From 8c3d87f6459c1c99377ccf99d41d0a7fc564e1c0 Mon Sep 17 00:00:00 2001
From: Baplar <me@baplar.fr>
Date: Thu, 4 Jun 2026 15:30:17 +0200
Subject: [PATCH] Fix skyboxes in orthographic camera projection

---
 crates/renderide/shaders/modules/skybox/common.wgsl         | 2 +-
 .../shaders/passes/backend/skybox_proceduralskybox.wgsl     | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/crates/renderide/shaders/modules/skybox/common.wgsl b/crates/renderide/shaders/modules/skybox/common.wgsl
index 047526175..ac651a112 100644
--- a/crates/renderide/shaders/modules/skybox/common.wgsl
+++ b/crates/renderide/shaders/modules/skybox/common.wgsl
@@ -42,7 +42,7 @@ 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>(ndc.xy, -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.
diff --git a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
index 44f3e8e52..336a545f5 100644
--- a/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
+++ b/crates/renderide/shaders/passes/backend/skybox_proceduralskybox.wgsl
@@ -106,12 +106,14 @@ fn clip_pos_from_view_ray(
     orthographic: bool,
 ) -> vec4<f32> {
     if (view_ray.z >= -1e-6) {
+        // Send point behind near plane
         return vec4<f32>(view_ray.xy, 2.0, 1.0);
     }
+    let camera_ray = view_ray.xy / (-view_ray.z);
     if (orthographic) {
-        return vec4<f32>(sign(view_ray.xy), 0.0, 1.0);
+        return vec4<f32>(camera_ray * sign(proj_params.xy), 0.0, 1.0);
     }
-    return vec4<f32>(view_ray.xy * proj_params.xy / (-view_ray.z) - proj_params.zw, 0.0, 1.0);
+    return vec4<f32>(camera_ray * proj_params.xy - proj_params.zw, 0.0, 1.0);
 }
 
 fn view_ray_from_world_ray(world_ray: vec3<f32>, view_layer: u32) -> vec3<f32> {