polyscope_render/

ssao_pass.rs

//! SSAO (Screen Space Ambient Occlusion) rendering pass.

use glam::Mat4;
use std::num::NonZeroU64;
use wgpu::util::DeviceExt;

/// GPU representation of SSAO uniforms.
#[repr(C)]
#[derive(Debug, Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
#[allow(clippy::pub_underscore_fields)]
pub struct SsaoUniforms {
    pub proj: [[f32; 4]; 4],
    pub inv_proj: [[f32; 4]; 4],
    pub radius: f32,
    pub bias: f32,
    pub intensity: f32,
    pub sample_count: u32,
    pub screen_width: f32,
    pub screen_height: f32,
    pub _padding: [f32; 2],
}

impl Default for SsaoUniforms {
    fn default() -> Self {
        Self {
            proj: Mat4::IDENTITY.to_cols_array_2d(),
            inv_proj: Mat4::IDENTITY.to_cols_array_2d(),
            radius: 0.5,
            bias: 0.025,
            intensity: 1.0,
            sample_count: 16,
            screen_width: 1280.0,
            screen_height: 720.0,
            _padding: [0.0; 2],
        }
    }
}

/// SSAO blur uniforms.
#[repr(C)]
#[derive(Debug, Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
#[allow(clippy::pub_underscore_fields)]
pub struct SsaoBlurUniforms {
    pub texel_size: [f32; 2],
    pub blur_scale: f32,
    /// Controls edge preservation (higher = sharper edges preserved)
    pub blur_sharpness: f32,
}

/// SSAO pass resources.
pub struct SsaoPass {
    // Main SSAO pass
    ssao_pipeline: wgpu::RenderPipeline,
    ssao_bind_group_layout: wgpu::BindGroupLayout,
    ssao_uniform_buffer: wgpu::Buffer,
    // Blur pass
    blur_pipeline: wgpu::RenderPipeline,
    blur_bind_group_layout: wgpu::BindGroupLayout,
    blur_uniform_buffer: wgpu::Buffer,
    // Intermediate texture for blur
    ssao_texture: wgpu::Texture,
    ssao_view: wgpu::TextureView,
    // Sampler
    sampler: wgpu::Sampler,
}

impl SsaoPass {
    /// Creates a new SSAO pass.
    #[must_use]
    pub fn new(device: &wgpu::Device, width: u32, height: u32) -> Self {
        // Create SSAO shader
        let ssao_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("SSAO Shader"),
            source: wgpu::ShaderSource::Wgsl(include_str!("shaders/ssao.wgsl").into()),
        });

        // Create blur shader
        let blur_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("SSAO Blur Shader"),
            source: wgpu::ShaderSource::Wgsl(include_str!("shaders/ssao_blur.wgsl").into()),
        });

        // SSAO bind group layout
        let ssao_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("SSAO Bind Group Layout"),
                entries: &[
                    // Depth texture
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            sample_type: wgpu::TextureSampleType::Depth,
                            view_dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    // Normal texture
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                            view_dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    // Noise texture
                    wgpu::BindGroupLayoutEntry {
                        binding: 2,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                            view_dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    // Sampler
                    wgpu::BindGroupLayoutEntry {
                        binding: 3,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                        count: None,
                    },
                    // Uniforms
                    wgpu::BindGroupLayoutEntry {
                        binding: 4,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Uniform,
                            has_dynamic_offset: false,
                            min_binding_size: NonZeroU64::new(160),
                        },
                        count: None,
                    },
                ],
            });

        // SSAO pipeline
        let ssao_pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("SSAO Pipeline Layout"),
            bind_group_layouts: &[&ssao_bind_group_layout],
            push_constant_ranges: &[],
        });

        let ssao_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("SSAO Pipeline"),
            layout: Some(&ssao_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &ssao_shader,
                entry_point: Some("vs_main"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &ssao_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::R8Unorm, // Single channel for occlusion
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                ..Default::default()
            },
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview: None,
            cache: None,
        });

        // Blur bind group layout - now includes depth texture for edge-aware blurring
        let blur_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("SSAO Blur Bind Group Layout"),
                entries: &[
                    // SSAO texture (binding 0)
                    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,
                    },
                    // Depth texture (binding 1) - for edge-aware bilateral blur
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            sample_type: wgpu::TextureSampleType::Depth,
                            view_dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    // Sampler (binding 2)
                    wgpu::BindGroupLayoutEntry {
                        binding: 2,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                        count: None,
                    },
                    // Uniforms (binding 3)
                    wgpu::BindGroupLayoutEntry {
                        binding: 3,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Uniform,
                            has_dynamic_offset: false,
                            min_binding_size: NonZeroU64::new(16),
                        },
                        count: None,
                    },
                ],
            });

        // Blur pipeline
        let blur_pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("SSAO Blur Pipeline Layout"),
            bind_group_layouts: &[&blur_bind_group_layout],
            push_constant_ranges: &[],
        });

        let blur_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("SSAO Blur Pipeline"),
            layout: Some(&blur_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &blur_shader,
                entry_point: Some("vs_main"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &blur_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::R8Unorm,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::TriangleList,
                ..Default::default()
            },
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview: None,
            cache: None,
        });

        // Create uniform buffers
        let ssao_uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("SSAO Uniform Buffer"),
            contents: bytemuck::cast_slice(&[SsaoUniforms::default()]),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

        let blur_uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("SSAO Blur Uniform Buffer"),
            contents: bytemuck::cast_slice(&[SsaoBlurUniforms {
                texel_size: [1.0 / width as f32, 1.0 / height as f32],
                blur_scale: 1.0,
                blur_sharpness: 50.0, // Edge preservation strength
            }]),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

        // Create intermediate SSAO texture
        let ssao_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("SSAO Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::R8Unorm,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
            view_formats: &[],
        });

        let ssao_view = ssao_texture.create_view(&wgpu::TextureViewDescriptor::default());

        // Create sampler
        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            label: Some("SSAO Sampler"),
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            ..Default::default()
        });

        Self {
            ssao_pipeline,
            ssao_bind_group_layout,
            ssao_uniform_buffer,
            blur_pipeline,
            blur_bind_group_layout,
            blur_uniform_buffer,
            ssao_texture,
            ssao_view,
            sampler,
        }
    }

    /// Resizes the SSAO textures.
    pub fn resize(&mut self, device: &wgpu::Device, queue: &wgpu::Queue, width: u32, height: u32) {
        // Recreate SSAO texture
        self.ssao_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("SSAO Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::R8Unorm,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
            view_formats: &[],
        });

        self.ssao_view = self
            .ssao_texture
            .create_view(&wgpu::TextureViewDescriptor::default());

        // Update blur uniforms
        queue.write_buffer(
            &self.blur_uniform_buffer,
            0,
            bytemuck::cast_slice(&[SsaoBlurUniforms {
                texel_size: [1.0 / width as f32, 1.0 / height as f32],
                blur_scale: 1.0,
                blur_sharpness: 50.0,
            }]),
        );
    }

    /// Updates SSAO uniforms.
    pub fn update_uniforms(
        &self,
        queue: &wgpu::Queue,
        proj: Mat4,
        inv_proj: Mat4,
        radius: f32,
        bias: f32,
        intensity: f32,
        sample_count: u32,
        width: f32,
        height: f32,
    ) {
        let uniforms = SsaoUniforms {
            proj: proj.to_cols_array_2d(),
            inv_proj: inv_proj.to_cols_array_2d(),
            radius,
            bias,
            intensity,
            sample_count,
            screen_width: width,
            screen_height: height,
            _padding: [0.0; 2],
        };
        queue.write_buffer(
            &self.ssao_uniform_buffer,
            0,
            bytemuck::cast_slice(&[uniforms]),
        );
    }

    /// Creates a bind group for the SSAO pass.
    #[must_use]
    pub fn create_ssao_bind_group(
        &self,
        device: &wgpu::Device,
        depth_view: &wgpu::TextureView,
        normal_view: &wgpu::TextureView,
        noise_view: &wgpu::TextureView,
    ) -> wgpu::BindGroup {
        device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("SSAO Bind Group"),
            layout: &self.ssao_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(depth_view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::TextureView(normal_view),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: wgpu::BindingResource::TextureView(noise_view),
                },
                wgpu::BindGroupEntry {
                    binding: 3,
                    resource: wgpu::BindingResource::Sampler(&self.sampler),
                },
                wgpu::BindGroupEntry {
                    binding: 4,
                    resource: self.ssao_uniform_buffer.as_entire_binding(),
                },
            ],
        })
    }

    /// Creates a bind group for the blur pass.
    /// The `depth_view` is used for edge-aware bilateral blurring.
    #[must_use]
    pub fn create_blur_bind_group(
        &self,
        device: &wgpu::Device,
        depth_view: &wgpu::TextureView,
    ) -> wgpu::BindGroup {
        device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("SSAO Blur Bind Group"),
            layout: &self.blur_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&self.ssao_view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::TextureView(depth_view),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: wgpu::BindingResource::Sampler(&self.sampler),
                },
                wgpu::BindGroupEntry {
                    binding: 3,
                    resource: self.blur_uniform_buffer.as_entire_binding(),
                },
            ],
        })
    }

    /// Renders the SSAO pass.
    pub fn render_ssao(&self, encoder: &mut wgpu::CommandEncoder, bind_group: &wgpu::BindGroup) {
        let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
            label: Some("SSAO Pass"),
            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                view: &self.ssao_view,
                resolve_target: None,
                ops: wgpu::Operations {
                    load: wgpu::LoadOp::Clear(wgpu::Color::WHITE),
                    store: wgpu::StoreOp::Store,
                },
                depth_slice: None,
            })],
            depth_stencil_attachment: None,
            ..Default::default()
        });

        render_pass.set_pipeline(&self.ssao_pipeline);
        render_pass.set_bind_group(0, bind_group, &[]);
        render_pass.draw(0..3, 0..1);
    }

    /// Renders the blur pass to the output texture.
    pub fn render_blur(
        &self,
        encoder: &mut wgpu::CommandEncoder,
        output_view: &wgpu::TextureView,
        bind_group: &wgpu::BindGroup,
    ) {
        let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
            label: Some("SSAO Blur Pass"),
            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                view: output_view,
                resolve_target: None,
                ops: wgpu::Operations {
                    load: wgpu::LoadOp::Clear(wgpu::Color::WHITE),
                    store: wgpu::StoreOp::Store,
                },
                depth_slice: None,
            })],
            depth_stencil_attachment: None,
            ..Default::default()
        });

        render_pass.set_pipeline(&self.blur_pipeline);
        render_pass.set_bind_group(0, bind_group, &[]);
        render_pass.draw(0..3, 0..1);
    }

    /// Returns the blurred SSAO texture view.
    #[must_use]
    pub fn ssao_view(&self) -> &wgpu::TextureView {
        &self.ssao_view
    }
}