipelines: ResMut<SpecializedRenderPipelines<UiMaterialPipeline<M>>>,
    pipeline_cache: Res<PipelineCache>,
    render_materials: Res<RenderAssets<PreparedUiMaterial<M>>>,
    mut views: Query<(&ExtractedView, &mut SortedRenderPhase<TransparentUi>)>,
) where
    M::Data: PartialEq + Eq + Hash + Clone,
{
    let draw_function = draw_functions.read().id::<DrawUiMaterial<M>>();

    for (entity, extracted_uinode) in extracted_uinodes.uinodes.iter() {
        let Some(material) = render_materials.get(extracted_uinode.material) else {
            continue;
        };
        let Ok((view, mut transparent_phase)) = views.get_mut(extracted_uinode.camera_entity)
        else {
            continue;
        };

        let pipeline = pipelines.specialize(
            &pipeline_cache,
            &ui_material_pipeline,
            UiMaterialKey {
                hdr: view.hdr,
                bind_group_data: material.key.clone(),
            },
        );
        transparent_phase
            .items
            .reserve(extracted_uinodes.uinodes.len());
        transparent_phase.add(TransparentUi {
            draw_function,
            pipeline,
            entity: *entity,
            sort_key: (
                FloatOrd(extracted_uinode.stack_index as f32),
                entity.index(),
            ),
            batch_range: 0..0,
            dynamic_offset: None,
        });
    }
}