Atom Tools: Restoring idle behavior for viewport input behavior controller

Signed-off-by: Guthrie Adams <guthadam@amazon.com>

Gems/Atom/Tools/AtomToolsFramework/Code/Include/AtomToolsFramework/Viewport/ViewportInputBehaviorController/IdleBehavior.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#pragma once
+
+#include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/ViewportInputBehavior.h>
+
+namespace AtomToolsFramework
+{
+    class IdleBehavior final : public ViewportInputBehavior
+    {
+    public:
+        IdleBehavior(ViewportInputBehaviorControllerInterface* controller);
+        virtual ~IdleBehavior() = default;
+    };
+} // namespace AtomToolsFramework

Gems/Atom/Tools/AtomToolsFramework/Code/Source/Viewport/ViewportInputBehaviorController/IdleBehavior.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/IdleBehavior.h>
+#include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/ViewportInputBehaviorControllerInterface.h>
+
+namespace AtomToolsFramework
+{
+    IdleBehavior::IdleBehavior(ViewportInputBehaviorControllerInterface* controller)
+        : ViewportInputBehavior(controller)
+    {
+    }
+} // namespace AtomToolsFramework

Gems/Atom/Tools/AtomToolsFramework/Code/Source/Viewport/ViewportInputBehaviorController/ViewportInputBehaviorController.cpp

@@ -280,8 +280,14 @@ namespace AtomToolsFramework
     void ViewportInputBehaviorController::EvaluateControlBehavior()
     {
         auto it = m_behaviorMap.find(m_keys);
+        if (it == m_behaviorMap.end())
+        {
+            it = m_behaviorMap.find(None);
+        }
+
         AZStd::shared_ptr<ViewportInputBehavior> nextBehavior =
             it != m_behaviorMap.end() ? it->second : AZStd::shared_ptr<ViewportInputBehavior>();
+
         if (m_behavior != nextBehavior)
         {
             if (m_behavior)

Gems/Atom/Tools/AtomToolsFramework/Code/atomtoolsframework_files.cmake

@@ -95,6 +95,8 @@ set(FILES
     Include/AtomToolsFramework/Viewport/ViewportInputBehaviorController/ViewportInputBehavior.h
     Source/Viewport/ViewportInputBehaviorController/DollyCameraBehavior.cpp
     Include/AtomToolsFramework/Viewport/ViewportInputBehaviorController/DollyCameraBehavior.h
+    Source/Viewport/ViewportInputBehaviorController/IdleBehavior.cpp
+    Include/AtomToolsFramework/Viewport/ViewportInputBehaviorController/IdleBehavior.h
     Source/Viewport/ViewportInputBehaviorController/MoveCameraBehavior.cpp
     Include/AtomToolsFramework/Viewport/ViewportInputBehaviorController/MoveCameraBehavior.h
     Source/Viewport/ViewportInputBehaviorController/PanCameraBehavior.cpp

Gems/Atom/Tools/MaterialEditor/Code/Source/Viewport/MaterialViewportWidget.cpp

@@ -41,6 +41,7 @@
 #include <AtomLyIntegration/CommonFeatures/PostProcess/ExposureControl/ExposureControlComponentConstants.h>
 #include <AtomLyIntegration/CommonFeatures/PostProcess/PostFxLayerComponentConstants.h>
 #include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/DollyCameraBehavior.h>
+#include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/IdleBehavior.h>
 #include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/MoveCameraBehavior.h>
 #include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/OrbitCameraBehavior.h>
 #include <AtomToolsFramework/Viewport/ViewportInputBehaviorController/PanCameraBehavior.h>
@@ -312,6 +313,8 @@ namespace MaterialEditor
         // Create viewport input controller and regioster its behaviors
         m_viewportController.reset(
             aznew ViewportInputBehaviorController(m_cameraEntity->GetId(), m_modelEntity->GetId(), m_iblEntity->GetId()));
+        m_viewportController->AddBehavior(
+            ViewportInputBehaviorController::None, AZStd::make_shared<IdleBehavior>(m_viewportController.get()));
         m_viewportController->AddBehavior(
             ViewportInputBehaviorController::Lmb, AZStd::make_shared<PanCameraBehavior>(m_viewportController.get()));
         m_viewportController->AddBehavior(