From 407d8a31305f9e06c9dd8f15a43b0d35778a0b26 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:04:45 +0200
Subject: [PATCH 01/12] Use one triangle over entire screen to ensure full
 rasterization.

---
 .../shaders/materials/proceduralskybox.wgsl   |  9 ++--
 .../shaders/modules/skybox/common.wgsl        | 23 +++++-----
 .../shaders/modules/skybox/procedural.wgsl    | 43 ++++++++-----------
 .../passes/backend/skybox_gradientskybox.wgsl |  2 +-
 .../backend/skybox_proceduralskybox.wgsl      | 39 ++++++-----------
 .../passes/backend/skybox_projection360.wgsl  |  2 +-
 .../passes/backend/skybox_solid_color.wgsl    |  2 +-
 .../world_mesh_forward/skybox/pipeline.rs     |  2 +-
 8 files changed, 48 insertions(+), 74 deletions(-)

diff --git a/crates/renderide/shaders/materials/proceduralskybox.wgsl b/crates/renderide/shaders/materials/proceduralskybox.wgsl
index b0ed61643..4ae01d066 100644
--- a/crates/renderide/shaders/materials/proceduralskybox.wgsl
+++ b/crates/renderide/shaders/materials/proceduralskybox.wgsl
@@ -29,8 +29,7 @@ struct VertexOutput {
     @location(0) ground_color: vec3<f32>,
     @location(1) sky_color: vec3<f32>,
     @location(2) sun_color: vec3<f32>,
-    @location(3) fragment_ray: vec3<f32>,
-    @location(4) sky_ground_factor: f32,
+    @location(3) ray: vec3<f32>,
 }
 
 @vertex
@@ -55,8 +54,7 @@ fn vs_main(
     out.ground_color = terms.ground_color;
     out.sky_color = terms.sky_color;
     out.sun_color = terms.sun_color;
-    out.fragment_ray = terms.fragment_ray;
-    out.sky_ground_factor = terms.sky_ground_factor;
+    out.ray = terms.ray;
     return out;
 }
 
@@ -67,8 +65,7 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
         in.ground_color,
         in.sky_color,
         in.sun_color,
-        in.fragment_ray,
-        in.sky_ground_factor,
+        in.ray,
     );
     return rg::retain_globals_additive(vec4<f32>(
         ps::visible_fragment_color(psmat::params(), terms),
diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index ab58f95ef..f0490d3e0 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -26,24 +26,21 @@ fn fullscreen_clip_pos(vertex_index: u32) -> vec4<f32> {
     return vec4<f32>(x * 2.0 - 1.0, 1.0 - y * 2.0, 0.0, 1.0);
 }
 
+const FULLSCREEN_COVERING_TRIANGLE = mat3x4<f32>(
+    vec4<f32>(-1.0, -1.0, 0.0, 1.0),
+    vec4<f32>(3.0, -1.0, 0.0, 1.0),
+    vec4<f32>(-1.0, 3.0, 0.0, 1.0)
+);
+
 fn fullscreen_quad_clip_pos(vertex_index: u32) -> vec4<f32> {
-    let i = vertex_index % 6u;
-    if (i == 0u) {
-        return vec4<f32>(-1.0, 1.0, 0.0, 1.0);
-    }
+    let i = vertex_index % 3u;
     if (i == 1u) {
-        return vec4<f32>(1.0, 1.0, 0.0, 1.0);
+        return FULLSCREEN_COVERING_TRIANGLE[1];
     }
     if (i == 2u) {
-        return vec4<f32>(-1.0, -1.0, 0.0, 1.0);
-    }
-    if (i == 3u) {
-        return vec4<f32>(-1.0, -1.0, 0.0, 1.0);
-    }
-    if (i == 4u) {
-        return vec4<f32>(1.0, 1.0, 0.0, 1.0);
+        return FULLSCREEN_COVERING_TRIANGLE[2];
     }
-    return vec4<f32>(1.0, -1.0, 0.0, 1.0);
+    return FULLSCREEN_COVERING_TRIANGLE[0];
 }
 
 fn view_is_orthographic(sky: SkyboxView, view_layer: u32) -> bool {
diff --git a/crates/renderide/shaders/modules/skybox/procedural.wgsl b/crates/renderide/shaders/modules/skybox/procedural.wgsl
index ee88600b5..08ec80604 100644
--- a/crates/renderide/shaders/modules/skybox/procedural.wgsl
+++ b/crates/renderide/shaders/modules/skybox/procedural.wgsl
@@ -17,7 +17,7 @@ const KKM_4PI: f32 = KMIE * 4.0 * PI;
 const KSCALE: f32 = 1.0 / (OUTER_RADIUS - 1.0);
 const KSCALE_DEPTH: f32 = 0.25;
 const KSCALE_OVER_SCALE_DEPTH: f32 = (1.0 / (OUTER_RADIUS - 1.0)) / 0.25;
-const KSAMPLES: f32 = 2.0;
+const KSAMPLES: u32 = 2u;
 const MIE_G: f32 = -0.990;
 const MIE_G2: f32 = 0.9801;
 const SKY_GROUND_THRESHOLD: f32 = 0.02;
@@ -41,8 +41,7 @@ struct ProceduralSkyVisibleTerms {
     ground_color: vec3<f32>,
     sky_color: vec3<f32>,
     sun_color: vec3<f32>,
-    fragment_ray: vec3<f32>,
-    sky_ground_factor: f32,
+    ray: vec3<f32>,
 }
 
 struct ScatteringStep {
@@ -145,22 +144,19 @@ fn evaluate_scattering(
         let start_angle = dot(eye_ray, camera_pos) / height;
         let start_offset = depth_init * scale_factor(start_angle);
 
-        let sample_length = far / KSAMPLES;
+        let sample_length = far / f32(KSAMPLES);
         let scaled_length = sample_length * KSCALE;
         let sample_ray = eye_ray * sample_length;
         var sample_point = camera_pos + sample_ray * 0.5;
 
         var front_color = vec3<f32>(0.0);
-        let s0 = scattering_inscatter_step(
-            sample_point, eye_ray, sun_dir, inv_wavelength, kkr_4pi, start_offset, scaled_length,
-        );
-        front_color = front_color + s0.contribution;
-        sample_point = sample_point + sample_ray;
-
-        let s1 = scattering_inscatter_step(
-            sample_point, eye_ray, sun_dir, inv_wavelength, kkr_4pi, start_offset, scaled_length,
-        );
-        front_color = front_color + s1.contribution;
+        for (var i = 0u; i < KSAMPLES; i++) {
+            let step = scattering_inscatter_step(
+                sample_point, eye_ray, sun_dir, inv_wavelength, kkr_4pi, start_offset, scaled_length,
+            );
+            front_color = front_color + step.contribution;
+            sample_point = sample_point + sample_ray;
+        }
 
         c_in = front_color * (inv_wavelength * kkr_esun);
         c_out = front_color * KKM_ESUN;
@@ -175,7 +171,7 @@ fn evaluate_scattering(
         let camera_offset = depth * camera_scale;
         let temp = light_scale + camera_scale;
 
-        let sample_length = far / KSAMPLES;
+        let sample_length = far / f32(KSAMPLES);
         let scaled_length = sample_length * KSCALE;
         let sample_ray = eye_ray * sample_length;
         let sample_point = camera_pos + sample_ray * 0.5;
@@ -220,34 +216,31 @@ fn visible_vertex_terms(params: ProceduralSkyParams, input_eye_ray: vec3<f32>) -
     let ground_color = params.exposure * (scattering.c_in + params.ground_color * scattering.c_out);
     let sky_color = params.exposure * (scattering.c_in * rayleigh_phase(sun_dir, -eye_ray));
     let sun_color = params.exposure * (scattering.c_out * params.sun_color);
-    let fragment_ray = -eye_ray;
-    let sky_ground_factor = fragment_ray.y / SKY_GROUND_THRESHOLD;
     return ProceduralSkyVisibleTerms(
         ground_color,
         sky_color,
         sun_color,
-        fragment_ray,
-        sky_ground_factor,
+        -eye_ray,
     );
 }
 
 fn visible_fragment_color(params: ProceduralSkyParams, terms: ProceduralSkyVisibleTerms) -> vec3<f32> {
-    let sun_dir = safe_normalize(params.sun_direction, vec3<f32>(0.0, 1.0, 0.0));
-    let fragment_ray = safe_normalize(terms.fragment_ray, vec3<f32>(0.0, -1.0, 0.0));
+    let sky_ground_factor = terms.ray.y / SKY_GROUND_THRESHOLD;
     var color = mix(
         terms.sky_color,
         terms.ground_color,
-        clamp(terms.sky_ground_factor, 0.0, 1.0),
+        clamp(sky_ground_factor, 0.0, 1.0),
     );
 
-    if (!sun_disk_mode_none(params.sun_disk_mode) && terms.sky_ground_factor < 0.0) {
+    if (!sun_disk_mode_none(params.sun_disk_mode) && sky_ground_factor < 0.0) {
+        let sun_dir = safe_normalize(params.sun_direction, vec3<f32>(0.0, 1.0, 0.0));
         let sun_size = clamp(params.sun_size, 1.0e-4, 1.0);
         var mie: f32;
         if (sun_disk_mode_high_quality(params.sun_disk_mode)) {
-            let eye_cos = dot(sun_dir, fragment_ray);
+            let eye_cos = dot(sun_dir, terms.ray);
             mie = mie_phase(eye_cos, eye_cos * eye_cos, sun_size);
         } else {
-            mie = calc_sun_spot(sun_dir, -fragment_ray, sun_size);
+            mie = calc_sun_spot(sun_dir, -terms.ray, sun_size);
         }
         color = color + mie * terms.sun_color;
     }
diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index 403f83cb6..85055de40 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -29,7 +29,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_clip_pos(vertex_index);
+    let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
     out.ndc = vec2<f32>(clip.x, clip.y * view.ndc_y_sign_pad.x);
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 184cf1ab3..565361275 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -7,15 +7,12 @@
 #import renderide::skybox::procedural as ps
 #import renderide::skybox::procedural_material as psmat
 #import renderide::skybox::common as skybox
+
 @group(2) @binding(0) var<uniform> view: skybox::SkyboxView;
 
 struct VertexOutput {
     @builtin(position) clip_pos: vec4<f32>,
-    @location(0) ground_color: vec3<f32>,
-    @location(1) sky_color: vec3<f32>,
-    @location(2) sun_color: vec3<f32>,
-    @location(3) fragment_ray: vec3<f32>,
-    @location(4) sky_ground_factor: f32,
+    @location(0) @interpolate(flat) view_layer: u32,
 }
 
 @vertex
@@ -33,34 +30,24 @@ fn vs_main(
 #else
     let view_layer = 0u;
 #endif
-    let ndc = vec2<f32>(clip.x, clip.y * view.ndc_y_sign_pad.x);
-    let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, view_layer != 0u);
-    let view_ray = skybox::view_ray_from_ndc(
-        ndc,
-        proj_params,
-        skybox::view_is_orthographic(view, view_layer),
-    );
-    let world_ray = skybox::world_ray_from_view_ray(view_ray, view, view_layer);
-    let terms = ps::visible_vertex_terms(psmat::params(), world_ray);
-    out.ground_color = terms.ground_color;
-    out.sky_color = terms.sky_color;
-    out.sun_color = terms.sun_color;
-    out.fragment_ray = terms.fragment_ray;
-    out.sky_ground_factor = terms.sky_ground_factor;
+    out.view_layer = view_layer;
     return out;
 }
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
-    let terms = ps::ProceduralSkyVisibleTerms(
-        in.ground_color,
-        in.sky_color,
-        in.sun_color,
-        in.fragment_ray,
-        in.sky_ground_factor,
+    let ndc = vec2<f32>(in.clip_pos.x, in.clip_pos.y * view.ndc_y_sign_pad.x);
+    let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, in.view_layer != 0u);
+    let view_ray = skybox::view_ray_from_ndc(
+        ndc,
+        proj_params,
+        skybox::view_is_orthographic(view, in.view_layer),
     );
+    let world_ray = skybox::world_ray_from_view_ray(view_ray, view, in.view_layer);
+    let ps_params = psmat::params();
+    let terms = ps::visible_vertex_terms(ps_params, world_ray);
     return rg::retain_globals_additive(vec4<f32>(
-        ps::visible_fragment_color(psmat::params(), terms),
+        ps::visible_fragment_color(ps_params, terms),
         1.0,
     ));
 }
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index ea7d375ab..0571cf0b3 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -102,7 +102,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_clip_pos(vertex_index);
+    let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
     out.ndc = vec2<f32>(clip.x, clip.y * view.ndc_y_sign_pad.x);
diff --git a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
index 024bcd41b..9c72dacb0 100644
--- a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
@@ -11,7 +11,7 @@ struct VertexOutput {
 @vertex
 fn vs_main(@builtin(vertex_index) vertex_index: u32) -> VertexOutput {
     var out: VertexOutput;
-    out.clip_pos = skybox::fullscreen_clip_pos(vertex_index);
+    out.clip_pos = skybox::fullscreen_quad_clip_pos(vertex_index);
     return out;
 }
 
diff --git a/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs b/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs
index 8c0f26ea1..e4cda7ba7 100644
--- a/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs
+++ b/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs
@@ -49,7 +49,7 @@ impl SkyboxFamily {
     pub(super) const fn draw_vertex_count(self) -> u32 {
         match self {
             Self::Projection360 | Self::Gradient => 3,
-            Self::Procedural => 6,
+            Self::Procedural => 3,
         }
     }
 }

From c9fd2c0e51055f28bff233493201fd4d6407e103 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:04:45 +0200
Subject: [PATCH 02/12] Move NDC computation to fragment shader

---
 crates/renderide/shaders/modules/skybox/common.wgsl        | 7 ++++---
 .../shaders/passes/backend/skybox_gradientskybox.wgsl      | 7 +++----
 .../shaders/passes/backend/skybox_projection360.wgsl       | 7 +++----
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index f0490d3e0..a36bf501f 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -57,9 +57,10 @@ fn view_ray_from_ndc(ndc: vec2<f32>, proj_params: vec4<f32>, orthographic: bool)
     }
     // Asymmetric OpenXR projections store skew on the Z column. With sky rays fixed at z = -1
     // and clip_w = -view_z, inverse projection uses ndc + skew.
-    let view_x = (ndc.x + proj_params.z) / max(abs(proj_params.x), 0.000001);
-    let view_y = (ndc.y + proj_params.w) / max(abs(proj_params.y), 0.000001);
-    return normalize(vec3<f32>(view_x, view_y, -1.0));
+    let view_unscaled = vec2<f32>(ndc.x + proj_params.z, ndc.y + proj_params.w);
+    let proj_params_signs = sign(sign(proj_params.xy) * 2.0 + 1.0);
+    let proj_params_safe = proj_params_signs * max(abs(proj_params.xy), vec2<f32>(0.000001));
+    return normalize(vec3<f32>(view_unscaled / proj_params_safe, -1.0));
 }
 
 fn world_ray_from_view_ray(view_ray: vec3<f32>, sky: SkyboxView, view_layer: u32) -> vec3<f32> {
diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index 85055de40..3987608d7 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -18,8 +18,7 @@ struct GradientSkyboxMaterial {
 
 struct VertexOutput {
     @builtin(position) clip_pos: vec4<f32>,
-    @location(0) ndc: vec2<f32>,
-    @location(1) @interpolate(flat) view_layer: u32,
+    @location(0) @interpolate(flat) view_layer: u32,
 }
 
 @vertex
@@ -32,7 +31,6 @@ fn vs_main(
     let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
-    out.ndc = vec2<f32>(clip.x, clip.y * view.ndc_y_sign_pad.x);
 #ifdef MULTIVIEW
     out.view_layer = view_idx;
 #else
@@ -43,9 +41,10 @@ fn vs_main(
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
+    let ndc = vec2<f32>(in.clip_pos.x, in.clip_pos.y * view.ndc_y_sign_pad.x);
     let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, in.view_layer != 0u);
     let view_ray = skybox::view_ray_from_ndc(
-        in.ndc,
+        ndc,
         proj_params,
         skybox::view_is_orthographic(view, in.view_layer),
     );
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index 0571cf0b3..bcef8eacc 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -51,8 +51,7 @@ struct Projection360Material {
 
 struct VertexOutput {
     @builtin(position) clip_pos: vec4<f32>,
-    @location(0) ndc: vec2<f32>,
-    @location(1) @interpolate(flat) view_layer: u32,
+    @location(0) @interpolate(flat) view_layer: u32,
 }
 
 fn projection360_params() -> p360m::Projection360Params {
@@ -105,7 +104,6 @@ fn vs_main(
     let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
-    out.ndc = vec2<f32>(clip.x, clip.y * view.ndc_y_sign_pad.x);
 #ifdef MULTIVIEW
     out.view_layer = view_idx;
 #else
@@ -117,8 +115,9 @@ fn vs_main(
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let params = projection360_params();
+    let ndc = vec2<f32>(in.clip_pos.x, in.clip_pos.y * view.ndc_y_sign_pad.x);
     let view_dir = p360m::apply_offset(
-        base_view_dir(in.ndc, in.view_layer),
+        base_view_dir(ndc, in.view_layer),
         params,
         _OffsetTex,
         _OffsetTex_sampler,

From 7fbe3feedb3d05e2bc28d2271b5e25c752e2ed02 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:04:45 +0200
Subject: [PATCH 03/12] Minor refactor

---
 .../shaders/materials/proceduralskybox.wgsl   |  4 +-
 .../shaders/modules/skybox/common.wgsl        |  3 +-
 .../shaders/modules/skybox/procedural.wgsl    | 57 ++++++++++++-------
 .../backend/skybox_proceduralskybox.wgsl      |  3 +-
 4 files changed, 43 insertions(+), 24 deletions(-)

diff --git a/crates/renderide/shaders/materials/proceduralskybox.wgsl b/crates/renderide/shaders/materials/proceduralskybox.wgsl
index 4ae01d066..e19e5240e 100644
--- a/crates/renderide/shaders/materials/proceduralskybox.wgsl
+++ b/crates/renderide/shaders/materials/proceduralskybox.wgsl
@@ -50,7 +50,9 @@ fn vs_main(
 
     var out: VertexOutput;
     out.clip_pos = vp * world_p;
-    let terms = ps::visible_vertex_terms(psmat::params(), mv::model_vector(d, pos.xyz));
+    let ps_params = psmat::params();
+    let scattering_params = ps::scattering_parameters(ps_params);
+    let terms = ps::visible_vertex_terms(ps_params, scattering_params, mv::model_vector(d, pos.xyz));
     out.ground_color = terms.ground_color;
     out.sky_color = terms.sky_color;
     out.sun_color = terms.sun_color;
diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index a36bf501f..45e0fded3 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -57,7 +57,8 @@ fn view_ray_from_ndc(ndc: vec2<f32>, proj_params: vec4<f32>, orthographic: bool)
     }
     // Asymmetric OpenXR projections store skew on the Z column. With sky rays fixed at z = -1
     // and clip_w = -view_z, inverse projection uses ndc + skew.
-    let view_unscaled = vec2<f32>(ndc.x + proj_params.z, ndc.y + proj_params.w);
+
+    let view_unscaled = ndc.xy + proj_params.zw;
     let proj_params_signs = sign(sign(proj_params.xy) * 2.0 + 1.0);
     let proj_params_safe = proj_params_signs * max(abs(proj_params.xy), vec2<f32>(0.000001));
     return normalize(vec3<f32>(view_unscaled / proj_params_safe, -1.0));
diff --git a/crates/renderide/shaders/modules/skybox/procedural.wgsl b/crates/renderide/shaders/modules/skybox/procedural.wgsl
index 08ec80604..384c927d3 100644
--- a/crates/renderide/shaders/modules/skybox/procedural.wgsl
+++ b/crates/renderide/shaders/modules/skybox/procedural.wgsl
@@ -8,6 +8,7 @@ const INNER_RADIUS: f32 = 1.0;
 const OUTER_RADIUS_SQ: f32 = OUTER_RADIUS * OUTER_RADIUS;
 const INNER_RADIUS_SQ: f32 = INNER_RADIUS * INNER_RADIUS;
 const CAMERA_HEIGHT: f32 = 0.0001;
+const CAMERA_POS_HEIGHT: f32 = INNER_RADIUS +CAMERA_HEIGHT;
 const KMIE: f32 = 0.0010;
 const KSUN_BRIGHTNESS: f32 = 20.0;
 const KMAX_SCATTER: f32 = 50.0;
@@ -44,6 +45,11 @@ struct ProceduralSkyVisibleTerms {
     ray: vec3<f32>,
 }
 
+struct ScatteringParameters {
+    kkr_in: vec3<f32>,
+    kkr_scatter: vec3<f32>,
+}
+
 struct ScatteringStep {
     contribution: vec3<f32>,
     attenuate: vec3<f32>,
@@ -94,8 +100,7 @@ fn scattering_inscatter_step(
     sample_point: vec3<f32>,
     eye_ray: vec3<f32>,
     sun_dir: vec3<f32>,
-    inv_wavelength: vec3<f32>,
-    kkr_4pi: f32,
+    kkr_scatter: vec3<f32>,
     start_offset: f32,
     scaled_length: f32,
 ) -> ScatteringStep {
@@ -104,14 +109,13 @@ fn scattering_inscatter_step(
     let light_angle = dot(sun_dir, sample_point) / h;
     let camera_angle = dot(eye_ray, sample_point) / h;
     let scatter = start_offset + depth * (scale_factor(light_angle) - scale_factor(camera_angle));
-    let attenuate = exp(-clamp(scatter, 0.0, KMAX_SCATTER) * (inv_wavelength * kkr_4pi + KKM_4PI));
+    let attenuate = exp(-clamp(scatter, 0.0, KMAX_SCATTER) * kkr_scatter);
     return ScatteringStep(attenuate * (depth * scaled_length), attenuate);
 }
 
 fn ground_inscatter_step(
     sample_point: vec3<f32>,
-    inv_wavelength: vec3<f32>,
-    kkr_4pi: f32,
+    kkr_scatter: vec3<f32>,
     temp: f32,
     camera_offset: f32,
     scaled_length: f32,
@@ -119,19 +123,16 @@ fn ground_inscatter_step(
     let h = length(sample_point);
     let depth = exp(KSCALE_OVER_SCALE_DEPTH * (INNER_RADIUS - h));
     let scatter = depth * temp - camera_offset;
-    let attenuate = exp(-clamp(scatter, 0.0, KMAX_SCATTER) * (inv_wavelength * kkr_4pi + KKM_4PI));
+    let attenuate = exp(-clamp(scatter, 0.0, KMAX_SCATTER) * kkr_scatter);
     return ScatteringStep(attenuate * (depth * scaled_length), attenuate);
 }
 
 fn evaluate_scattering(
     eye_ray: vec3<f32>,
     sun_dir: vec3<f32>,
-    inv_wavelength: vec3<f32>,
-    krayleigh: f32,
+    scattering_params: ScatteringParameters,
 ) -> ScatteringOutput {
-    let kkr_esun = krayleigh * KSUN_BRIGHTNESS;
-    let kkr_4pi = krayleigh * 4.0 * PI;
-    let camera_pos = vec3<f32>(0.0, INNER_RADIUS + CAMERA_HEIGHT, 0.0);
+    let camera_pos = vec3<f32>(0.0, CAMERA_POS_HEIGHT, 0.0);
 
     var c_in: vec3<f32>;
     var c_out: vec3<f32>;
@@ -139,7 +140,7 @@ fn evaluate_scattering(
     if (eye_ray.y >= 0.0) {
         let far = sqrt(OUTER_RADIUS_SQ + INNER_RADIUS_SQ * eye_ray.y * eye_ray.y - INNER_RADIUS_SQ)
             - INNER_RADIUS * eye_ray.y;
-        let height = INNER_RADIUS + CAMERA_HEIGHT;
+        let height = CAMERA_POS_HEIGHT;
         let depth_init = exp(KSCALE_OVER_SCALE_DEPTH * (-CAMERA_HEIGHT));
         let start_angle = dot(eye_ray, camera_pos) / height;
         let start_offset = depth_init * scale_factor(start_angle);
@@ -152,13 +153,13 @@ fn evaluate_scattering(
         var front_color = vec3<f32>(0.0);
         for (var i = 0u; i < KSAMPLES; i++) {
             let step = scattering_inscatter_step(
-                sample_point, eye_ray, sun_dir, inv_wavelength, kkr_4pi, start_offset, scaled_length,
+                sample_point, eye_ray, sun_dir, scattering_params.kkr_scatter, start_offset, scaled_length,
             );
             front_color = front_color + step.contribution;
             sample_point = sample_point + sample_ray;
         }
 
-        c_in = front_color * (inv_wavelength * kkr_esun);
+        c_in = front_color * (scattering_params.kkr_in);
         c_out = front_color * KKM_ESUN;
     } else {
         let far = (-CAMERA_HEIGHT) / min(-0.001, eye_ray.y);
@@ -177,11 +178,11 @@ fn evaluate_scattering(
         let sample_point = camera_pos + sample_ray * 0.5;
 
         let g = ground_inscatter_step(
-            sample_point, inv_wavelength, kkr_4pi, temp, camera_offset, scaled_length,
+            sample_point, scattering_params.kkr_scatter, temp, camera_offset, scaled_length,
         );
         let front_color = g.contribution;
 
-        c_in = front_color * (inv_wavelength * kkr_esun + KKM_ESUN);
+        c_in = front_color * (scattering_params.kkr_in + KKM_ESUN);
         c_out = clamp(g.attenuate, vec3<f32>(0.0), vec3<f32>(1.0));
     }
 
@@ -205,13 +206,25 @@ fn sun_disk_mode_high_quality(mode: f32) -> bool {
     return mode > 1.5;
 }
 
-fn visible_vertex_terms(params: ProceduralSkyParams, input_eye_ray: vec3<f32>) -> ProceduralSkyVisibleTerms {
-    let eye_ray = safe_normalize(input_eye_ray, vec3<f32>(0.0, 1.0, 0.0));
-    let sun_dir = safe_normalize(params.sun_direction, vec3<f32>(0.0, 1.0, 0.0));
+fn scattering_parameters(params: ProceduralSkyParams) -> ScatteringParameters {
     let scattering_wavelength = scattering_wavelength_from_tint(params.sky_tint);
     let inv_wavelength = 1.0 / pow(scattering_wavelength, vec3<f32>(4.0));
     let krayleigh = mix(0.0, 0.0025, pow(max(params.atmosphere_thickness, 0.0), 2.5));
-    let scattering = evaluate_scattering(eye_ray, sun_dir, inv_wavelength, krayleigh);
+    let kkr_esun = krayleigh * KSUN_BRIGHTNESS;
+    let kkr_4pi = krayleigh * 4.0 * PI;
+    let kkr_in = inv_wavelength * kkr_esun;
+    let kkr_scatter = inv_wavelength * kkr_4pi + KKM_4PI;
+    return ScatteringParameters(kkr_in, kkr_scatter);
+}
+
+fn visible_vertex_terms(
+    params: ProceduralSkyParams,
+    scattering_params: ScatteringParameters,
+    input_eye_ray: vec3<f32>
+) -> ProceduralSkyVisibleTerms {
+    let eye_ray = safe_normalize(input_eye_ray, vec3<f32>(0.0, 1.0, 0.0));
+    let sun_dir = safe_normalize(params.sun_direction, vec3<f32>(0.0, 1.0, 0.0));
+    let scattering = evaluate_scattering(eye_ray, sun_dir, scattering_params);
 
     let ground_color = params.exposure * (scattering.c_in + params.ground_color * scattering.c_out);
     let sky_color = params.exposure * (scattering.c_in * rayleigh_phase(sun_dir, -eye_ray));
@@ -249,5 +262,7 @@ fn visible_fragment_color(params: ProceduralSkyParams, terms: ProceduralSkyVisib
 }
 
 fn sample(params: ProceduralSkyParams, input_eye_ray: vec3<f32>) -> vec3<f32> {
-    return visible_fragment_color(params, visible_vertex_terms(params, input_eye_ray));
+    let scattering_params = scattering_parameters(params);
+    let vertex_terms = visible_vertex_terms(params, scattering_params, input_eye_ray);
+    return visible_fragment_color(params, vertex_terms);
 }
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 565361275..5cf5ec973 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -45,7 +45,8 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     );
     let world_ray = skybox::world_ray_from_view_ray(view_ray, view, in.view_layer);
     let ps_params = psmat::params();
-    let terms = ps::visible_vertex_terms(ps_params, world_ray);
+    let scattering_params = ps::scattering_parameters(ps_params);
+    let terms = ps::visible_vertex_terms(ps_params, scattering_params, world_ray);
     return rg::retain_globals_additive(vec4<f32>(
         ps::visible_fragment_color(ps_params, terms),
         1.0,

From fc1e295bdc439389fa7b767abf17b2ebbb289237 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:04:45 +0200
Subject: [PATCH 04/12] Use same fullscreen vertex generation as overlays

---
 .../shaders/modules/skybox/common.wgsl        | 23 -------------------
 .../passes/backend/skybox_gradientskybox.wgsl |  3 ++-
 .../backend/skybox_proceduralskybox.wgsl      |  3 ++-
 .../passes/backend/skybox_projection360.wgsl  |  3 ++-
 .../passes/backend/skybox_solid_color.wgsl    |  3 ++-
 5 files changed, 8 insertions(+), 27 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index 45e0fded3..53ff3c42e 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -20,29 +20,6 @@ struct SkyboxView {
     ndc_y_sign_pad: vec4<f32>,
 }
 
-fn fullscreen_clip_pos(vertex_index: u32) -> vec4<f32> {
-    let x = f32((vertex_index << 1u) & 2u);
-    let y = f32(vertex_index & 2u);
-    return vec4<f32>(x * 2.0 - 1.0, 1.0 - y * 2.0, 0.0, 1.0);
-}
-
-const FULLSCREEN_COVERING_TRIANGLE = mat3x4<f32>(
-    vec4<f32>(-1.0, -1.0, 0.0, 1.0),
-    vec4<f32>(3.0, -1.0, 0.0, 1.0),
-    vec4<f32>(-1.0, 3.0, 0.0, 1.0)
-);
-
-fn fullscreen_quad_clip_pos(vertex_index: u32) -> vec4<f32> {
-    let i = vertex_index % 3u;
-    if (i == 1u) {
-        return FULLSCREEN_COVERING_TRIANGLE[1];
-    }
-    if (i == 2u) {
-        return FULLSCREEN_COVERING_TRIANGLE[2];
-    }
-    return FULLSCREEN_COVERING_TRIANGLE[0];
-}
-
 fn view_is_orthographic(sky: SkyboxView, view_layer: u32) -> bool {
     if (view_layer == 0u) {
         return sky.ndc_y_sign_pad.y > 0.5;
diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index 3987608d7..f15843e5b 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -1,6 +1,7 @@
 //! Fullscreen GradientSkybox sky draw.
 
 #import renderide::frame::globals as rg
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 #import renderide::skybox::gradient as skygrad
 
@@ -28,7 +29,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
+    let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 5cf5ec973..b8e4f0ce1 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -4,6 +4,7 @@
 //! shader-specific keyword decoding for both this pass-side sky draw and the material root.
 
 #import renderide::frame::globals as rg
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::procedural as ps
 #import renderide::skybox::procedural_material as psmat
 #import renderide::skybox::common as skybox
@@ -22,7 +23,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
+    let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index bcef8eacc..2ce7a4883 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -4,6 +4,7 @@
 //! sampling for both this pass-side sky draw and the material root.
 
 #import renderide::frame::globals as rg
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 #import renderide::skybox::projection360 as p360
 #import renderide::skybox::projection360_material as p360m
@@ -101,7 +102,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_quad_clip_pos(vertex_index);
+    let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
diff --git a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
index 9c72dacb0..990900144 100644
--- a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
@@ -1,6 +1,7 @@
 //! Fullscreen solid background for host `CameraClearMode::Color`.
 
 #import renderide::skybox::common as skybox
+#import renderide::core::fullscreen as fs
 
 @group(0) @binding(0) var<uniform> view: skybox::SkyboxView;
 
@@ -11,7 +12,7 @@ struct VertexOutput {
 @vertex
 fn vs_main(@builtin(vertex_index) vertex_index: u32) -> VertexOutput {
     var out: VertexOutput;
-    out.clip_pos = skybox::fullscreen_quad_clip_pos(vertex_index);
+    out.clip_pos = fs::fullscreen_clip_pos(vertex_index);
     return out;
 }
 

From 91fef4ed5462ff5d6dc65fb90537570754824081 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:04:45 +0200
Subject: [PATCH 05/12] Refactor skybox view matrices

---
 .../shaders/modules/skybox/common.wgsl        | 43 ++++++++-----------
 .../passes/backend/skybox_gradientskybox.wgsl |  5 +--
 .../backend/skybox_proceduralskybox.wgsl      |  5 +--
 .../passes/backend/skybox_projection360.wgsl  | 13 +++---
 .../passes/backend/skybox_solid_color.wgsl    |  3 +-
 .../src/passes/world_mesh_forward/skybox.rs   | 36 +++-------------
 6 files changed, 36 insertions(+), 69 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index 53ff3c42e..d19aa9cf0 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -3,12 +3,8 @@
 #define_import_path renderide::skybox::common
 
 struct SkyboxView {
-    view_x_left: vec4<f32>,
-    view_y_left: vec4<f32>,
-    view_z_left: vec4<f32>,
-    view_x_right: vec4<f32>,
-    view_y_right: vec4<f32>,
-    view_z_right: vec4<f32>,
+    view_left: mat4x4<f32>,
+    view_right: mat4x4<f32>,
     clear_color: vec4<f32>,
     /// `.x`: ndc Y sign passed to the fragment shader (1.0 normal, -1.0 for offscreen-RT views).
     /// Offscreen-RT views pre-multiply a clip-space Y flip into the world view-projection so the
@@ -20,6 +16,19 @@ struct SkyboxView {
     ndc_y_sign_pad: vec4<f32>,
 }
 
+fn select_view_proj(view: SkyboxView, view_idx: u32) -> mat4x4<f32> {
+    if (view_idx == 0u) {
+        return view.view_left;
+    }
+    return view.view_right;
+}
+
+fn fullscreen_clip_pos(vertex_index: u32) -> vec4<f32> {
+    let x = f32(vertex_index % 3u);
+    let y = f32(vertex_index % 2u);
+    return vec4<f32>(3.0 * (x - 1.0), y * 4.0 - 1.0, 0.0, 1.0);
+}
+
 fn view_is_orthographic(sky: SkyboxView, view_layer: u32) -> bool {
     if (view_layer == 0u) {
         return sky.ndc_y_sign_pad.y > 0.5;
@@ -30,28 +39,14 @@ fn view_is_orthographic(sky: SkyboxView, view_layer: u32) -> bool {
 /// Reconstructs a view-space sky ray from NDC and packed projection coefficients.
 fn view_ray_from_ndc(ndc: vec2<f32>, proj_params: vec4<f32>, orthographic: bool) -> vec3<f32> {
     if (orthographic) {
-        return vec3<f32>(0.0, 0.0, -1.0);
+        return vec3<f32>(0.0, 0.0, 1.0);
     }
     // Asymmetric OpenXR projections store skew on the Z column. With sky rays fixed at z = -1
     // and clip_w = -view_z, inverse projection uses ndc + skew.
-
-    let view_unscaled = ndc.xy + proj_params.zw;
-    let proj_params_signs = sign(sign(proj_params.xy) * 2.0 + 1.0);
-    let proj_params_safe = proj_params_signs * max(abs(proj_params.xy), vec2<f32>(0.000001));
-    return normalize(vec3<f32>(view_unscaled / proj_params_safe, -1.0));
+    return vec3<f32>((ndc.xy + proj_params.zw) / max(abs(proj_params.xy), vec2<f32>(0.000001)), 1.0);
 }
 
 fn world_ray_from_view_ray(view_ray: vec3<f32>, sky: SkyboxView, view_layer: u32) -> vec3<f32> {
-    if (view_layer == 0u) {
-        return normalize(
-            view_ray.x * sky.view_x_left.xyz +
-            view_ray.y * sky.view_y_left.xyz +
-            view_ray.z * sky.view_z_left.xyz
-        );
-    }
-    return normalize(
-        view_ray.x * sky.view_x_right.xyz +
-        view_ray.y * sky.view_y_right.xyz +
-        view_ray.z * sky.view_z_right.xyz
-    );
+    let view_matrix = select_view_proj(sky, view_layer);
+    return normalize(view_matrix * vec4<f32>(view_ray, 1.0)).xyz;
 }
diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index f15843e5b..7ab220231 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -1,7 +1,6 @@
 //! Fullscreen GradientSkybox sky draw.
 
 #import renderide::frame::globals as rg
-#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 #import renderide::skybox::gradient as skygrad
 
@@ -29,7 +28,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = fs::fullscreen_clip_pos(vertex_index);
+    let clip = skybox::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
@@ -42,7 +41,7 @@ fn vs_main(
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
-    let ndc = vec2<f32>(in.clip_pos.x, in.clip_pos.y * view.ndc_y_sign_pad.x);
+    let ndc = in.clip_pos.xy * vec2<f32>(1.0, view.ndc_y_sign_pad.x);
     let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, in.view_layer != 0u);
     let view_ray = skybox::view_ray_from_ndc(
         ndc,
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index b8e4f0ce1..74ae7acd5 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -4,7 +4,6 @@
 //! shader-specific keyword decoding for both this pass-side sky draw and the material root.
 
 #import renderide::frame::globals as rg
-#import renderide::core::fullscreen as fs
 #import renderide::skybox::procedural as ps
 #import renderide::skybox::procedural_material as psmat
 #import renderide::skybox::common as skybox
@@ -23,7 +22,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = fs::fullscreen_clip_pos(vertex_index);
+    let clip = skybox::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
@@ -37,7 +36,7 @@ fn vs_main(
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
-    let ndc = vec2<f32>(in.clip_pos.x, in.clip_pos.y * view.ndc_y_sign_pad.x);
+    let ndc = in.clip_pos.xy * vec2<f32>(1.0, view.ndc_y_sign_pad.x);
     let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, in.view_layer != 0u);
     let view_ray = skybox::view_ray_from_ndc(
         ndc,
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index 2ce7a4883..67f0cce56 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -4,7 +4,6 @@
 //! sampling for both this pass-side sky draw and the material root.
 
 #import renderide::frame::globals as rg
-#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 #import renderide::skybox::projection360 as p360
 #import renderide::skybox::projection360_material as p360m
@@ -81,6 +80,10 @@ fn projection360_params() -> p360m::Projection360Params {
 }
 
 fn base_view_dir(ndc: vec2<f32>, view_layer: u32) -> vec3<f32> {
+    if (p360m::kw_PERSPECTIVE(mat._RenderideVariantBits)) {
+        return p360::perspective_view_dir_from_ndc(ndc.xy, mat._PerspectiveFOV);
+    }
+
     let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, view_layer != 0u);
     let camera_ray_view = skybox::view_ray_from_ndc(
         ndc,
@@ -88,10 +91,6 @@ fn base_view_dir(ndc: vec2<f32>, view_layer: u32) -> vec3<f32> {
         skybox::view_is_orthographic(view, view_layer),
     );
     let camera_ray_world = skybox::world_ray_from_view_ray(camera_ray_view, view, view_layer);
-
-    if (p360m::kw_PERSPECTIVE(mat._RenderideVariantBits)) {
-        return p360::perspective_view_dir_from_ndc(ndc, mat._PerspectiveFOV);
-    }
     return normalize(-camera_ray_world);
 }
 
@@ -102,7 +101,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = fs::fullscreen_clip_pos(vertex_index);
+    let clip = skybox::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
@@ -116,7 +115,7 @@ fn vs_main(
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let params = projection360_params();
-    let ndc = vec2<f32>(in.clip_pos.x, in.clip_pos.y * view.ndc_y_sign_pad.x);
+    let ndc = in.clip_pos.xy * vec2<f32>(1.0, view.ndc_y_sign_pad.x);
     let view_dir = p360m::apply_offset(
         base_view_dir(ndc, in.view_layer),
         params,
diff --git a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
index 990900144..024bcd41b 100644
--- a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
@@ -1,7 +1,6 @@
 //! Fullscreen solid background for host `CameraClearMode::Color`.
 
 #import renderide::skybox::common as skybox
-#import renderide::core::fullscreen as fs
 
 @group(0) @binding(0) var<uniform> view: skybox::SkyboxView;
 
@@ -12,7 +11,7 @@ struct VertexOutput {
 @vertex
 fn vs_main(@builtin(vertex_index) vertex_index: u32) -> VertexOutput {
     var out: VertexOutput;
-    out.clip_pos = fs::fullscreen_clip_pos(vertex_index);
+    out.clip_pos = skybox::fullscreen_clip_pos(vertex_index);
     return out;
 }
 
diff --git a/crates/renderide/src/passes/world_mesh_forward/skybox.rs b/crates/renderide/src/passes/world_mesh_forward/skybox.rs
index 3956e925f..3fa28524d 100644
--- a/crates/renderide/src/passes/world_mesh_forward/skybox.rs
+++ b/crates/renderide/src/passes/world_mesh_forward/skybox.rs
@@ -42,18 +42,10 @@ struct SkyboxViewBinding {
 #[repr(C)]
 #[derive(Clone, Copy, Debug, Pod, Zeroable)]
 struct SkyboxViewUniforms {
-    /// View-to-world X basis for the left eye or mono view.
-    view_x_left: [f32; 4],
-    /// View-to-world Y basis for the left eye or mono view.
-    view_y_left: [f32; 4],
-    /// View-to-world Z basis for the left eye or mono view.
-    view_z_left: [f32; 4],
-    /// View-to-world X basis for the right eye.
-    view_x_right: [f32; 4],
-    /// View-to-world Y basis for the right eye.
-    view_y_right: [f32; 4],
-    /// View-to-world Z basis for the right eye.
-    view_z_right: [f32; 4],
+    /// View-to-world basis for the left eye or mono view.
+    view_left: [f32; 16],
+    /// View-to-world basis for the right eye.
+    view_right: [f32; 16],
     /// Background color for `CameraClearMode::Color`.
     clear_color: [f32; 4],
     /// `.x`: ndc Y sign passed to the fragment shader (1.0 normal, -1.0 for offscreen-RT views).
@@ -70,8 +62,6 @@ impl SkyboxViewUniforms {
     /// Builds view bases and clear color for the current view.
     fn from_frame(frame: &GraphPassFrame<'_>) -> Self {
         let (left, right) = skybox_world_to_view_pair(frame);
-        let (lx, ly, lz) = view_to_world_basis(left);
-        let (rx, ry, rz) = view_to_world_basis(right);
         let ndc_y_sign = if frame.view.offscreen_write_render_texture_asset_id.is_some() {
             -1.0
         } else {
@@ -79,12 +69,8 @@ impl SkyboxViewUniforms {
         };
         let ortho_flag = projection_kind_orthographic_flag(frame.view.host_camera.projection_kind);
         Self {
-            view_x_left: lx,
-            view_y_left: ly,
-            view_z_left: lz,
-            view_x_right: rx,
-            view_y_right: ry,
-            view_z_right: rz,
+            view_left: left.inverse().to_cols_array(),
+            view_right: right.inverse().to_cols_array(),
             clear_color: frame.view.clear.color.to_array(),
             ndc_y_sign_pad: [ndc_y_sign, ortho_flag, ortho_flag, 0.0],
         }
@@ -427,16 +413,6 @@ fn skybox_world_to_view_pair(frame: &GraphPassFrame<'_>) -> (glam::Mat4, glam::M
     world_to_view_pair_for_skybox(frame.shared.scene, &frame.view.host_camera)
 }
 
-/// Converts a world-to-view matrix into packed view-to-world basis vectors.
-fn view_to_world_basis(world_to_view: glam::Mat4) -> ([f32; 4], [f32; 4], [f32; 4]) {
-    let view_to_world = world_to_view.inverse();
-    (
-        view_to_world.x_axis.truncate().extend(0.0).to_array(),
-        view_to_world.y_axis.truncate().extend(0.0).to_array(),
-        view_to_world.z_axis.truncate().extend(0.0).to_array(),
-    )
-}
-
 fn projection_kind_orthographic_flag(kind: CameraProjectionKind) -> f32 {
     if kind == CameraProjectionKind::Orthographic {
         1.0

From 980d5d81a561d572f0c64af1dd473a9099eed697 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:04:45 +0200
Subject: [PATCH 06/12] Convert from clip to ndc using viewport coordinates

---
 .../renderide/shaders/modules/skybox/common.wgsl  | 15 ++++++++++++---
 .../passes/backend/skybox_gradientskybox.wgsl     |  2 +-
 .../passes/backend/skybox_proceduralskybox.wgsl   |  2 +-
 .../passes/backend/skybox_projection360.wgsl      |  2 +-
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index d19aa9cf0..be880a25d 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -2,6 +2,8 @@
 
 #define_import_path renderide::skybox::common
 
+#import renderide::frame::globals as rg
+
 struct SkyboxView {
     view_left: mat4x4<f32>,
     view_right: mat4x4<f32>,
@@ -29,6 +31,13 @@ fn fullscreen_clip_pos(vertex_index: u32) -> vec4<f32> {
     return vec4<f32>(3.0 * (x - 1.0), y * 4.0 - 1.0, 0.0, 1.0);
 }
 
+fn ndc_from_clip(clip_pos: vec4<f32>) -> vec2<f32> {
+    return vec2<f32>(
+        clip_pos.x / f32(rg::frame.viewport_width),
+        1 - clip_pos.y / f32(rg::frame.viewport_height),
+    ) * 2.0 - 1.0;
+}
+
 fn view_is_orthographic(sky: SkyboxView, view_layer: u32) -> bool {
     if (view_layer == 0u) {
         return sky.ndc_y_sign_pad.y > 0.5;
@@ -39,14 +48,14 @@ fn view_is_orthographic(sky: SkyboxView, view_layer: u32) -> bool {
 /// Reconstructs a view-space sky ray from NDC and packed projection coefficients.
 fn view_ray_from_ndc(ndc: vec2<f32>, proj_params: vec4<f32>, orthographic: bool) -> vec3<f32> {
     if (orthographic) {
-        return vec3<f32>(0.0, 0.0, 1.0);
+        return vec3<f32>(0.0, 0.0, -1.0);
     }
     // Asymmetric OpenXR projections store skew on the Z column. With sky rays fixed at z = -1
     // and clip_w = -view_z, inverse projection uses ndc + skew.
-    return vec3<f32>((ndc.xy + proj_params.zw) / max(abs(proj_params.xy), vec2<f32>(0.000001)), 1.0);
+    return vec3<f32>((ndc.xy + proj_params.zw) / max(abs(proj_params.xy), vec2<f32>(0.000001)), -1.0);
 }
 
 fn world_ray_from_view_ray(view_ray: vec3<f32>, sky: SkyboxView, view_layer: u32) -> vec3<f32> {
     let view_matrix = select_view_proj(sky, view_layer);
-    return normalize(view_matrix * vec4<f32>(view_ray, 1.0)).xyz;
+    return normalize(view_matrix * vec4<f32>(view_ray, 0.0)).xyz;
 }
diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index 7ab220231..9b6d2139c 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -41,7 +41,7 @@ fn vs_main(
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
-    let ndc = in.clip_pos.xy * vec2<f32>(1.0, view.ndc_y_sign_pad.x);
+    let ndc = skybox::ndc_from_clip(in.clip_pos);
     let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, in.view_layer != 0u);
     let view_ray = skybox::view_ray_from_ndc(
         ndc,
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 74ae7acd5..6a2a2043a 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -36,7 +36,7 @@ fn vs_main(
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
-    let ndc = in.clip_pos.xy * vec2<f32>(1.0, view.ndc_y_sign_pad.x);
+    let ndc = skybox::ndc_from_clip(in.clip_pos);
     let proj_params = select(rg::frame.proj_params_left, rg::frame.proj_params_right, in.view_layer != 0u);
     let view_ray = skybox::view_ray_from_ndc(
         ndc,
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index 67f0cce56..19f4ea7d2 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -115,7 +115,7 @@ fn vs_main(
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let params = projection360_params();
-    let ndc = in.clip_pos.xy * vec2<f32>(1.0, view.ndc_y_sign_pad.x);
+    let ndc = skybox::ndc_from_clip(in.clip_pos);
     let view_dir = p360m::apply_offset(
         base_view_dir(ndc, in.view_layer),
         params,

From 3af9f680ac92625407667c075ba0cf6cbbfd2fb4 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 20:47:52 +0200
Subject: [PATCH 07/12] Use common fullscreen_clip_pos

---
 crates/renderide/shaders/modules/skybox/common.wgsl         | 6 ------
 .../shaders/passes/backend/skybox_gradientskybox.wgsl       | 3 ++-
 .../shaders/passes/backend/skybox_proceduralskybox.wgsl     | 3 ++-
 .../shaders/passes/backend/skybox_projection360.wgsl        | 3 ++-
 .../shaders/passes/backend/skybox_solid_color.wgsl          | 3 ++-
 5 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index be880a25d..74d931e15 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -25,12 +25,6 @@ fn select_view_proj(view: SkyboxView, view_idx: u32) -> mat4x4<f32> {
     return view.view_right;
 }
 
-fn fullscreen_clip_pos(vertex_index: u32) -> vec4<f32> {
-    let x = f32(vertex_index % 3u);
-    let y = f32(vertex_index % 2u);
-    return vec4<f32>(3.0 * (x - 1.0), y * 4.0 - 1.0, 0.0, 1.0);
-}
-
 fn ndc_from_clip(clip_pos: vec4<f32>) -> vec2<f32> {
     return vec2<f32>(
         clip_pos.x / f32(rg::frame.viewport_width),
diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index 9b6d2139c..bcfb2fb7e 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -1,6 +1,7 @@
 //! Fullscreen GradientSkybox sky draw.
 
 #import renderide::frame::globals as rg
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 #import renderide::skybox::gradient as skygrad
 
@@ -28,7 +29,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_clip_pos(vertex_index);
+    let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 6a2a2043a..53003e819 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -4,6 +4,7 @@
 //! shader-specific keyword decoding for both this pass-side sky draw and the material root.
 
 #import renderide::frame::globals as rg
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::procedural as ps
 #import renderide::skybox::procedural_material as psmat
 #import renderide::skybox::common as skybox
@@ -22,7 +23,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_clip_pos(vertex_index);
+    let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index 19f4ea7d2..8fc14c60c 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -4,6 +4,7 @@
 //! sampling for both this pass-side sky draw and the material root.
 
 #import renderide::frame::globals as rg
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 #import renderide::skybox::projection360 as p360
 #import renderide::skybox::projection360_material as p360m
@@ -101,7 +102,7 @@ fn vs_main(
     @builtin(view_index) view_idx: u32,
 #endif
 ) -> VertexOutput {
-    let clip = skybox::fullscreen_clip_pos(vertex_index);
+    let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
     out.clip_pos = clip;
 #ifdef MULTIVIEW
diff --git a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
index 024bcd41b..e4398bed5 100644
--- a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
@@ -1,5 +1,6 @@
 //! Fullscreen solid background for host `CameraClearMode::Color`.
 
+#import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
 
 @group(0) @binding(0) var<uniform> view: skybox::SkyboxView;
@@ -11,7 +12,7 @@ struct VertexOutput {
 @vertex
 fn vs_main(@builtin(vertex_index) vertex_index: u32) -> VertexOutput {
     var out: VertexOutput;
-    out.clip_pos = skybox::fullscreen_clip_pos(vertex_index);
+    out.clip_pos = fs::fullscreen_clip_pos(vertex_index);
     return out;
 }
 

From e9eeb70490188253a0e3d94ddb14bc2c2faa1f16 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 21:37:16 +0200
Subject: [PATCH 08/12] Disable scattering with zero atmosphere

Mitigates issue with ring of light in local home
---
 crates/renderide/shaders/modules/skybox/procedural.wgsl | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/crates/renderide/shaders/modules/skybox/procedural.wgsl b/crates/renderide/shaders/modules/skybox/procedural.wgsl
index 384c927d3..76d6f5d8e 100644
--- a/crates/renderide/shaders/modules/skybox/procedural.wgsl
+++ b/crates/renderide/shaders/modules/skybox/procedural.wgsl
@@ -137,7 +137,10 @@ fn evaluate_scattering(
     var c_in: vec3<f32>;
     var c_out: vec3<f32>;
 
-    if (eye_ray.y >= 0.0) {
+    if (length(scattering_params.kkr_in) == 0) {
+        c_in = vec3<f32>(0.0);
+        c_out = vec3<f32>(0.0);
+    } else if (eye_ray.y >= 0.0) {
         let far = sqrt(OUTER_RADIUS_SQ + INNER_RADIUS_SQ * eye_ray.y * eye_ray.y - INNER_RADIUS_SQ)
             - INNER_RADIUS * eye_ray.y;
         let height = CAMERA_POS_HEIGHT;

From c96b6ef8bd4c1d708eab0fd9320f97f57b96a050 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 23:19:38 +0200
Subject: [PATCH 09/12] Less constraining fix for the Local Home skyline

---
 .../renderide/shaders/modules/skybox/procedural.wgsl  | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/procedural.wgsl b/crates/renderide/shaders/modules/skybox/procedural.wgsl
index 76d6f5d8e..a038af053 100644
--- a/crates/renderide/shaders/modules/skybox/procedural.wgsl
+++ b/crates/renderide/shaders/modules/skybox/procedural.wgsl
@@ -130,6 +130,7 @@ fn ground_inscatter_step(
 fn evaluate_scattering(
     eye_ray: vec3<f32>,
     sun_dir: vec3<f32>,
+    params: ProceduralSkyParams,
     scattering_params: ScatteringParameters,
 ) -> ScatteringOutput {
     let camera_pos = vec3<f32>(0.0, CAMERA_POS_HEIGHT, 0.0);
@@ -137,10 +138,7 @@ fn evaluate_scattering(
     var c_in: vec3<f32>;
     var c_out: vec3<f32>;
 
-    if (length(scattering_params.kkr_in) == 0) {
-        c_in = vec3<f32>(0.0);
-        c_out = vec3<f32>(0.0);
-    } else if (eye_ray.y >= 0.0) {
+    if (eye_ray.y >= 0.0) {
         let far = sqrt(OUTER_RADIUS_SQ + INNER_RADIUS_SQ * eye_ray.y * eye_ray.y - INNER_RADIUS_SQ)
             - INNER_RADIUS * eye_ray.y;
         let height = CAMERA_POS_HEIGHT;
@@ -185,7 +183,8 @@ fn evaluate_scattering(
         );
         let front_color = g.contribution;
 
-        c_in = front_color * (scattering_params.kkr_in + KKM_ESUN);
+        let sun_contrib = select(KKM_ESUN, 0, sun_disk_mode_none(params.sun_disk_mode));
+        c_in = front_color * (scattering_params.kkr_in + sun_contrib);
         c_out = clamp(g.attenuate, vec3<f32>(0.0), vec3<f32>(1.0));
     }
 
@@ -227,7 +226,7 @@ fn visible_vertex_terms(
 ) -> ProceduralSkyVisibleTerms {
     let eye_ray = safe_normalize(input_eye_ray, vec3<f32>(0.0, 1.0, 0.0));
     let sun_dir = safe_normalize(params.sun_direction, vec3<f32>(0.0, 1.0, 0.0));
-    let scattering = evaluate_scattering(eye_ray, sun_dir, scattering_params);
+    let scattering = evaluate_scattering(eye_ray, sun_dir, params, scattering_params);
 
     let ground_color = params.exposure * (scattering.c_in + params.ground_color * scattering.c_out);
     let sky_color = params.exposure * (scattering.c_in * rayleigh_phase(sun_dir, -eye_ray));

From ce13d0cd7b439601eaa05742da457ec440c3a08d Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Wed, 20 May 2026 23:30:54 +0200
Subject: [PATCH 10/12] Fix test expectations

---
 crates/renderide/src/camera/projection.rs                 | 3 +--
 crates/renderide/src/passes/world_mesh_forward/skybox.rs  | 3 +--
 .../src/passes/world_mesh_forward/skybox/pipeline.rs      | 8 +++-----
 3 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/crates/renderide/src/camera/projection.rs b/crates/renderide/src/camera/projection.rs
index 7b625be87..534bb294a 100644
--- a/crates/renderide/src/camera/projection.rs
+++ b/crates/renderide/src/camera/projection.rs
@@ -304,8 +304,7 @@ mod projection_math_tests {
     #[test]
     fn skybox_shader_uses_positive_asymmetric_skew_sign() {
         let source = include_str!("../../shaders/modules/skybox/common.wgsl");
-        assert!(source.contains("ndc.x + proj_params.z"));
-        assert!(source.contains("ndc.y + proj_params.w"));
+        assert!(source.contains("ndc.xy + proj_params.zw"));
     }
 
     /// Orthographic skyboxes use a parallel view ray instead of unprojecting NDC as a perspective
diff --git a/crates/renderide/src/passes/world_mesh_forward/skybox.rs b/crates/renderide/src/passes/world_mesh_forward/skybox.rs
index 3fa28524d..6a9eb8c1c 100644
--- a/crates/renderide/src/passes/world_mesh_forward/skybox.rs
+++ b/crates/renderide/src/passes/world_mesh_forward/skybox.rs
@@ -428,8 +428,7 @@ mod tests {
 
     #[test]
     fn skybox_view_uniforms_are_16_byte_aligned() {
-        assert_eq!(size_of::<SkyboxViewUniforms>() % 16, 0);
-        assert_eq!(SKYBOX_VIEW_UNIFORM_SIZE, 128);
+        assert_eq!(SKYBOX_VIEW_UNIFORM_SIZE % 16, 0);
     }
 
     #[test]
diff --git a/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs b/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs
index e4cda7ba7..95044947c 100644
--- a/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs
+++ b/crates/renderide/src/passes/world_mesh_forward/skybox/pipeline.rs
@@ -47,10 +47,8 @@ impl SkyboxFamily {
 
     /// Vertex count used by the fullscreen background draw.
     pub(super) const fn draw_vertex_count(self) -> u32 {
-        match self {
-            Self::Projection360 | Self::Gradient => 3,
-            Self::Procedural => 3,
-        }
+        // A single triangle encompassing the viewport
+        3
     }
 }
 
@@ -211,7 +209,7 @@ mod tests {
     fn procedural_skybox_draws_fullscreen_quad() {
         assert_eq!(SkyboxFamily::Projection360.draw_vertex_count(), 3);
         assert_eq!(SkyboxFamily::Gradient.draw_vertex_count(), 3);
-        assert_eq!(SkyboxFamily::Procedural.draw_vertex_count(), 6);
+        assert_eq!(SkyboxFamily::Procedural.draw_vertex_count(), 3);
     }
 
     #[test]

From 06faf5ad5122bf18fa2257700922b0d0011d3b43 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Thu, 21 May 2026 17:56:02 +0200
Subject: [PATCH 11/12] Add defaults and pass types for skybox materials

---
 .../passes/backend/skybox_gradientskybox.wgsl  |  1 +
 .../backend/skybox_proceduralskybox.wgsl       |  9 +++++++++
 .../passes/backend/skybox_projection360.wgsl   | 18 ++++++++++++++++++
 .../passes/backend/skybox_solid_color.wgsl     |  1 +
 4 files changed, 29 insertions(+)

diff --git a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
index bcfb2fb7e..258c4d3f3 100644
--- a/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_gradientskybox.wgsl
@@ -40,6 +40,7 @@ fn vs_main(
     return out;
 }
 
+//#pass type=forward blend=off zwrite=off ztest=main
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let ndc = skybox::ndc_from_clip(in.clip_pos);
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 53003e819..5d9482a29 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -3,6 +3,14 @@
 //! The shared ProceduralSkybox material module owns the reflected `@group(1)` contract and
 //! shader-specific keyword decoding for both this pass-side sky draw and the material root.
 
+//#mat_default _SkyTint vec4 0.5 0.5 0.5 1.0
+//#mat_default _GroundColor vec4 0.369 0.349 0.341 1.0
+//#mat_default _SunColor vec4 1.0 1.0 1.0 1.0
+//#mat_default _SunDirection vec4 0.577 0.577 0.577 0.0
+//#mat_default _Exposure float 1.3
+//#mat_default _SunSize float 0.04
+//#mat_default _AtmosphereThickness float 1.0
+
 #import renderide::frame::globals as rg
 #import renderide::core::fullscreen as fs
 #import renderide::skybox::procedural as ps
@@ -35,6 +43,7 @@ fn vs_main(
     return out;
 }
 
+//#pass type=forward blend=off zwrite=off ztest=main
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let ndc = skybox::ndc_from_clip(in.clip_pos);
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index 8fc14c60c..e692d3f22 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -3,6 +3,23 @@
 //! The shared Projection360 module owns shader-specific keyword decoding and projection
 //! sampling for both this pass-side sky draw and the material root.
 
+//#texture_default _MainTex black
+//#texture_default _SecondTex black
+//#texture_default _TintTex white
+//#texture_default _OffsetTex black
+//#texture_default _OffsetMask white
+//#texture_default _MainCube black
+//#texture_default _SecondCube black
+//#mat_default _Exposure float 1.0
+//#mat_default _FOV vec4 6.283185 3.141593 0.0 0.0
+//#mat_default _Gamma float 1.0
+//#mat_default _MaxIntensity float 4.0
+//#mat_default _OffsetMagnitude vec4 0.1 0.1 0.0 0.0
+//#mat_default _PerspectiveFOV vec4 0.785398 0.785398 0.0 0.0
+//#mat_default _Tint vec4 1.0 1.0 1.0 1.0
+//#mat_default _Tint0 vec4 1.0 0.0 0.0 1.0
+//#mat_default _Tint1 vec4 0.0 1.0 0.0 1.0
+
 #import renderide::frame::globals as rg
 #import renderide::core::fullscreen as fs
 #import renderide::skybox::common as skybox
@@ -113,6 +130,7 @@ fn vs_main(
     return out;
 }
 
+//#pass type=forward blend=off zwrite=off ztest=material(main)
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let params = projection360_params();
diff --git a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
index e4398bed5..d05f36b51 100644
--- a/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_solid_color.wgsl
@@ -16,6 +16,7 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32) -> VertexOutput {
     return out;
 }
 
+//#pass type=forward blend=off zwrite=off ztest=main
 @fragment
 fn fs_main(_in: VertexOutput) -> @location(0) vec4<f32> {
     return view.clear_color;

From 29af598d2a998583ffe3443ad612deb5eb70eca3 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Thu, 21 May 2026 17:57:46 +0200
Subject: [PATCH 12/12] Workaround Projection 360 skybox z-fighting with clip
 far plane

---
 crates/renderide/shaders/modules/core/math.wgsl             | 2 ++
 .../shaders/passes/backend/skybox_projection360.wgsl        | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/crates/renderide/shaders/modules/core/math.wgsl b/crates/renderide/shaders/modules/core/math.wgsl
index fa03433f6..1296f564d 100644
--- a/crates/renderide/shaders/modules/core/math.wgsl
+++ b/crates/renderide/shaders/modules/core/math.wgsl
@@ -4,6 +4,8 @@
 
 const EPSILON: f32 = 1e-6;
 
+const MIN_FLOAT: f32 = 0x1p-126f;
+
 fn saturate(v: f32) -> f32 {
     return clamp(v, 0.0, 1.0);
 }
diff --git a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
index e692d3f22..aba5e2432 100644
--- a/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_projection360.wgsl
@@ -22,6 +22,7 @@
 
 #import renderide::frame::globals as rg
 #import renderide::core::fullscreen as fs
+#import renderide::core::math as math
 #import renderide::skybox::common as skybox
 #import renderide::skybox::projection360 as p360
 #import renderide::skybox::projection360_material as p360m
@@ -121,7 +122,10 @@ fn vs_main(
 ) -> VertexOutput {
     let clip = fs::fullscreen_clip_pos(vertex_index);
     var out: VertexOutput;
-    out.clip_pos = clip;
+    /// Add MIN_FLOAT to avoid Z-fighting with far plane
+    /// when using wgpu::CompareFunction::Greater
+    /// i.e. with FrooxEngine ZTest enum LessOrEqual
+    out.clip_pos = clip + vec4<f32>(0.0, 0.0, math::MIN_FLOAT, 0.0);
 #ifdef MULTIVIEW
     out.view_layer = view_idx;
 #else