From 6c80e24b38665876d7ce0df4dc5b385e74f43d62 Mon Sep 17 00:00:00 2001
From: Zhaoxi Chen <35674081+FrozenBurning@users.noreply.github.com>
Date: Sat, 13 Jul 2024 14:12:26 +0800
Subject: [PATCH] Update visual.gloss.specular_to_pbr to align gltf 2.0
 material specs

---
 tests/test_gltf.py      | 3 ++-
 trimesh/visual/gloss.py | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/test_gltf.py b/tests/test_gltf.py
index 8794c48bd..10207f895 100644
--- a/tests/test_gltf.py
+++ b/tests/test_gltf.py
@@ -307,7 +307,8 @@ def test_specular_glossiness(self):
         )
         assert metallic_roughness.shape[0] == 84 and metallic_roughness.shape[1] == 71
 
-        metallic = metallic_roughness[:, :, 0]
+        # https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#metallic-roughness-material
+        metallic = metallic_roughness[:, :, 2]
         roughness = metallic_roughness[:, :, 1]
 
         assert g.np.allclose(metallic[0, 0], 0.231, atol=0.004)
diff --git a/trimesh/visual/gloss.py b/trimesh/visual/gloss.py
index 8c4065685..ffad0e125 100644
--- a/trimesh/visual/gloss.py
+++ b/trimesh/visual/gloss.py
@@ -360,7 +360,7 @@ def convert_texture_lin2srgb(texture):
         # we need to use RGB textures, because 2 channel textures can cause problems
         result["metallicRoughnessTexture"] = toPIL(
             np.concatenate(
-                [metallic, 1.0 - glossiness, np.zeros_like(metallic)], axis=-1
+                [np.zeros_like(metallic), 1.0 - glossiness, metallic], axis=-1
             ),
             mode="RGB",
         )