cad-editor/src/scene/pipeline/mod.rs

pub mod hatch_gpu;
pub mod image_gpu;
pub mod mesh_gpu;
pub mod uniforms;
pub mod viewcube;
pub mod wire_gpu;

use iced::wgpu;
use iced::{Rectangle, Size};

pub use hatch_gpu::HatchGpu;
pub use image_gpu::ImageGpu;
pub use mesh_gpu::MeshGpu;
pub use uniforms::Uniforms;
pub use viewcube::ViewCubePipeline;
pub use wire_gpu::WireGpu;

use crate::scene::hatch_model::HatchModel;
use crate::scene::image_model::ImageModel;
use crate::scene::mesh_model::MeshModel;
use crate::scene::wire_model::WireModel;

/// MSAA sample count for the main drawing pipelines.
const MSAA_SAMPLES: u32 = 4;

pub struct Pipeline {
    wire_pipeline: wgpu::RenderPipeline,
    hatch_pipeline: wgpu::RenderPipeline,
    image_pipeline: wgpu::RenderPipeline,
    mesh_pipeline: wgpu::RenderPipeline,
    uniform_buffer: wgpu::Buffer,
    uniform_bind_group: wgpu::BindGroup,
    hatch_bgl1: wgpu::BindGroupLayout,
    image_bgl1: wgpu::BindGroupLayout,
    depth_texture_size: Size<u32>,
    depth_view: wgpu::TextureView,
    /// 4× MSAA color buffer for the main drawing passes.
    msaa_view: wgpu::TextureView,
    /// Single-sample texture that receives the MSAA resolve result.
    resolve_view: wgpu::TextureView,
    /// Pipeline + resources for blitting the resolve texture to the surface target.
    blit_pipeline: wgpu::RenderPipeline,
    blit_bind_group_layout: wgpu::BindGroupLayout,
    blit_sampler: wgpu::Sampler,
    blit_bind_group: wgpu::BindGroup,
    /// Cached texture format (needed to recreate MSAA / depth textures on resize).
    surface_format: wgpu::TextureFormat,
    gpu_wires: Vec<WireGpu>,
    gpu_hatches: Vec<HatchGpu>,
    /// Wipeout fills — rendered after wires in a separate pass.
    gpu_wipeouts: Vec<HatchGpu>,
    gpu_images: Vec<ImageGpu>,
    gpu_meshes: Vec<MeshGpu>,
    pub viewcube: ViewCubePipeline,
    /// Last geometry epoch for which GPU buffers were uploaded.
    /// Initialized to u64::MAX so the first frame always uploads.
    pub cached_epoch: u64,
}

impl Pipeline {
    pub fn new(device: &wgpu::Device, queue: &wgpu::Queue, format: wgpu::TextureFormat) -> Self {
        // ── Shared frame uniform buffer (view_proj etc.) ───────────────────
        let uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("viewer.uniform_buffer"),
            size: std::mem::size_of::<Uniforms>() as u64,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        // Bind group layout 0 — shared by wire and hatch pipelines.
        let frame_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("viewer.frame_bgl"),
            entries: &[wgpu::BindGroupLayoutEntry {
                binding: 0,
                visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
                ty: wgpu::BindingType::Buffer {
                    ty: wgpu::BufferBindingType::Uniform,
                    has_dynamic_offset: false,
                    min_binding_size: None,
                },
                count: None,
            }],
        });

        let uniform_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("viewer.bind_group"),
            layout: &frame_bgl,
            entries: &[wgpu::BindGroupEntry {
                binding: 0,
                resource: uniform_buffer.as_entire_binding(),
            }],
        });

        // ── Wire pipeline ──────────────────────────────────────────────────
        let wire_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("wire.pipeline_layout"),
            bind_group_layouts: &[&frame_bgl],
            push_constant_ranges: &[],
        });

        let depth_tex = create_depth_texture(device, Size::new(1, 1));
        let depth_view = depth_tex.create_view(&wgpu::TextureViewDescriptor::default());

        let wire_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("wire.shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "../../shaders/wire.wgsl"
            ))),
        });

        let wire_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("wire.pipeline"),
            layout: Some(&wire_layout),
            vertex: wgpu::VertexState {
                module: &wire_shader,
                entry_point: Some("vs_main"),
                buffers: &[wire_gpu::WireVertex::layout()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                cull_mode: None,
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: true,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: MSAA_SAMPLES,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            fragment: Some(wgpu::FragmentState {
                module: &wire_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            multiview: None,
            cache: None,
        });

        // ── Hatch pipeline ─────────────────────────────────────────────────
        let hatch_entry = |binding: u32| wgpu::BindGroupLayoutEntry {
            binding,
            visibility: wgpu::ShaderStages::FRAGMENT,
            ty: wgpu::BindingType::Buffer {
                ty: wgpu::BufferBindingType::Uniform,
                has_dynamic_offset: false,
                min_binding_size: None,
            },
            count: None,
        };
        let hatch_bgl1 = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("hatch.bgl1"),
            entries: &[hatch_entry(0), hatch_entry(1), hatch_entry(2)],
        });

        let hatch_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("hatch.pipeline_layout"),
            bind_group_layouts: &[&frame_bgl, &hatch_bgl1],
            push_constant_ranges: &[],
        });

        let hatch_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("hatch.shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "../../shaders/hatch.wgsl"
            ))),
        });

        let hatch_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("hatch.pipeline"),
            layout: Some(&hatch_layout),
            vertex: wgpu::VertexState {
                module: &hatch_shader,
                entry_point: Some("vs_main"),
                buffers: &[hatch_gpu::HatchVertex::layout()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                cull_mode: None,
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: true,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: MSAA_SAMPLES,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            fragment: Some(wgpu::FragmentState {
                module: &hatch_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            multiview: None,
            cache: None,
        });

        // ── Mesh pipeline ──────────────────────────────────────────────────
        let mesh_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("mesh.shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "../../shaders/mesh.wgsl"
            ))),
        });

        let mesh_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("mesh.pipeline_layout"),
            bind_group_layouts: &[&frame_bgl],
            push_constant_ranges: &[],
        });

        let mesh_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("mesh.pipeline"),
            layout: Some(&mesh_layout),
            vertex: wgpu::VertexState {
                module: &mesh_shader,
                entry_point: Some("vs_main"),
                buffers: &[mesh_gpu::MeshVertex::layout()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                cull_mode: Some(wgpu::Face::Back),
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: true,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: MSAA_SAMPLES,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            fragment: Some(wgpu::FragmentState {
                module: &mesh_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            multiview: None,
            cache: None,
        });

        // ── Image pipeline ─────────────────────────────────────────────────
        let image_bgl1 = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("image.bgl1"),
            entries: &[
                // binding 0: texture
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Texture {
                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        view_dimension: wgpu::TextureViewDimension::D2,
                        multisampled: false,
                    },
                    count: None,
                },
                // binding 1: sampler
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
                // binding 2: ImageParams uniform
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                },
            ],
        });

        let image_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("image.pipeline_layout"),
            bind_group_layouts: &[&frame_bgl, &image_bgl1],
            push_constant_ranges: &[],
        });

        let image_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("image.shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "../../shaders/image.wgsl"
            ))),
        });

        let image_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("image.pipeline"),
            layout: Some(&image_layout),
            vertex: wgpu::VertexState {
                module: &image_shader,
                entry_point: Some("vs_main"),
                buffers: &[image_gpu::ImageVertex::layout()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                cull_mode: None,
                ..Default::default()
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: true,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: MSAA_SAMPLES,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            fragment: Some(wgpu::FragmentState {
                module: &image_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            multiview: None,
            cache: None,
        });

        let viewcube = ViewCubePipeline::new(device, queue, format);

        let init_size = Size::new(1, 1);
        let msaa_view = create_msaa_texture(device, init_size, format)
            .create_view(&wgpu::TextureViewDescriptor::default());
        let resolve_tex = create_resolve_texture(device, init_size, format);
        let resolve_view = resolve_tex.create_view(&wgpu::TextureViewDescriptor::default());

        // ── Blit pipeline (resolve texture → surface target) ──────────────
        let blit_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("blit.shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "../../shaders/blit.wgsl"
            ))),
        });

        let blit_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("blit.bgl"),
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Texture {
                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        view_dimension: wgpu::TextureViewDimension::D2,
                        multisampled: false,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
            ],
        });

        let blit_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("blit.pipeline_layout"),
            bind_group_layouts: &[&blit_bgl],
            push_constant_ranges: &[],
        });

        let blit_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("blit.pipeline"),
            layout: Some(&blit_layout),
            vertex: wgpu::VertexState {
                module: &blit_shader,
                entry_point: Some("vs_main"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                ..Default::default()
            },
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            fragment: Some(wgpu::FragmentState {
                module: &blit_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            multiview: None,
            cache: None,
        });

        let blit_sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            label: Some("blit.sampler"),
            mag_filter: wgpu::FilterMode::Nearest,
            min_filter: wgpu::FilterMode::Nearest,
            ..Default::default()
        });

        let blit_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("blit.bind_group"),
            layout: &blit_bgl,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&resolve_view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&blit_sampler),
                },
            ],
        });

        Self {
            wire_pipeline,
            hatch_pipeline,
            image_pipeline,
            mesh_pipeline,
            uniform_buffer,
            uniform_bind_group,
            hatch_bgl1,
            image_bgl1,
            depth_texture_size: Size::new(1, 1),
            depth_view,
            msaa_view,
            resolve_view,
            blit_pipeline,
            blit_bind_group_layout: blit_bgl,
            blit_sampler,
            blit_bind_group,
            surface_format: format,
            gpu_wires: vec![],
            gpu_hatches: vec![],
            gpu_wipeouts: vec![],
            gpu_images: vec![],
            gpu_meshes: vec![],
            viewcube,
            cached_epoch: u64::MAX,
        }
    }

    pub fn upload_wires(&mut self, device: &wgpu::Device, wires: &[WireModel]) {
        self.gpu_wires = wires.iter().map(|w| WireGpu::new(device, w)).collect();
    }

    pub fn upload_meshes(&mut self, device: &wgpu::Device, meshes: &[MeshModel]) {
        self.gpu_meshes = meshes
            .iter()
            .filter(|m| !m.indices.is_empty())
            .map(|m| MeshGpu::new(device, m))
            .collect();
    }

    pub fn upload_hatches(&mut self, device: &wgpu::Device, hatches: &[HatchModel]) {
        self.gpu_hatches = hatches
            .iter()
            .filter(|h| h.boundary.len() >= 3)
            .map(|h| HatchGpu::new(device, h, &self.hatch_bgl1))
            .collect();
    }

    pub fn upload_wipeouts(&mut self, device: &wgpu::Device, wipeouts: &[HatchModel]) {
        self.gpu_wipeouts = wipeouts
            .iter()
            .filter(|h| h.boundary.len() >= 3)
            .map(|h| HatchGpu::new(device, h, &self.hatch_bgl1))
            .collect();
    }

    pub fn upload_images(
        &mut self,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
        images: &[ImageModel],
    ) {
        self.gpu_images = images
            .iter()
            .filter_map(|m| ImageGpu::new(device, queue, m, &self.image_bgl1))
            .collect();
    }

    pub fn upload_uniforms(&self, queue: &wgpu::Queue, uniforms: &Uniforms) {
        queue.write_buffer(&self.uniform_buffer, 0, bytemuck::bytes_of(uniforms));
    }

    pub fn render(
        &self,
        encoder: &mut wgpu::CommandEncoder,
        target: &wgpu::TextureView,
        clip_bounds: Rectangle<u32>,
        bg_color: [f32; 4],
    ) {
        let vp = clip_bounds;
        let msaa = &self.msaa_view;
        let [r, g, b, a] = bg_color;
        let clear_color = wgpu::Color { r: r as f64, g: g as f64, b: b as f64, a: a as f64 };

        // ── Pass 1: hatch fills ────────────────────────────────────────────
        {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("hatch.render_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: msaa,
                    depth_slice: None,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        // Clear MSAA to background color on the first pass.
                        load: wgpu::LoadOp::Clear(clear_color),
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Clear(1.0),
                        store: wgpu::StoreOp::Store,
                    }),
                    stencil_ops: None,
                }),
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            // MSAA texture is clip-bounds-sized, so viewport starts at (0, 0).
            pass.set_viewport(0.0, 0.0, vp.width as f32, vp.height as f32, 0.0, 1.0);
            if !self.gpu_hatches.is_empty() {
                pass.set_pipeline(&self.hatch_pipeline);
                pass.set_bind_group(0, &self.uniform_bind_group, &[]);
                for hatch in &self.gpu_hatches {
                    pass.set_bind_group(1, &hatch.bind_group, &[]);
                    pass.set_vertex_buffer(0, hatch.vertex_buffer.slice(..));
                    pass.draw(0..6, 0..1);
                }
            }
        }

        // ── Pass 2: raster images ─────────────────────────────────────────
        if !self.gpu_images.is_empty() {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("image.render_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: msaa,
                    depth_slice: None,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    }),
                    stencil_ops: None,
                }),
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            pass.set_viewport(0.0, 0.0, vp.width as f32, vp.height as f32, 0.0, 1.0);
            pass.set_pipeline(&self.image_pipeline);
            pass.set_bind_group(0, &self.uniform_bind_group, &[]);
            for img in &self.gpu_images {
                pass.set_bind_group(1, &img.bind_group, &[]);
                pass.set_vertex_buffer(0, img.vertex_buffer.slice(..));
                pass.draw(0..6, 0..1);
            }
        }

        // ── Pass 4: solid meshes ──────────────────────────────────────────
        if !self.gpu_meshes.is_empty() {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("mesh.render_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: msaa,
                    depth_slice: None,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    }),
                    stencil_ops: None,
                }),
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            pass.set_viewport(0.0, 0.0, vp.width as f32, vp.height as f32, 0.0, 1.0);
            pass.set_pipeline(&self.mesh_pipeline);
            pass.set_bind_group(0, &self.uniform_bind_group, &[]);
            for mesh in &self.gpu_meshes {
                if mesh.index_count > 0 {
                    pass.set_vertex_buffer(0, mesh.vertex_buffer.slice(..));
                    pass.set_index_buffer(mesh.index_buffer.slice(..), wgpu::IndexFormat::Uint32);
                    pass.draw_indexed(0..mesh.index_count, 0, 0..1);
                }
            }
        }

        // ── Pass 5: wires ─────────────────────────────────────────────────
        {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("wire.render_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: msaa,
                    depth_slice: None,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    }),
                    stencil_ops: None,
                }),
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            pass.set_viewport(0.0, 0.0, vp.width as f32, vp.height as f32, 0.0, 1.0);
            pass.set_pipeline(&self.wire_pipeline);
            pass.set_bind_group(0, &self.uniform_bind_group, &[]);
            for wire in &self.gpu_wires {
                if wire.vertex_count >= 6 {
                    pass.set_vertex_buffer(0, wire.vertex_buffer.slice(..));
                    pass.draw(0..wire.vertex_count, 0..1);
                }
            }
        }

        // ── Pass 6: wipeout fills (drawn after wires to mask them) ────────
        if !self.gpu_wipeouts.is_empty() {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("wipeout.render_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: msaa,
                    depth_slice: None,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: &self.depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    }),
                    stencil_ops: None,
                }),
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            pass.set_viewport(0.0, 0.0, vp.width as f32, vp.height as f32, 0.0, 1.0);
            pass.set_pipeline(&self.hatch_pipeline);
            pass.set_bind_group(0, &self.uniform_bind_group, &[]);
            for wipeout in &self.gpu_wipeouts {
                pass.set_bind_group(1, &wipeout.bind_group, &[]);
                pass.set_vertex_buffer(0, wipeout.vertex_buffer.slice(..));
                pass.draw(0..6, 0..1);
            }
        }

        // ── Resolve MSAA → clip-sized resolve texture ─────────────────────
        // Both msaa_view and resolve_view are sized to clip_bounds, so the
        // resolve does NOT touch any pixels outside the shader widget's area.
        {
            let _resolve = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("msaa.resolve_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: msaa,
                    depth_slice: None,
                    resolve_target: Some(&self.resolve_view),
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Discard,
                    },
                })],
                depth_stencil_attachment: None,
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            // No draw calls — the pass itself triggers the MSAA resolve.
        }

        // ── Blit resolve texture → surface target at clip_bounds position ──
        // The viewport maps the full-screen NDC quad to exactly clip_bounds
        // in the surface, leaving all other widgets untouched.
        {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("blit.render_pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: target,
                    depth_slice: None,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Load,
                        store: wgpu::StoreOp::Store,
                    },
                })],
                depth_stencil_attachment: None,
                timestamp_writes: None,
                occlusion_query_set: None,
            });
            pass.set_viewport(
                vp.x as f32,
                vp.y as f32,
                vp.width as f32,
                vp.height as f32,
                0.0,
                1.0,
            );
            pass.set_pipeline(&self.blit_pipeline);
            pass.set_bind_group(0, &self.blit_bind_group, &[]);
            pass.draw(0..6, 0..1);
        }
    }

    pub fn ensure_depth_texture(&mut self, device: &wgpu::Device, size: Size<u32>) {
        if self.depth_texture_size != size {
            let depth_tex = create_depth_texture(device, size);
            self.depth_view = depth_tex.create_view(&wgpu::TextureViewDescriptor::default());
            let msaa_tex = create_msaa_texture(device, size, self.surface_format);
            self.msaa_view = msaa_tex.create_view(&wgpu::TextureViewDescriptor::default());
            let resolve_tex = create_resolve_texture(device, size, self.surface_format);
            let resolve_view = resolve_tex.create_view(&wgpu::TextureViewDescriptor::default());
            self.blit_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
                label: Some("blit.bind_group"),
                layout: &self.blit_bind_group_layout,
                entries: &[
                    wgpu::BindGroupEntry {
                        binding: 0,
                        resource: wgpu::BindingResource::TextureView(&resolve_view),
                    },
                    wgpu::BindGroupEntry {
                        binding: 1,
                        resource: wgpu::BindingResource::Sampler(&self.blit_sampler),
                    },
                ],
            });
            self.resolve_view = resolve_view;
            self.depth_texture_size = size;
        }
    }
}

fn create_depth_texture(device: &wgpu::Device, size: Size<u32>) -> wgpu::Texture {
    device.create_texture(&wgpu::TextureDescriptor {
        label: Some("viewer.depth_texture"),
        size: wgpu::Extent3d {
            width: size.width.max(1),
            height: size.height.max(1),
            depth_or_array_layers: 1,
        },
        mip_level_count: 1,
        sample_count: MSAA_SAMPLES,
        dimension: wgpu::TextureDimension::D2,
        format: wgpu::TextureFormat::Depth32Float,
        usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
        view_formats: &[],
    })
}

fn create_resolve_texture(
    device: &wgpu::Device,
    size: Size<u32>,
    format: wgpu::TextureFormat,
) -> wgpu::Texture {
    device.create_texture(&wgpu::TextureDescriptor {
        label: Some("viewer.resolve_texture"),
        size: wgpu::Extent3d {
            width: size.width.max(1),
            height: size.height.max(1),
            depth_or_array_layers: 1,
        },
        mip_level_count: 1,
        sample_count: 1,
        dimension: wgpu::TextureDimension::D2,
        format,
        usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
        view_formats: &[],
    })
}

fn create_msaa_texture(
    device: &wgpu::Device,
    size: Size<u32>,
    format: wgpu::TextureFormat,
) -> wgpu::Texture {
    device.create_texture(&wgpu::TextureDescriptor {
        label: Some("viewer.msaa_texture"),
        size: wgpu::Extent3d {
            width: size.width.max(1),
            height: size.height.max(1),
            depth_or_array_layers: 1,
        },
        mip_level_count: 1,
        sample_count: MSAA_SAMPLES,
        dimension: wgpu::TextureDimension::D2,
        format,
        usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
        view_formats: &[],
    })
}

impl iced::widget::shader::Pipeline for Pipeline {
    fn new(device: &wgpu::Device, queue: &wgpu::Queue, format: wgpu::TextureFormat) -> Self {
        Self::new(device, queue, format)
    }
}