← Back to Game Dev Log
March 20, 2024•6 min read

Implementing Smooth Camera Zoom in Unreal Engine 5

A detailed breakdown of implementing zoom in/out functionality with smooth transitions using curves and input actions.

Unreal Engine 5BlueprintsCamera SystemRTSGame Development

Implementing Smooth Camera Zoom in Unreal Engine 5


Building on my RTS camera system, I've successfully implemented smooth zoom in and out functionality. This feature is crucial for RTS games, allowing players to get both tactical close-up views and strategic overviews of the battlefield.


Input System Setup


The foundation of the zoom system starts with proper input configuration:


Input Actions Created

  • **IA_ZoomIn**: Digital Bool action for zooming in
  • **IA_ZoomOut**: Digital Bool action for zooming out
  • **IA_ZoomReset**: Digital Bool action for resetting zoom to default
  • **LeftCtrlModifier**: Digital Bool modifier for chorded actions

    • Input Mapping

    All actions are mapped through the IMC_CameraMove input mapping context, with the reset action configured as a chorded action using the LeftCtrlModifier for intuitive control.


    Smooth Zoom with Curve Assets


    To achieve natural-feeling zoom transitions, I created a Float Curve asset:


    Curve Configuration

  • **Key Points**: (0, 1350) and (1, 300)
  • **Curve Type**: Cubic with flat tangents
  • **Purpose**: Maps zoom input (0-1) to camera arm length (300-1350)

    • This curve provides smooth interpolation between zoom levels, avoiding the jarring linear transitions that can make camera movement feel robotic.


    Blueprint Implementation


    BP_TopDownCamera

    The camera blueprint contains the core zoom logic:


    SetArmLength(float ZoomAmount)

  • Uses the CurveZoomLength to evaluate the zoom amount
  • Applies the result to the Camera Boom's Target Arm Length
  • This creates the actual zoom effect by adjusting the camera distance

    • BP_PawnMovementComp

    The movement component handles zoom state management:


    ZoomIn()

  • Increments DeltaZoomAmount using Lerp for smooth transitions
  • Updates the ZoomAmount variable
  • Calls SetArmLength on the CameraPawnRef with the new value

    • ZoomOut()

  • Decrements DeltaZoomAmount using Lerp
  • Updates ZoomAmount
  • Calls SetArmLength similarly

    • ResetZoom()

  • Resets DeltaZoomAmount to 0.5 (the midpoint of our curve)
  • Provides a quick way to return to the default view

    • ZoomEvents()

  • Centralized function called each tick
  • Applies the current zoom state
  • Designed to handle future camera features like panning and POV changes

    • Player Controller Integration


    The BP_PlayerController maps the input actions to their respective functions:

  • IA_ZoomIn → ZoomIn()
  • IA_ZoomOut → ZoomOut()
  • IA_ZoomReset → ResetZoom()

    • This creates a clean separation between input handling and camera logic.


    Runtime Updates


    The system calls ZoomEvents() from the Event Tick in BP_PawnMovementComp, ensuring that zoom changes are applied in real-time. This approach allows for smooth, responsive camera control that feels natural to players.


    Technical Benefits


    This implementation provides several advantages:

  • **Smooth Transitions**: The curve-based approach eliminates jarring camera movements
  • **Scalable Design**: The centralized ZoomEvents function can easily accommodate additional camera features
  • **Performance Optimized**: Efficient updates that don't impact frame rate
  • **User-Friendly**: Intuitive controls with reset functionality

    • Future Enhancements


    With this foundation in place, I'm planning to add:

  • Zoom speed customization
  • Zoom bounds based on map size
  • Smooth camera panning
  • Camera rotation around focal points

    • This zoom system forms a solid foundation for the complete RTS camera experience!