Fix property lookup for effects

There could be multilayered inheritance structure on top of
QQuick3DEffect, so account for that when determining which properties
need to be added as uniforms.

Task-number: QDS-2114
Change-Id: I3f89bc1ff6070890829575d66c127d269de7edab
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>
Reviewed-by: Antti Määttä <antti.maatta@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
(cherry picked from commit 5c0c79ea)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/quick3d/qquick3deffect.cpp

@@ -258,7 +258,15 @@ QSSGRenderGraphObject *QQuick3DEffect::updateSpatialNode(QSSGRenderGraphObject *
         // Properties -> uniforms
         QByteArray uniforms;
         const int propCount = metaObject()->propertyCount();
-        const int propOffset = metaObject()->propertyOffset();
+        int propOffset = metaObject()->propertyOffset();
+
+        // Effect can have multilayered inheritance structure, so find the actual propOffset
+        const QMetaObject *superClass = metaObject()->superClass();
+        while (superClass && qstrcmp(superClass->className(), "QQuick3DEffect") != 0)  {
+            propOffset = superClass->propertyOffset();
+            superClass = superClass->superClass();
+        }
+
         QVector<QMetaProperty> textureProperties; // We'll deal with these later
         for (int i = propOffset; i != propCount; ++i) {
             const auto property = metaObject()->property(i);