Simplify and modularize code, update envmap info txt

assets/environment_maps/info.txt

@@ -1,6 +1,7 @@
-The pisa_*.ktx2 files were generated from https://github.com/KhronosGroup/glTF-Sample-Environments/blob/master/pisa.hdr using the following tools and commands:
-- IBL environment map prefiltering to cubemaps: https://github.com/KhronosGroup/glTF-IBL-Sampler
-  - Diffuse: ./cli -inputPath pisa.hdr -outCubeMap pisa_diffuse.ktx2 -distribution Lambertian -cubeMapResolution 32
-  - Specular: ./cli -inputPath pisa.hdr -outCubeMap pisa_specular.ktx2 -distribution GGX -cubeMapResolution 512
+The the spiaggia_di_mondello_*.ktx2 files were downloaded from https://polyhaven.com/a/spiaggia_di_mondello distributed under the CC0 license by Andreas Mischok.
+- IBL environment map prefiltering to cubemaps: https://github.com/mate-h/blender-envmap
+  - Imported the GLTF scene into Blender and saved the scene into the blend file
+  - Exported the reflection probe and the environment map as KTX2 files using the command line tool
+  - blender-envmap spiaggia_di_mondello_2k.exr --resolution 512
 - Converting to rgb9e5 format with zstd 'supercompression': https://github.com/DGriffin91/bevy_mod_environment_map_tools
-  - cargo run --release -- --inputs pisa_diffuse.ktx2,pisa_specular.ktx2 --outputs pisa_diffuse_rgb9e5_zstd.ktx2,pisa_specular_rgb9e5_zstd.ktx2
+  - cargo run --release -- --inputs spiaggia_di_mondello_*.ktx2 --outputs spiaggia_di_mondello_*_rgb9e5_zstd.ktx2

crates/bevy_pbr/src/light_probe/environment_filter.wgsl

@@ -1,5 +1,5 @@
 #import bevy_render::maths::{PI, PI_2};
-#import bevy_pbr::lighting::perceptualRoughnessToRoughness;
+#import bevy_pbr::utils::{build_orthonormal_basis};
 
 struct FilteringConstants {
     mip_level: f32,
@@ -92,18 +92,6 @@ fn sample_environment(dir: vec3f, level: f32) -> vec4f {
     return textureSampleLevel(input_texture, input_sampler, cube_uv.uv, cube_uv.face, level);
 }
 
-// Calculate tangent space for the given normal
-fn calculate_tangent_frame(normal: vec3f) -> mat3x3f {
-    // Use a robust method to pick a tangent
-    var up = vec3f(1.0, 0.0, 0.0);
-    if abs(normal.z) < 0.999 {
-        up = vec3f(0.0, 0.0, 1.0);
-    }
-    let tangent = normalize(cross(up, normal));
-    let bitangent = cross(normal, tangent);
-    return mat3x3f(tangent, bitangent, normal);
-}
-
 // Hammersley sequence for quasi-random points
 fn hammersley_2d(i: u32, n: u32) -> vec2f {
     // Van der Corput sequence
@@ -125,7 +113,17 @@ fn sample_noise(pixel_coords: vec2u) -> vec4f {
     return textureSampleLevel(blue_noise_texture, input_sampler, uv, 0.0);
 }
 
+// from bevy_pbr/src/render/pbr_lighting.wgsl
+fn perceptualRoughnessToRoughness(perceptualRoughness: f32) -> f32 {
+    // clamp perceptual roughness to prevent precision problems
+    // According to Filament design 0.089 is recommended for mobile
+    // Filament uses 0.045 for non-mobile
+    let clampedPerceptualRoughness = clamp(perceptualRoughness, 0.089, 1.0);
+    return clampedPerceptualRoughness * clampedPerceptualRoughness;
+}
+
 // GGX/Trowbridge-Reitz normal distribution function (D term)
+// from bevy_pbr/src/render/pbr_lighting.wgsl
 fn D_GGX(roughness: f32, NdotH: f32) -> f32 {
     let oneMinusNdotHSquared = 1.0 - NdotH * NdotH;
     let a = NdotH * roughness;
@@ -136,14 +134,11 @@ fn D_GGX(roughness: f32, NdotH: f32) -> f32 {
 
 // Importance sample GGX normal distribution function for a given roughness
 fn importance_sample_ggx(xi: vec2f, roughness: f32, normal: vec3f) -> vec3f {
-    // Use roughness^2 to ensure correct specular highlights
-    let a = roughness * roughness;
-    
     // Sample in spherical coordinates
     let phi = PI_2 * xi.x;
     
     // GGX mapping from uniform random to GGX distribution
-    let cos_theta = sqrt((1.0 - xi.y) / (1.0 + (a * a - 1.0) * xi.y));
+    let cos_theta = sqrt((1.0 - xi.y) / (1.0 + (roughness * roughness - 1.0) * xi.y));
     let sin_theta = sqrt(1.0 - cos_theta * cos_theta);
     
     // Convert to cartesian
@@ -154,7 +149,7 @@ fn importance_sample_ggx(xi: vec2f, roughness: f32, normal: vec3f) -> vec3f {
     );
     
     // Transform from tangent to world space
-    return calculate_tangent_frame(normal) * h;
+    return build_orthonormal_basis(normal) * h;
 }
 
 // Calculate LOD for environment map lookup using filtered importance sampling
@@ -171,7 +166,7 @@ fn calculate_environment_map_lod(pdf: f32, width: f32, samples: f32) -> f32 {
 
 // Smith geometric shadowing function
 fn G_Smith(NoV: f32, NoL: f32, roughness: f32) -> f32 {
-    let k = (roughness * roughness) / 2.0;
+    let k = roughness / 2.0;
     let GGXL = NoL / (NoL * (1.0 - k) + k);
     let GGXV = NoV / (NoV * (1.0 - k) + k);
     return GGXL * GGXV;
@@ -197,8 +192,9 @@ fn generate_radiance_map(@builtin(global_invocation_id) global_id: vec3u) {
     // For radiance map, view direction = normal for perfect reflection
     let view = normal;
     
-    // Get the roughness parameter
-    let roughness = constants.roughness;
+    // Convert perceptual roughness to physical microfacet roughness
+    let perceptual_roughness = constants.roughness;
+    let roughness = perceptualRoughnessToRoughness(perceptual_roughness);
     
     // Get blue noise offset for stratification
     let vector_noise = sample_noise(coords);
@@ -292,7 +288,7 @@ fn uniform_sample_sphere(i: u32, normal: vec3f) -> vec3f {
         z
     );
 
-    let tangent_frame = calculate_tangent_frame(normal);
+    let tangent_frame = build_orthonormal_basis(normal);
     return normalize(tangent_frame * dir_uniform);
 }
 

crates/bevy_pbr/src/light_probe/generate.rs

@@ -51,9 +51,8 @@ use bevy_render::{
 
 use bevy_light::{EnvironmentMapLight, GeneratedEnvironmentMapLight};
 
-/// Sphere Cosine Weighted Irradiance shader handle
-pub const STBN_SPHERE: Handle<Image> = uuid_handle!("3110b545-78e0-48fc-b86e-8bc0ea50fc67");
-pub const STBN_VEC2: Handle<Image> = uuid_handle!("3110b545-78e0-48fc-b86e-8bc0ea50fc67");
+/// Handle for Spatio-Temporal Blue Noise texture
+pub const SBTN: Handle<Image> = uuid_handle!("3110b545-78e0-48fc-b86e-8bc0ea50fc67");
 
 /// Labels for the environment map generation nodes
 #[derive(PartialEq, Eq, Debug, Copy, Clone, Hash, RenderLabel)]
@@ -506,13 +505,8 @@ pub fn prepare_generator_bind_groups(
     render_images: Res<RenderAssets<GpuImage>>,
     mut commands: Commands,
 ) {
-    // Get blue noise texture
-    let sphere_cosine_weights = render_images
-        .get(&STBN_SPHERE)
-        .expect("Sphere cosine weights texture not loaded");
-
     let vector2_uniform = render_images
-        .get(&STBN_VEC2)
+        .get(&SBTN)
         .expect("Vector2 uniform texture not loaded");
 
     for (entity, textures, env_map_light) in &light_probes {
@@ -644,8 +638,8 @@ pub fn prepare_generator_bind_groups(
             sample_count: 1024,
             roughness: 1.0,
             blue_noise_size: Vec2::new(
-                sphere_cosine_weights.size.width as f32,
-                sphere_cosine_weights.size.height as f32,
+                vector2_uniform.size.width as f32,
+                vector2_uniform.size.height as f32,
             ),
             white_point: env_map_light.white_point,
         };
@@ -671,7 +665,7 @@ pub fn prepare_generator_bind_groups(
                 (1, &samplers.linear),
                 (2, &irradiance_map),
                 (3, &irradiance_constants_buffer),
-                (4, &sphere_cosine_weights.texture_view),
+                (4, &vector2_uniform.texture_view),
             )),
         );
 

crates/bevy_pbr/src/light_probe/mod.rs

@@ -35,18 +35,15 @@ use bevy_render::{
     Extract, ExtractSchedule, Render, RenderApp, RenderSystems,
 };
 use bevy_transform::{components::Transform, prelude::GlobalTransform};
-use generate::{
-    extract_generator_entities, generate_environment_map_light, prepare_generator_bind_groups,
-    prepare_intermediate_textures, GeneratorPipelines, SpdNode, STBN_SPHERE, STBN_VEC2,
-};
 use tracing::error;
 
 use core::{hash::Hash, ops::Deref};
 
 use crate::{
     generate::{
-        GeneratorBindGroupLayouts, GeneratorNode, GeneratorSamplers, IrradianceMapNode,
-        RadianceMapNode,
+        extract_generator_entities, generate_environment_map_light, prepare_generator_bind_groups,
+        prepare_intermediate_textures, GeneratorBindGroupLayouts, GeneratorNode,
+        GeneratorPipelines, GeneratorSamplers, IrradianceMapNode, RadianceMapNode, SpdNode, SBTN,
     },
     light_probe::environment_map::EnvironmentMapIds,
 };
@@ -308,11 +305,8 @@ impl Plugin for LightProbePlugin {
         embedded_asset!(app, "spd.wgsl");
         embedded_asset!(app, "copy_mip0.wgsl");
 
-        load_internal_binary_asset!(
-            app,
-            STBN_SPHERE,
-            "noise/sphere_coshemi_gauss1_0.png",
-            |bytes, _: String| Image::from_buffer(
+        load_internal_binary_asset!(app, SBTN, "sbtn_vec2.png", |bytes, _: String| {
+            Image::from_buffer(
                 bytes,
                 ImageType::Extension("png"),
                 CompressedImageFormats::NONE,
@@ -320,22 +314,8 @@ impl Plugin for LightProbePlugin {
                 ImageSampler::Default,
                 RenderAssetUsages::RENDER_WORLD,
             )
-            .expect("Failed to load sphere cosine weighted blue noise texture")
-        );
-        load_internal_binary_asset!(
-            app,
-            STBN_VEC2,
-            "noise/vector2_uniform_gauss1_0.png",
-            |bytes, _: String| Image::from_buffer(
-                bytes,
-                ImageType::Extension("png"),
-                CompressedImageFormats::NONE,
-                false,
-                ImageSampler::Default,
-                RenderAssetUsages::RENDER_WORLD,
-            )
-            .expect("Failed to load vector2 uniform blue noise texture")
-        );
+            .expect("Failed to load spatio-temporal blue noise texture")
+        });
 
         app.add_plugins(ExtractInstancesPlugin::<EnvironmentMapIds>::new())
             .add_plugins(SyncComponentPlugin::<GeneratedEnvironmentMapLight>::default())

crates/bevy_pbr/src/render/utils.wgsl

@@ -68,6 +68,16 @@ fn octahedral_decode_signed(v: vec2<f32>) -> vec3<f32> {
     return normalize(n);
 }
 
+// https://jcgt.org/published/0006/01/01/paper.pdf
+fn build_orthonormal_basis(normal: vec3<f32>) -> mat3x3<f32> {
+    let sign = select(-1.0, 1.0, normal.z >= 0.0);
+    let a = -1.0 / (sign + normal.z);
+    let b = normal.x * normal.y * a;
+    let tangent = vec3(1.0 + sign * normal.x * normal.x * a, sign * b, -sign * normal.x);
+    let bitangent = vec3(b, sign + normal.y * normal.y * a, -normal.y);
+    return mat3x3(tangent, bitangent, normal);
+}
+
 // https://blog.demofox.org/2022/01/01/interleaved-gradient-noise-a-different-kind-of-low-discrepancy-sequence
 fn interleaved_gradient_noise(pixel_coordinates: vec2<f32>, frame: u32) -> f32 {
     let xy = pixel_coordinates + 5.588238 * f32(frame % 64u);

crates/bevy_solari/src/scene/sampling.wgsl

@@ -1,6 +1,6 @@
 #define_import_path bevy_solari::sampling
 
-#import bevy_pbr::utils::{rand_f, rand_vec2f, rand_range_u}
+#import bevy_pbr::utils::{rand_f, rand_vec2f, rand_range_u, build_orthonormal_basis}
 #import bevy_render::maths::{PI, PI_2}
 #import bevy_solari::scene_bindings::{trace_ray, RAY_T_MIN, RAY_T_MAX, light_sources, directional_lights, LIGHT_SOURCE_KIND_DIRECTIONAL, resolve_triangle_data_full}
 
@@ -187,13 +187,3 @@ fn triangle_barycentrics(random: vec2<f32>) -> vec3<f32> {
     if barycentrics.x + barycentrics.y > 1.0 { barycentrics = 1.0 - barycentrics; }
     return vec3(1.0 - barycentrics.x - barycentrics.y, barycentrics);
 }
-
-// https://jcgt.org/published/0006/01/01/paper.pdf
-fn build_orthonormal_basis(normal: vec3<f32>) -> mat3x3<f32> {
-    let sign = select(-1.0, 1.0, normal.z >= 0.0);
-    let a = -1.0 / (sign + normal.z);
-    let b = normal.x * normal.y * a;
-    let tangent = vec3(1.0 + sign * normal.x * normal.x * a, sign * b, -sign * normal.x);
-    let bitangent = vec3(b, sign + normal.y * normal.y * a, -normal.y);
-    return mat3x3(tangent, bitangent, normal);
-}

examples/3d/reflection_probes.rs

@@ -53,14 +53,17 @@ struct Cubemaps {
     // The blurry diffuse cubemap that reflects the world, but not the cubes.
     diffuse_environment_map: Handle<Image>,
 
-    // The specular cubemap that reflects the world, but not the cubes.
+    // The specular cubemap mip chain that reflects the world, but not the cubes.
     specular_environment_map: Handle<Image>,
 
     // The blurry diffuse cubemap that reflects both the world and the cubes.
     diffuse_reflection_probe: Handle<Image>,
 
-    // The specular cubemap that reflects both the world and the cubes.
+    // The specular cubemap mip chain that reflects both the world and the cubes.
     specular_reflection_probe: Handle<Image>,
+
+    // Environment map with a single mip level
+    environment_map: Handle<Image>,
 }
 
 fn main() {
@@ -164,39 +167,18 @@ fn spawn_reflection_probe(commands: &mut Commands, cubemaps: &Cubemaps) {
         // 2.0 because the sphere's radius is 1.0 and we want to fully enclose it.
         Transform::from_scale(Vec3::splat(2.0)),
     ));
-    // spawn directional light for the sun
-    commands.spawn((
-        DirectionalLight {
-            illuminance: 10_000.0,
-            ..default()
-        },
-        // Roughly match the position of the sun in the environment map
-        Transform::from_xyz(1.0, 0.5, 0.7).looking_at(Vec3::ZERO, Vec3::Y),
-    ));
 }
 
 fn spawn_generated_environment_map(commands: &mut Commands, cubemaps: &Cubemaps) {
     commands.spawn((
         LightProbe,
         GeneratedEnvironmentMapLight {
-            // Reuse the specular map for the generated environment map, even
-            // though it already has mip levels. In reality you would use a
-            // cubemap texture without mip levels and generate the mips using
-            // this component by filtering the cubemap on the GPU.
-            environment_map: cubemaps.specular_environment_map.clone(),
+            environment_map: cubemaps.environment_map.clone(),
             intensity: 5000.0,
             ..default()
         },
         Transform::from_scale(Vec3::splat(2.0)),
     ));
-    // spawn directional light
-    commands.spawn((
-        DirectionalLight {
-            illuminance: 30_000.0,
-            ..default()
-        },
-        Transform::from_xyz(1.0, 0.5, 0.7).looking_at(Vec3::ZERO, Vec3::Y),
-    ));
 }
 
 // Spawns the help text.
@@ -226,10 +208,7 @@ fn add_environment_map_to_camera(
             .entity(camera_entity)
             .insert(create_camera_environment_map_light(&cubemaps))
             .insert(Skybox {
-                // Reuse the specular map for the skybox since it's not too blurry.
-                // In reality you wouldn't do this--you'd use a real skybox texture--but
-                // reusing the textures like this saves space in the Bevy repository.
-                image: cubemaps.specular_environment_map.clone(),
+                image: cubemaps.environment_map.clone(),
                 brightness: 5000.0,
                 ..default()
             });
@@ -384,13 +363,15 @@ impl FromWorld for Cubemaps {
     fn from_world(world: &mut World) -> Self {
         Cubemaps {
             diffuse_environment_map: world
-                .load_asset("environment_maps/spiaggia_di_mondello_2k_probe_diffuse_rgb5e9.ktx2"),
+                .load_asset("environment_maps/spiaggia_di_mondello_probe_diffuse.ktx2"),
             specular_environment_map: world
-                .load_asset("environment_maps/spiaggia_di_mondello_2k_specular_rgb5e9.ktx2"),
+                .load_asset("environment_maps/spiaggia_di_mondello_specular.ktx2"),
             specular_reflection_probe: world
-                .load_asset("environment_maps/spiaggia_di_mondello_2k_probe_specular_rgb5e9.ktx2"),
+                .load_asset("environment_maps/spiaggia_di_mondello_probe_specular.ktx2"),
             diffuse_reflection_probe: world
-                .load_asset("environment_maps/spiaggia_di_mondello_2k_probe_diffuse_rgb5e9.ktx2"),
+                .load_asset("environment_maps/spiaggia_di_mondello_probe_diffuse.ktx2"),
+            environment_map: world
+                .load_asset("environment_maps/spiaggia_di_mondello_environment_map.ktx2"),
         }
     }
 }