From 2731017aa88bf6baaff787d7486d4248f9ca6ca0 Mon Sep 17 00:00:00 2001
From: metamuffin <metamuffin@disroot.org>
Date: Sun, 12 Jan 2025 20:33:59 +0100
Subject: double sided mesh attribute

---
 doc/resources.md        | 3 +++
 shared/src/resources.rs | 1 +
 world/src/mesh.rs       | 8 ++++++++
 3 files changed, 12 insertions(+)

diff --git a/doc/resources.md b/doc/resources.md
index d3d33eb..61a5781 100644
--- a/doc/resources.md
+++ b/doc/resources.md
@@ -48,6 +48,7 @@ white except normals are zero.
 | `g_dispersion`       | `Float`        |                    |
 | `g_thickness`        | `Float`        |                    |
 | `g_unlit`            |                |                    |
+| `g_double_sided`     |                |                    |
 | `va_position`        | `Res<[Vec3]>`  |                    |
 | `va_normal`          | `Res<[Vec3]>`  |                    |
 | `va_texcoord`        | `Res<[Vec2]>`  |                    |
@@ -79,6 +80,8 @@ white except normals are zero.
   [KHR_materials_dispersion].
 - **Unlit**: Directly transfers \*_albedo to the screen if set. No lighting
   shaders are applied. See [KHR_materials_unlit]
+- **Double Sided**: Disable backface culling for this mesh. Equivalent to
+  `material.doubleSided` of glTF 2.0.
 
 ## LightPart
 
diff --git a/shared/src/resources.rs b/shared/src/resources.rs
index f9e7242..ba45284 100644
--- a/shared/src/resources.rs
+++ b/shared/src/resources.rs
@@ -59,6 +59,7 @@ pub struct MeshPart {
     pub g_attenuation: Option<Vec3A>,
     pub g_dispersion: Option<f32>,
     pub g_unlit: Option<()>,
+    pub g_double_sided: Option<()>,
     pub va_position: Option<Resource<Vec<Vec3A>>>,
     pub va_normal: Option<Resource<Vec<Vec3A>>>,
     pub va_texcoord: Option<Resource<Vec<Vec2>>>,
diff --git a/world/src/mesh.rs b/world/src/mesh.rs
index f66be82..fd6b6ae 100644
--- a/world/src/mesh.rs
+++ b/world/src/mesh.rs
@@ -298,6 +298,13 @@ pub fn import_mesh(
             None
         };
 
+        let g_double_sided = if p.material().double_sided() {
+            info!("double sided");
+            Some(())
+        } else {
+            None
+        };
+
         let mesh = store.set(&MeshPart {
             name,
             index,
@@ -312,6 +319,7 @@ pub fn import_mesh(
             g_refractive_index,
             g_dispersion,
             g_unlit,
+            g_double_sided,
             va_position,
             va_normal,
             va_texcoord,
-- 
cgit v1.2.3-70-g09d2