Apply sheen feedback.

KhronosGroup · Mar 7, 2022 · 45a2fdf · 45a2fdf
1 parent 59a5051
commit 45a2fdf
Showing 1 changed file with 23 additions and 8 deletions.
diff --git a/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py b/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py
@@ -323,8 +323,22 @@ def __gather_clearcoat_extension(blender_material, export_settings):
 
     return Extension('KHR_materials_clearcoat', clearcoat_extension, False)
 
+# See: https://github.com/sobotka/blender/blob/4dd1068a5789097b50eab159adc995906fa5ea84/source/blender/gpu/shaders/material/gpu_shader_material_principled.glsl#L2-L6
+def __tint_from_color(color):
+    # Luminance approximation.
+    luminance = color[0] * 0.3 + color[1] * 0.6 + color[2] * 0.1
+
+    if luminance > 0:
+        # Normalize to isolate hue and saturation.
+        return [
+            color[0] / luminance,
+            color[1] / luminance,
+            color[2] / luminance
+        ]
+
+    return [1, 1, 1]
+
 def __gather_sheen_extension(blender_material, export_settings):
-    sheen_enabled = False
     sheen_extension = {}
 
     sheen_socket = gltf2_blender_get.get_socket(blender_material, 'Sheen')
@@ -333,21 +347,22 @@ def __gather_sheen_extension(blender_material, export_settings):
     if (isinstance(sheen_socket, bpy.types.NodeSocket)
             and isinstance(sheen_tint_socket, bpy.types.NodeSocket)
             and isinstance(base_color_socket, bpy.types.NodeSocket)):
-        sheen = gltf2_blender_get.get_factor_from_socket(sheen_socket, 'VALUE') or 0
-        tint = gltf2_blender_get.get_factor_from_socket(sheen_tint_socket, 'VALUE') or 0
-        base_color = gltf2_blender_get.get_factor_from_socket(base_color_socket, 'RGB') or [1, 1, 1]
+        sheen = gltf2_blender_get.get_factor_from_socket(sheen_socket, kind='VALUE') or 0
+        tint = gltf2_blender_get.get_factor_from_socket(sheen_tint_socket, kind='VALUE') or 0
+        base_color = gltf2_blender_get.get_factor_from_socket(base_color_socket, kind='RGB') or [1, 1, 1]
+        base_color_tint = __tint_from_color(base_color)
         sheen_extension['sheenColorFactor'] = [
-            sheen * ((1 - tint) + (tint * base_color[0])),
-            sheen * ((1 - tint) + (tint * base_color[1])),
-            sheen * ((1 - tint) + (tint * base_color[2]))
+            max(0, min(1, sheen * ((1 - tint) + (tint * base_color_tint[0])))),
+            max(0, min(1, sheen * ((1 - tint) + (tint * base_color_tint[1])))),
+            max(0, min(1, sheen * ((1 - tint) + (tint * base_color_tint[2])))),
         ]
 
     if not any(sheen_extension['sheenColorFactor']):
         return None
 
     roughness_socket = gltf2_blender_get.get_socket(blender_material, 'Roughness')
     if isinstance(roughness_socket, bpy.types.NodeSocket) and not roughness_socket.is_linked:
-        sheen_extension['sheenRoughnessFactor'] = gltf2_blender_get.get_factor_from_socket(roughness_socket, 'VALUE')
+        sheen_extension['sheenRoughnessFactor'] = gltf2_blender_get.get_factor_from_socket(roughness_socket, kind='VALUE')
 
     return Extension('KHR_materials_sheen', sheen_extension, False)