gled 2.29.0

//! Render preview circles.
use super::preview_indices::PreviewIndices;
use crate::{
    pipeline::constants::{OUTPUT_BUFFER_SIZE, PREVIEW_INDICES_BUFFER_SIZE, PREVIEW_TEXTURE_SIZE},
    wgpu_render_state,
};
use egui::TextureId;
use std::{num::NonZeroU64, sync::OnceLock};
use wgpu::{
    BindGroup, BindGroupDescriptor, BindGroupEntry, BindGroupLayoutDescriptor,
    BindGroupLayoutEntry, BindingType, Buffer, BufferBindingType, BufferDescriptor, BufferUsages,
    CommandEncoder, Extent3d, FragmentState, LoadOp, MultisampleState, Operations,
    PipelineLayoutDescriptor, PrimitiveState, Queue, RenderPassColorAttachment,
    RenderPassDescriptor, RenderPipeline, RenderPipelineDescriptor, ShaderModuleDescriptor,
    ShaderSource, ShaderStages, StoreOp, TextureDescriptor, TextureDimension, TextureFormat,
    TextureUsages, TextureView, TextureViewDescriptor, VertexState,
};

/// Preview resources on the UI device. Only used on the UI thread.
static PREVIEW: OnceLock<Preview> = OnceLock::new();

#[derive(Debug)]
pub struct Preview {
    /// UI-device copy of the LED output, uploaded from the render thread's readback.
    output: Buffer,
    pipeline: RenderPipeline,
    bind_group: BindGroup,
    view: TextureView,
    texture_id: TextureId,
}

impl Preview {
    fn init() -> Self {
        let texture_desc = TextureDescriptor {
            size: Extent3d {
                width: PREVIEW_TEXTURE_SIZE as u32,
                height: PREVIEW_TEXTURE_SIZE as u32,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: TextureDimension::D2,
            format: TextureFormat::Bgra8Unorm,
            usage: TextureUsages::COPY_SRC
                | TextureUsages::RENDER_ATTACHMENT
                | TextureUsages::TEXTURE_BINDING,
            label: None,
            view_formats: &[TextureFormat::Bgra8Unorm],
        };

        let wgpu_render_state = wgpu_render_state();
        let device = wgpu_render_state.device;

        let texture = device.create_texture(&texture_desc);
        let view = texture.create_view(&TextureViewDescriptor::default());

        let output = device.create_buffer(&BufferDescriptor {
            size: OUTPUT_BUFFER_SIZE,
            usage: BufferUsages::STORAGE | BufferUsages::COPY_DST,
            label: Some("Preview output buffer"),
            mapped_at_creation: false,
        });

        let vertex_shader = device.create_shader_module(ShaderModuleDescriptor {
            label: Some("preview vertex shader"),
            source: ShaderSource::Wgsl(include_str!("../shaders/vertex.wgsl").into()),
        });

        let fragment_shader = device.create_shader_module(ShaderModuleDescriptor {
            label: Some("preview fragment shader"),
            source: ShaderSource::Wgsl(include_str!("../shaders/preview.wgsl").into()),
        });

        let bind_group_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
            label: Some("preview bind group layout"),
            entries: &[
                BindGroupLayoutEntry {
                    binding: 0,
                    visibility: ShaderStages::FRAGMENT,
                    ty: BindingType::Buffer {
                        ty: BufferBindingType::Storage { read_only: true },
                        has_dynamic_offset: false,
                        min_binding_size: NonZeroU64::new(PREVIEW_INDICES_BUFFER_SIZE),
                    },
                    count: None,
                },
                BindGroupLayoutEntry {
                    binding: 1,
                    visibility: ShaderStages::FRAGMENT,
                    ty: BindingType::Buffer {
                        ty: BufferBindingType::Storage { read_only: true },
                        has_dynamic_offset: false,
                        min_binding_size: NonZeroU64::new(OUTPUT_BUFFER_SIZE),
                    },
                    count: None,
                },
            ],
        });

        let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
            label: Some("preview pipeline layout"),
            bind_group_layouts: &[Some(&bind_group_layout)],
            immediate_size: 0,
        });

        let pipeline = device.create_render_pipeline(&RenderPipelineDescriptor {
            cache: None,
            label: Some("preview pipeline"),
            layout: Some(&pipeline_layout),
            vertex: VertexState {
                module: &vertex_shader,
                entry_point: Some("vs_main"),
                buffers: &[],
                compilation_options: Default::default(),
            },
            fragment: Some(FragmentState {
                module: &fragment_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(TextureFormat::Bgra8Unorm.into())],
                compilation_options: Default::default(),
            }),
            primitive: PrimitiveState::default(),
            depth_stencil: None,
            multisample: MultisampleState::default(),
            multiview_mask: None,
        });

        let texture_id = wgpu_render_state.renderer.write().register_native_texture(
            &device,
            &view,
            wgpu::FilterMode::Nearest,
        );

        let bind_group = device.create_bind_group(&BindGroupDescriptor {
            label: Some("Preview bind group"),
            layout: &bind_group_layout,
            entries: &[
                BindGroupEntry {
                    binding: 0,
                    resource: PreviewIndices::get().indices().as_entire_binding(),
                },
                BindGroupEntry {
                    binding: 1,
                    resource: output.as_entire_binding(),
                },
            ],
        });

        Self {
            output,
            pipeline,
            bind_group,
            view,
            texture_id,
        }
    }

    fn get() -> &'static Self {
        PREVIEW.get_or_init(Self::init)
    }

    #[cfg_attr(feature = "profiling", profiling::function)]
    pub fn run(encoder: &mut CommandEncoder) {
        let preview = Self::get();

        let mut render_pass = encoder.begin_render_pass(&RenderPassDescriptor {
            label: Some("Renderer Pass"),
            color_attachments: &[Some(RenderPassColorAttachment {
                view: &preview.view,
                resolve_target: None,
                depth_slice: None,
                ops: Operations {
                    load: LoadOp::Clear(wgpu::Color {
                        r: 0.0,
                        g: 0.0,
                        b: 0.0,
                        a: 1.0,
                    }),
                    store: StoreOp::Store,
                },
            })],
            depth_stencil_attachment: None,
            timestamp_writes: None,
            occlusion_query_set: None,
            multiview_mask: None,
        });
        render_pass.set_pipeline(&preview.pipeline);
        render_pass.set_bind_group(0, &preview.bind_group, &[]);
        render_pass.draw(0..3, 0..1);
    }

    /// Upload read-back output bytes (from offset 0) for the next `run`.
    pub fn upload_output(queue: &Queue, output: &[u8]) {
        let length = output.len().min(OUTPUT_BUFFER_SIZE as usize);
        if length == 0 {
            return;
        }
        queue.write_buffer(&Self::get().output, 0, &output[..length]);
    }

    /// Show no LED output, e.g. after the project was closed.
    pub fn clear_output(queue: &Queue) {
        queue.write_buffer(&Self::get().output, 0, &[0; OUTPUT_BUFFER_SIZE as usize]);
    }

    pub fn texture_id() -> TextureId {
        Self::get().texture_id
    }
}