Fix camera drift issues (#4576)

* remove some unused code in RenderViewportWidget and make viewing devicePixelRatioF easier

Signed-off-by: hultonha <hultonha@amazon.co.uk>

* updates to how cursor positions are calculate to handle the viewport widget moving

Signed-off-by: hultonha <hultonha@amazon.co.uk>

* remove optional for previous position

Signed-off-by: hultonha <hultonha@amazon.co.uk>

* add test to capture error with moving the widget

Signed-off-by: hultonha <hultonha@amazon.co.uk>

* minor comment updates before publishing PR

Signed-off-by: hultonha <hultonha@amazon.co.uk>

Code/Editor/Lib/Tests/test_ModularViewportCameraController.cpp

@@ -69,6 +69,7 @@ namespace UnitTest
 
             m_rootWidget = AZStd::make_unique<QWidget>();
             m_rootWidget->setFixedSize(WidgetSize);
+            m_rootWidget->move(0, 0); // explicitly set the widget to be in the upper left corner
 
             m_controllerList = AZStd::make_shared<AzFramework::ViewportControllerList>();
             m_controllerList->RegisterViewportContext(TestViewportId);
@@ -344,4 +345,51 @@ namespace UnitTest
         // Clean-up
         HaltCollaborators();
     }
+
+    // test to verify deltas and cursor positions are handled correctly when the widget is moved
+    TEST_F(ModularViewportCameraControllerFixture, CameraDoesNotStutterAfterWidgetIsMoved)
+    {
+        // Given
+        PrepareCollaborators();
+        SandboxEditor::SetCameraCaptureCursorForLook(true);
+
+        const float deltaTime = 1.0f / 60.0f;
+
+        // When
+        // move cursor to the center of the screen
+        auto start = QPoint(WidgetSize.width() / 2, WidgetSize.height() / 2);
+        MouseMove(m_rootWidget.get(), start, QPoint(0, 0));
+        m_controllerList->UpdateViewport({ TestViewportId, AzFramework::FloatSeconds(deltaTime), AZ::ScriptTimePoint() });
+
+        // move camera right
+        const auto mouseDelta = QPoint(200, 0);
+        MousePressAndMove(m_rootWidget.get(), start, mouseDelta, Qt::MouseButton::RightButton);
+        m_controllerList->UpdateViewport({ TestViewportId, AzFramework::FloatSeconds(deltaTime), AZ::ScriptTimePoint() });
+
+        QTest::mouseRelease(m_rootWidget.get(), Qt::MouseButton::RightButton, Qt::NoModifier, start + mouseDelta);
+
+        // update the position of the widget
+        const auto offset = QPoint(500, 500);
+        m_rootWidget->move(offset);
+
+        // move cursor back to widget center
+        MouseMove(m_rootWidget.get(), start, QPoint(0, 0));
+        m_controllerList->UpdateViewport({ TestViewportId, AzFramework::FloatSeconds(deltaTime), AZ::ScriptTimePoint() });
+
+        // move camera left
+        MousePressAndMove(m_rootWidget.get(), start, -mouseDelta, Qt::MouseButton::RightButton);
+        m_controllerList->UpdateViewport({ TestViewportId, AzFramework::FloatSeconds(deltaTime), AZ::ScriptTimePoint() });
+
+        // Then
+        // ensure the camera rotation has returned to the identity
+        const AZ::Quaternion cameraRotation = m_cameraViewportContextView->GetCameraTransform().GetRotation();
+        const auto eulerAngles = AzFramework::EulerAngles(AZ::Matrix3x3::CreateFromQuaternion(cameraRotation));
+
+        using ::testing::FloatNear;
+        EXPECT_THAT(eulerAngles.GetX(), FloatNear(0.0f, 0.001f));
+        EXPECT_THAT(eulerAngles.GetZ(), FloatNear(0.0f, 0.001f));
+
+        // Clean-up
+        HaltCollaborators();
+    }
 } // namespace UnitTest

Code/Framework/AzToolsFramework/AzToolsFramework/Input/QtEventToAzInputManager.cpp

@@ -261,10 +261,10 @@ namespace AzToolsFramework
             // ensures cursor positions are refreshed correctly with context menu focus changes)
             if (eventType == QEvent::FocusIn)
             {
-                const auto widgetCursorPosition = m_sourceWidget->mapFromGlobal(QCursor::pos());
-                if (m_sourceWidget->geometry().contains(widgetCursorPosition))
+                const auto globalCursorPosition = QCursor::pos();
+                if (m_sourceWidget->geometry().contains(globalCursorPosition))
                 {
-                    HandleMouseMoveEvent(widgetCursorPosition);
+                    HandleMouseMoveEvent(globalCursorPosition);
                 }
             }
         }
@@ -290,7 +290,7 @@ namespace AzToolsFramework
         else if (eventType == QEvent::Type::MouseMove)
         {
             auto mouseEvent = static_cast<QMouseEvent*>(event);
-            HandleMouseMoveEvent(mouseEvent->pos());
+            HandleMouseMoveEvent(mouseEvent->globalPos());
         }
         // Map wheel events to the mouse Z movement channel.
         else if (eventType == QEvent::Type::Wheel)
@@ -370,11 +370,12 @@ namespace AzToolsFramework
         return QPoint{ denormalizedX, denormalizedY };
     }
 
-    void QtEventToAzInputMapper::HandleMouseMoveEvent(const QPoint& cursorPosition)
+    void QtEventToAzInputMapper::HandleMouseMoveEvent(const QPoint& globalCursorPosition)
     {
-        const QPoint cursorDelta = cursorPosition - m_previousCursorPosition;
+        const QPoint cursorDelta = globalCursorPosition - m_previousGlobalCursorPosition;
 
-        m_mouseDevice->m_cursorPositionData2D->m_normalizedPosition = WidgetPositionToNormalizedPosition(cursorPosition);
+        m_mouseDevice->m_cursorPositionData2D->m_normalizedPosition =
+            WidgetPositionToNormalizedPosition(m_sourceWidget->mapFromGlobal(globalCursorPosition));
         m_mouseDevice->m_cursorPositionData2D->m_normalizedPositionDelta = WidgetPositionToNormalizedPosition(cursorDelta);
 
         ProcessPendingMouseEvents(cursorDelta);
@@ -382,12 +383,11 @@ namespace AzToolsFramework
         if (m_capturingCursor)
         {
             // Reset our cursor position to the previous point
-            const QPoint screenCursorPosition = m_sourceWidget->mapToGlobal(m_previousCursorPosition);
-            AzQtComponents::SetCursorPos(screenCursorPosition);
+            AzQtComponents::SetCursorPos(m_previousGlobalCursorPosition);
         }
         else
         {
-            m_previousCursorPosition = cursorPosition;
+            m_previousGlobalCursorPosition = globalCursorPosition;
         }
     }
 

Code/Framework/AzToolsFramework/AzToolsFramework/Input/QtEventToAzInputManager.h

@@ -129,7 +129,7 @@ namespace AzToolsFramework
         // Handle mouse click events.
         void HandleMouseButtonEvent(QMouseEvent* mouseEvent);
         // Handle mouse move events.
-        void HandleMouseMoveEvent(const QPoint& cursorPosition);
+        void HandleMouseMoveEvent(const QPoint& globalCursorPosition);
         // Handles key press / release events (or ShortcutOverride events for keys listed in m_highPriorityKeys).
         void HandleKeyEvent(QKeyEvent* keyEvent);
         // Handles mouse wheel events.
@@ -156,8 +156,8 @@ namespace AzToolsFramework
         AZStd::unordered_set<Qt::Key> m_highPriorityKeys;
         // A lookup table for AZ input channel ID -> physical input channel on our mouse or keyboard device.
         AZStd::unordered_map<AzFramework::InputChannelId, AzFramework::InputChannel*> m_channels;
-        // Where the position of the mouse cursor was at the last cursor event.
-        QPoint m_previousCursorPosition;
+        // Where the mouse cursor was at the last cursor event.
+        QPoint m_previousGlobalCursorPosition;
         // The source widget to map events from, used to calculate the relative mouse position within the widget bounds.
         QWidget* m_sourceWidget;
         // Flags whether or not Qt events should currently be processed.