feat(renderer): add RT shadow compute pipeline and integrate into lighting pass

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/voltex_renderer/src/deferred_lighting.wgsl

@@ -51,6 +51,8 @@ struct ShadowUniform {
 @group(2) @binding(4) var s_brdf_lut: sampler;
 @group(2) @binding(5) var t_ssgi: texture_2d<f32>;
 @group(2) @binding(6) var s_ssgi: sampler;
+@group(2) @binding(7) var t_rt_shadow: texture_2d<f32>;
+@group(2) @binding(8) var s_rt_shadow: sampler;
 
 // ── Vertex / Fragment structs ─────────────────────────────────────────────────
 
@@ -264,8 +266,8 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     // F0: base reflectivity; 0.04 for dielectrics, albedo for metals
     let F0 = mix(vec3<f32>(0.04, 0.04, 0.04), albedo, metallic);
 
-    // Shadow
-    let shadow_factor = calculate_shadow(world_pos);
+    // Shadow: sample RT shadow texture (1.0 = lit, 0.0 = shadowed)
+    let shadow_factor = textureSample(t_rt_shadow, s_rt_shadow, uv).r;
 
     // Accumulate contribution from all active lights
     var Lo = vec3<f32>(0.0);

crates/voltex_renderer/src/deferred_pipeline.rs

@@ -6,6 +6,7 @@ use crate::gbuffer::{
 };
 use crate::light::CameraUniform;
 use crate::ssgi::{SsgiUniform, SSGI_OUTPUT_FORMAT};
+use crate::rt_shadow::{RtShadowUniform, RT_SHADOW_FORMAT};
 
 /// Bind group layout for the G-Buffer pass camera uniform (dynamic offset, group 0).
 pub fn gbuffer_camera_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
@@ -270,6 +271,24 @@ pub fn lighting_shadow_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGro
                 ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                 count: None,
             },
+            // binding 7: RT shadow texture (R32Float → filterable float)
+            wgpu::BindGroupLayoutEntry {
+                binding: 7,
+                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 8: filtering sampler for RT shadow texture
+            wgpu::BindGroupLayoutEntry {
+                binding: 8,
+                visibility: wgpu::ShaderStages::FRAGMENT,
+                ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                count: None,
+            },
         ],
     })
 }
@@ -495,3 +514,105 @@ pub fn create_ssgi_pipeline(
         cache: None,
     })
 }
+
+// ── RT Shadow pipeline ────────────────────────────────────────────────────────
+
+/// Bind group layout for the RT shadow compute pass G-Buffer inputs (group 0).
+/// Bindings: position (non-filterable), normal (filterable) — both COMPUTE visibility.
+pub fn rt_shadow_gbuffer_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
+    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+        label: Some("RT Shadow GBuffer Bind Group Layout"),
+        entries: &[
+            // binding 0: position texture (Rgba32Float → non-filterable)
+            wgpu::BindGroupLayoutEntry {
+                binding: 0,
+                visibility: wgpu::ShaderStages::COMPUTE,
+                ty: wgpu::BindingType::Texture {
+                    sample_type: wgpu::TextureSampleType::Float { filterable: false },
+                    view_dimension: wgpu::TextureViewDimension::D2,
+                    multisampled: false,
+                },
+                count: None,
+            },
+            // binding 1: normal texture (filterable)
+            wgpu::BindGroupLayoutEntry {
+                binding: 1,
+                visibility: wgpu::ShaderStages::COMPUTE,
+                ty: wgpu::BindingType::Texture {
+                    sample_type: wgpu::TextureSampleType::Float { filterable: true },
+                    view_dimension: wgpu::TextureViewDimension::D2,
+                    multisampled: false,
+                },
+                count: None,
+            },
+        ],
+    })
+}
+
+/// Bind group layout for the RT shadow compute pass data (group 1).
+/// Bindings: TLAS, storage texture (R32Float write), RtShadowUniform — all COMPUTE visibility.
+pub fn rt_shadow_data_bind_group_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
+    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+        label: Some("RT Shadow Data Bind Group Layout"),
+        entries: &[
+            // binding 0: TLAS (acceleration structure)
+            wgpu::BindGroupLayoutEntry {
+                binding: 0,
+                visibility: wgpu::ShaderStages::COMPUTE,
+                ty: wgpu::BindingType::AccelerationStructure { vertex_return: false },
+                count: None,
+            },
+            // binding 1: shadow output texture (R32Float, write-only storage)
+            wgpu::BindGroupLayoutEntry {
+                binding: 1,
+                visibility: wgpu::ShaderStages::COMPUTE,
+                ty: wgpu::BindingType::StorageTexture {
+                    access: wgpu::StorageTextureAccess::WriteOnly,
+                    format: RT_SHADOW_FORMAT,
+                    view_dimension: wgpu::TextureViewDimension::D2,
+                },
+                count: None,
+            },
+            // binding 2: RtShadowUniform
+            wgpu::BindGroupLayoutEntry {
+                binding: 2,
+                visibility: wgpu::ShaderStages::COMPUTE,
+                ty: wgpu::BindingType::Buffer {
+                    ty: wgpu::BufferBindingType::Uniform,
+                    has_dynamic_offset: false,
+                    min_binding_size: wgpu::BufferSize::new(
+                        std::mem::size_of::<RtShadowUniform>() as u64,
+                    ),
+                },
+                count: None,
+            },
+        ],
+    })
+}
+
+/// Create the RT shadow compute pipeline.
+pub fn create_rt_shadow_pipeline(
+    device: &wgpu::Device,
+    gbuffer_layout: &wgpu::BindGroupLayout,
+    data_layout: &wgpu::BindGroupLayout,
+) -> wgpu::ComputePipeline {
+    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+        label: Some("RT Shadow Shader"),
+        source: wgpu::ShaderSource::Wgsl(include_str!("rt_shadow_shader.wgsl").into()),
+    });
+
+    let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+        label: Some("RT Shadow Pipeline Layout"),
+        bind_group_layouts: &[gbuffer_layout, data_layout],
+        immediate_size: 0,
+    });
+
+    device.create_compute_pipeline(&wgpu::ComputePipelineDescriptor {
+        label: Some("RT Shadow Compute Pipeline"),
+        layout: Some(&layout),
+        module: &shader,
+        entry_point: Some("cs_main"),
+        compilation_options: wgpu::PipelineCompilationOptions::default(),
+        cache: None,
+    })
+}

crates/voltex_renderer/src/lib.rs

@@ -17,6 +17,8 @@ pub mod gbuffer;
 pub mod fullscreen_quad;
 pub mod deferred_pipeline;
 pub mod ssgi;
+pub mod rt_accel;
+pub mod rt_shadow;
 
 pub use gpu::{GpuContext, DEPTH_FORMAT};
 pub use light::{CameraUniform, LightUniform, LightData, LightsUniform, MAX_LIGHTS, LIGHT_DIRECTIONAL, LIGHT_POINT, LIGHT_SPOT};
@@ -36,5 +38,8 @@ pub use deferred_pipeline::{
     gbuffer_camera_bind_group_layout,
     lighting_gbuffer_bind_group_layout, lighting_lights_bind_group_layout, lighting_shadow_bind_group_layout,
     ssgi_gbuffer_bind_group_layout, ssgi_data_bind_group_layout, create_ssgi_pipeline,
+    rt_shadow_gbuffer_bind_group_layout, rt_shadow_data_bind_group_layout, create_rt_shadow_pipeline,
 };
 pub use ssgi::{SsgiResources, SsgiUniform, SSGI_OUTPUT_FORMAT};
+pub use rt_accel::{RtAccel, BlasMeshData, mat4_to_tlas_transform};
+pub use rt_shadow::{RtShadowResources, RtShadowUniform, RT_SHADOW_FORMAT};