From d6660f88ed752dff430ca896d1681a34c6fd9d77 Mon Sep 17 00:00:00 2001
From: David Carter <dcarter@davidcarter.ca>
Date: Mon, 28 Oct 2024 13:05:48 -0400
Subject: [PATCH] Materials: Selectively apply appearances

Change the appearance only if the appearance hasn't been set explicitly.
A cached material appearance is used to see if the current appearance
matches the last material. It is also compared against an empty
material to see if the saved material value has been initialized.

This solves the problem of material changes overwriting appearance
changes
---
 src/Gui/ViewProviderGeometryObject.cpp | 13 ++++++++++++-
 src/Gui/ViewProviderGeometryObject.h   |  2 ++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/Gui/ViewProviderGeometryObject.cpp b/src/Gui/ViewProviderGeometryObject.cpp
index d7c1754c15..d4d4cba0e3 100644
--- a/src/Gui/ViewProviderGeometryObject.cpp
+++ b/src/Gui/ViewProviderGeometryObject.cpp
@@ -188,8 +188,19 @@ void ViewProviderGeometryObject::updateData(const App::Property* prop)
         // Set the appearance from the material
         auto geometry = dynamic_cast<App::GeoFeature*>(getObject());
         if (geometry) {
+            /*
+             * Change the appearance only if the appearance hasn't been set explicitly. A cached
+             * material appearance is used to see if the current appearance matches the last
+             * material. It is also compared against an empty material to see if the saved
+             * material value has been initialized.
+             */
+            App::Material defaultMaterial;
             auto material = geometry->getMaterialAppearance();
-            ShapeAppearance.setValue(material);
+            if ((materialAppearance == defaultMaterial)
+                || (ShapeAppearance.getSize() == 1 && ShapeAppearance[0] == materialAppearance)) {
+                ShapeAppearance.setValue(material);
+            }
+            materialAppearance = material;
         }
     }
 
diff --git a/src/Gui/ViewProviderGeometryObject.h b/src/Gui/ViewProviderGeometryObject.h
index 607cd42d2f..3561b1178a 100644
--- a/src/Gui/ViewProviderGeometryObject.h
+++ b/src/Gui/ViewProviderGeometryObject.h
@@ -116,6 +116,8 @@ protected:
     SoFCBoundingBox* pcBoundingBox {nullptr};
     SoSwitch* pcBoundSwitch {nullptr};
     SoBaseColor* pcBoundColor {nullptr};
+
+    App::Material materialAppearance;
 };
 
 }  // namespace Gui