viewport-lib 0.12.1

//! Dynamic resolution render target for the LDR render path.
//!
//! When `render_scale < 1.0`, the scene is rendered into a scaled intermediate
//! texture and then upscaled to the surface via bilinear filtering.

use super::ViewportGpuResources;

/// Per-viewport intermediate render target for dynamic resolution rendering.
///
/// Owned by the viewport slot; created or recreated whenever the render scale
/// or surface size changes.
pub(crate) struct DynResTarget {
    /// Scaled color texture (render_scale × surface_size).
    pub _color_texture: wgpu::Texture,
    /// View of `color_texture`.
    pub color_view: wgpu::TextureView,
    /// Depth texture matching the scaled resolution.
    pub _depth_texture: wgpu::Texture,
    /// View of `depth_texture`.
    pub depth_view: wgpu::TextureView,
    /// Bind group for the upscale pass: color_texture + linear sampler.
    pub upscale_bind_group: wgpu::BindGroup,
    /// Dimensions of the intermediate target `[w, h]`.
    pub scaled_size: [u32; 2],
    /// Native surface dimensions this target was created for `[w, h]`.
    pub surface_size: [u32; 2],
}

impl ViewportGpuResources {
    /// Ensure the shared upscale pipeline and sampler exist, creating them on
    /// first call. Idempotent.
    pub(crate) fn ensure_dyn_res_pipeline(&mut self, device: &wgpu::Device) {
        if self.dyn_res_upscale_pipeline.is_some() {
            return;
        }

        let bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("dyn_res_upscale_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 sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            label: Some("dyn_res_linear_sampler"),
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            address_mode_w: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            mipmap_filter: wgpu::FilterMode::Nearest,
            ..Default::default()
        });

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

        let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("dyn_res_upscale_layout"),
            bind_group_layouts: &[&bgl],
            push_constant_ranges: &[],
        });

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

        self.dyn_res_upscale_bgl = Some(bgl);
        self.dyn_res_upscale_pipeline = Some(pipeline);
        self.dyn_res_linear_sampler = Some(sampler);
    }

    /// Create a [`DynResTarget`] at `scaled_size`, bound for upscaling to
    /// `surface_size`. The shared pipeline must already exist (call
    /// [`ensure_dyn_res_pipeline`](Self::ensure_dyn_res_pipeline) first).
    pub(crate) fn create_dyn_res_target(
        &self,
        device: &wgpu::Device,
        scaled_size: [u32; 2],
        surface_size: [u32; 2],
    ) -> DynResTarget {
        let [sw, sh] = scaled_size;

        let color_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("dyn_res_color"),
            size: wgpu::Extent3d { width: sw, height: sh, depth_or_array_layers: 1 },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: self.target_format,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
            view_formats: &[],
        });
        let color_view = color_texture.create_view(&wgpu::TextureViewDescriptor::default());

        let depth_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("dyn_res_depth"),
            size: wgpu::Extent3d { width: sw, height: sh, depth_or_array_layers: 1 },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Depth24PlusStencil8,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            view_formats: &[],
        });
        let depth_view = depth_texture.create_view(&wgpu::TextureViewDescriptor::default());

        let bgl = self.dyn_res_upscale_bgl.as_ref().unwrap();
        let sampler = self.dyn_res_linear_sampler.as_ref().unwrap();
        let upscale_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("dyn_res_upscale_bg"),
            layout: bgl,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&color_view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(sampler),
                },
            ],
        });

        DynResTarget {
            _color_texture: color_texture,
            color_view,
            _depth_texture: depth_texture,
            depth_view,
            upscale_bind_group,
            scaled_size,
            surface_size,
        }
    }
}