[ATOM-15538] Material Editor camera zoom speed adjusts to model size

Gems/Atom/Tools/MaterialEditor/Code/Include/Atom/Viewport/InputController/MaterialEditorViewportInputControllerBus.h

@@ -47,6 +47,9 @@ namespace MaterialEditor
         //! @param distanceMax furthest camera can be from the target
         virtual void GetExtents(float& distanceMin, float& distanceMax) const = 0;
 
+        //! Get bounding sphere radius of the active model
+        virtual float GetRadius() const = 0;
+
         //! Reset camera to default position and rotation 
         virtual void Reset() = 0;
 

Gems/Atom/Tools/MaterialEditor/Code/Source/Viewport/InputController/Behavior.cpp

@@ -44,6 +44,8 @@ namespace MaterialEditor
         MaterialEditorViewportInputControllerRequestBus::BroadcastResult(
             m_targetPosition,
             &MaterialEditorViewportInputControllerRequestBus::Handler::GetTargetPosition);
+        MaterialEditorViewportInputControllerRequestBus::BroadcastResult(
+            m_radius, &MaterialEditorViewportInputControllerRequestBus::Handler::GetRadius);
     }
 
     void Behavior::End()
@@ -119,7 +121,7 @@ namespace MaterialEditor
 
     float Behavior::GetSensitivityZ()
     {
-        return 0.001f;
+        return 0.001f * AZ::GetMax(0.5f, m_radius);
     }
 
     AZ::Quaternion Behavior::LookRotation(AZ::Vector3 forward)

Gems/Atom/Tools/MaterialEditor/Code/Source/Viewport/InputController/Behavior.h

@@ -54,6 +54,8 @@ namespace MaterialEditor
         float m_y = 0;
         //! delta scroll wheel accumulated during current frame
         float m_z = 0;
+        //! Model radius
+        float m_radius = 1.0f;
 
         AZ::EntityId m_cameraEntityId;
         AZ::Vector3 m_targetPosition = AZ::Vector3::CreateZero();

Gems/Atom/Tools/MaterialEditor/Code/Source/Viewport/InputController/MaterialEditorViewportInputController.cpp

@@ -114,6 +114,11 @@ namespace MaterialEditor
         distanceMax = m_distanceMax;
     }
 
+    float MaterialEditorViewportInputController::GetRadius() const
+    {
+        return m_radius;
+    }
+
     void MaterialEditorViewportInputController::UpdateViewport(const AzFramework::ViewportControllerUpdateEvent& event)
     {
         if (m_keysChanged)
@@ -306,11 +311,10 @@ namespace MaterialEditor
             if (modelAsset.IsReady())
             {
                 const AZ::Aabb& aabb = modelAsset->GetAabb();
-                float radius;
-                aabb.GetAsSphere(m_modelCenter, radius);
+                aabb.GetAsSphere(m_modelCenter, m_radius);
 
                 m_distanceMin = 0.5f * AZ::GetMin(AZ::GetMin(aabb.GetExtents().GetX(), aabb.GetExtents().GetY()), aabb.GetExtents().GetZ()) + DepthNear;
-                m_distanceMax = radius * MaxDistanceMultiplier;
+                m_distanceMax = m_radius * MaxDistanceMultiplier;
             }
         }
     }

Gems/Atom/Tools/MaterialEditor/Code/Source/Viewport/InputController/MaterialEditorViewportInputController.h

@@ -43,6 +43,7 @@ namespace MaterialEditor
         void SetTargetPosition(const AZ::Vector3& targetPosition) override;
         float GetDistanceToTarget() const override;
         void GetExtents(float& distanceMin, float& distanceMax) const override;
+        float GetRadius() const override;
         void Reset() override;
         void SetFieldOfView(float value) override;
         bool IsCameraCentered() const override;
@@ -96,6 +97,8 @@ namespace MaterialEditor
         float m_distanceMin = 1.0f;
         //! Maximum distance from camera to target
         float m_distanceMax = 10.0f;
+        //! Model radius
+        float m_radius = 1.0f;
         //! True if camera is centered on a model
         bool m_isCameraCentered = true;