[3d] Holding ctrl results in finer mouse wheel zooming

To match behaviour of canvas and composer

Fixes #17527

src/3d/qgscameracontroller.cpp

@@ -37,6 +37,8 @@ QgsCameraController::QgsCameraController( Qt3DCore::QNode *parent )
   , mRightMouseButtonInput( new Qt3DInput::QActionInput() )
   , mShiftAction( new Qt3DInput::QAction() )
   , mShiftInput( new Qt3DInput::QActionInput() )
+  , mCtrlAction( new Qt3DInput::QAction() )
+  , mCtrlInput( new Qt3DInput::QActionInput() )
   , mWheelAxis( new Qt3DInput::QAxis() )
   , mMouseWheelInput( new Qt3DInput::QAnalogAxisInput() )
   , mTxAxis( new Qt3DInput::QAxis() )
@@ -82,6 +84,11 @@ QgsCameraController::QgsCameraController( Qt3DCore::QNode *parent )
   mShiftInput->setSourceDevice( mKeyboardDevice );
   mShiftAction->addInput( mShiftInput );
 
+  // Keyboard ctrl
+  mCtrlInput->setButtons( QVector<int>() << Qt::Key_Control );
+  mCtrlInput->setSourceDevice( mKeyboardDevice );
+  mCtrlAction->addInput( mCtrlInput );
+
   // Keyboard Pos Tx
   mKeyboardTxPosInput->setButtons( QVector<int>() << Qt::Key_Right );
   mKeyboardTxPosInput->setScale( 1.0f );
@@ -110,6 +117,7 @@ QgsCameraController::QgsCameraController( Qt3DCore::QNode *parent )
   mLogicalDevice->addAction( mMiddleMouseButtonAction );
   mLogicalDevice->addAction( mRightMouseButtonAction );
   mLogicalDevice->addAction( mShiftAction );
+  mLogicalDevice->addAction( mCtrlAction );
   mLogicalDevice->addAxis( mWheelAxis );
   mLogicalDevice->addAxis( mTxAxis );
   mLogicalDevice->addAxis( mTyAxis );
@@ -221,7 +229,8 @@ void QgsCameraController::frameTriggered( float dt )
   int dy = mMousePos.y() - mLastMousePos.y();
   mLastMousePos = mMousePos;
 
-  mCameraData.dist -= mCameraData.dist * mWheelAxis->value() * 10 * dt;
+  double scaling = ( mCtrlAction->isActive() ? 0.1 : 1.0 );
+  mCameraData.dist -= scaling * mCameraData.dist * mWheelAxis->value() * 10 * dt;
 
   if ( mRightMouseButtonAction->isActive() )
   {

src/3d/qgscameracontroller.h

@@ -158,6 +158,9 @@ class _3D_EXPORT QgsCameraController : public Qt3DCore::QEntity
     Qt3DInput::QAction *mShiftAction = nullptr;
     Qt3DInput::QActionInput *mShiftInput = nullptr;
 
+    Qt3DInput::QAction *mCtrlAction = nullptr;
+    Qt3DInput::QActionInput *mCtrlInput = nullptr;
+
     Qt3DInput::QAxis *mWheelAxis = nullptr;
     Qt3DInput::QAnalogAxisInput *mMouseWheelInput = nullptr;