Godot 3 C#: browser-like touchscreen camera controller

TouchCamera2D.cs

using Godot;

// Touch controls for the camera.
// Use two fingers to pan or zoom.
public class TouchCamera2D : Camera2D
{
    [Export] public float MinZoom = 0.25f;
    [Export] public float MaxZoom = 4.0f;

    // All of these are in screen space.
    // They can be scaled by Zoom to get them in world space.
    Vector2 LastTouchPoint_0, LastTouchPoint_1;
    float LastPinchDistance;
    Vector2 LastPinchMidpoint;

    bool IsTouching_0, IsTouching_1;
    bool TwoFingersTouching => IsTouching_0 && IsTouching_1;
    bool LastPinchDataIsValid;

    // Like Camera2D.Zoom, 0.25 means 4x zoom in, 4.0 means 4x zoom out.
    new float Zoom
    {
        get => base.Zoom.x;
        set
        {
            var zoom = Mathf.Clamp(value, MinZoom, MaxZoom);
            base.Zoom = new Vector2(zoom, zoom);
        }
    }

    float GetPinchDistance() => LastTouchPoint_0.DistanceTo(LastTouchPoint_1);
    Vector2 GetPinchMidpoint() => (LastTouchPoint_0 + LastTouchPoint_1) / 2f;


    public override void _UnhandledInput(InputEvent @event)
    {
        // The touch event is fired when a new finger comes into contact, or ends contact, with the screen.
        // The drag event is fired when a finger which is already down moves.

        if (@event is InputEventScreenTouch touch)
            HandleTouch(touch);
        if (@event is InputEventScreenDrag drag)
            HandleDrag(drag);
    }

    void HandleTouch(InputEventScreenTouch touchEvent)
    {
        if (touchEvent.Index == 0)
        {
            LastTouchPoint_0 = touchEvent.Position;
            IsTouching_0 = touchEvent.Pressed;
        }
        if (touchEvent.Index == 1)
        {
            LastTouchPoint_1 = touchEvent.Position;
            IsTouching_1 = touchEvent.Pressed;
        }

        if (TwoFingersTouching)
        {
            LastPinchDistance = GetPinchDistance();
            LastPinchMidpoint = GetPinchMidpoint();
            LastPinchDataIsValid = true;
        }
        else
        {
            LastPinchDataIsValid = false;
        }
    }

    void HandleDrag(InputEventScreenDrag touchEvent)
    {
        if (touchEvent.Index == 0)
            LastTouchPoint_0 = touchEvent.Position;
        if (touchEvent.Index == 1)
            LastTouchPoint_1 = touchEvent.Position;

        if (!TwoFingersTouching || !LastPinchDataIsValid)
            return;

        var currentPinchDistance = GetPinchDistance();
        var currentMidpoint = GetPinchMidpoint();

        // Handle zoom
        {
            float viewportWidthPixels = GetViewportRect().Size.x;

            // These three variables are all measured in worldspace.
            float distanceToZoom = (LastPinchDistance - currentPinchDistance) * Zoom;
            float currentViewportSize = viewportWidthPixels * Zoom;
            float targetViewportSize = currentViewportSize + distanceToZoom;

            float previousZoom = Zoom;
            Zoom = targetViewportSize / viewportWidthPixels;

            // We must add a camera position offset to account for the fact that the user is not zooming in on the exact center of the screen.
            Vector2 viewportCenter = GetViewportRect().Size / 2f;
            Vector2 pinchOffset = currentMidpoint - viewportCenter;
            Position += pinchOffset * (previousZoom - Zoom);
        }

        // Handle pan
        {
            Vector2 panDelta = (currentMidpoint - LastPinchMidpoint) * Zoom;
            Position -= panDelta;
        }

        LastPinchDistance = currentPinchDistance;
        LastPinchMidpoint = currentMidpoint;
    }
}

Browser-like touchscreen camera controls for Godot 3.

Demo:

screen-20260426-101100-censored.mp4

Notes:

• This script assumes the camera's "Anchor Mode" is "Drag Center".
• It should be easy to port this to Godot 4 or GDScript if you need to.
  • In Godot 4 they changed it from "zoom in = Camera2D.Zoom is small" to "zoom in = Camera2D.Zoom is big" so you'll have to invert the thing on line 27 or something, I'm not sure exactly. Also swap the default values for MinZoom and MaxZoom

Hope this is useful to someone :)