Material: Material appearance

Uses new material system for appearance

Each feature object now has a property called ShapeMaterial that
describes its physical properties. If it has a shape, it has a
material.

The ShapeColor attribute is replaced by a ShapeAppearance attribute.
This is a material list that describes all appearance properties, not
just diffuse color. As a list in can be used for all elements of a
shape, such as edges and faces.

A new widget is provided to allow the user to select materials in a
consistent fashion. It can also launch the material editor with its
more advanced capabilities.

src/Gui/ViewProviderGeometryObjectPyImp.cpp

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+/***************************************************************************
+ *   Copyright (c) 2024 Werner Mayer <wmayer[at]users.sourceforge.net>     *
+ *                                                                         *
+ *   This file is part of FreeCAD.                                         *
+ *                                                                         *
+ *   FreeCAD is free software: you can redistribute it and/or modify it    *
+ *   under the terms of the GNU Lesser General Public License as           *
+ *   published by the Free Software Foundation, either version 2.1 of the  *
+ *   License, or (at your option) any later version.                       *
+ *                                                                         *
+ *   FreeCAD is distributed in the hope that it will be useful, but        *
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of            *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      *
+ *   Lesser General Public License for more details.                       *
+ *                                                                         *
+ *   You should have received a copy of the GNU Lesser General Public      *
+ *   License along with FreeCAD. If not, see                               *
+ *   <https://www.gnu.org/licenses/>.                                      *
+ *                                                                         *
+ **************************************************************************/
+
+#include "PreCompiled.h"
+
+#ifndef _PreComp_
+#include <sstream>
+#endif
+
+#include <App/GeoFeature.h>
+#include <App/PropertyStandard.h>
+
+#include "ViewProviderGeometryObjectPy.h"
+
+#include "ViewProviderGeometryObjectPy.cpp"
+
+
+using namespace Gui;
+
+// returns a string which represents the object e.g. when printed in python
+std::string ViewProviderGeometryObjectPy::representation() const
+{
+    std::stringstream str;
+    str << "<View provider geometry object at " << getViewProviderGeometryObjectPtr() << ">";
+
+    return str.str();
+}
+
+PyObject* ViewProviderGeometryObjectPy::getCustomAttributes(const char* attr) const
+{
+    ViewProviderGeometryObject* vp = getViewProviderGeometryObjectPtr();
+    if (strcmp(attr, "ShapeColor") == 0) {
+        // Get material property of ViewProviderGeometryObject
+        App::PropertyColor prop;
+        prop.setValue(vp->ShapeAppearance.getDiffuseColor());
+        return prop.getPyObject();
+    }
+    if (strcmp(attr, "ShapeMaterial") == 0) {
+        // Get material property of ViewProviderGeometryObject
+        auto geometry = dynamic_cast<App::GeoFeature*>(vp->getObject());
+        if (geometry) {
+            auto material = geometry->getMaterialAppearance();
+            App::PropertyMaterial prop;
+            prop.setValue(material);
+            return prop.getPyObject();
+        }
+    }
+    return nullptr;
+}
+
+int ViewProviderGeometryObjectPy::setCustomAttributes(const char* attr, PyObject* obj)
+{
+    ViewProviderGeometryObject* vp = getViewProviderGeometryObjectPtr();
+    if (strcmp(attr, "ShapeColor") == 0) {
+        // Get material property of ViewProviderGeometryObject
+        App::PropertyColor prop;
+        prop.setPyObject(obj);
+        vp->ShapeAppearance.setDiffuseColor(prop.getValue());
+        // Assign the value to the new property type
+        // ...
+        return 1;
+    }
+    if (strcmp(attr, "ShapeMaterial") == 0) {
+        // Get material property of ViewProviderGeometryObject
+        auto geometry = dynamic_cast<App::GeoFeature*>(vp->getObject());
+        if (geometry) {
+            App::PropertyMaterial prop;
+            prop.setPyObject(obj);
+            geometry->setMaterialAppearance(prop.getValue());
+        }
+        return 1;
+    }
+    return 0;
+}