FoodFactory/RTSCamera.cs

using Godot;
using System;
using SJK.Math;
using Chickensoft.SaveFileBuilder;
using Chickensoft.Introspection;
using Chickensoft.Serialization;


[Meta, Id("save_data")]
public partial class SaveData
{
  [Save("player_transform")]
  public Transform3D Transform3D {get;set;}
  [Save("player_camera")]
  public Transform3D CameraTransform {get;set;}
}
public partial class RTSCamera : Node3D, ISaveable<SaveData>
{
  [Export]
  public Camera3D camera;
  Vector3 positionStartPos;
  Vector3 positionOffsetPos;
  Vector3 lastTransalation;

  Vector3 cameraTargetOffset;
  Action Update_CurrentFunc;

  //Generic bookkeeping variables;
  Vector2 LastMousePostition;
  //Camera Dragging Bookkeeping variables
  Vector3 LastMouseGroundPlanePositon;
  //Camera Rotating Bookkeeping variables
  float CameraRotateSpeed = .5f;
  bool isDraging;
  public override void _Ready()
  {
    Update_CurrentFunc = Update_DetectModeStart;
  }
  void Update_DetectModeStart()
  {
    if (Input.IsActionJustPressed("move_mouse"))
    {
      //Mouse Left went Down
      //Does nothing basicly
    }
    else if (Input.IsActionPressed("move_mouse") && GetViewport().GetMousePosition() != LastMousePostition)
    {
      LastMouseGroundPlanePositon = camera.MouseToGroundPlane() ?? Vector3.Zero;
      Update_CurrentFunc = Update_CameraDrag;
      Update_CurrentFunc();
      // GD.Print("1");
    }
    else if (Input.IsActionPressed("camera_rotate") && GetViewport().GetMousePosition() != LastMousePostition)
    {
      LastMouseGroundPlanePositon = camera.MouseToGroundPlane() ?? Vector3.Zero;
      Update_CurrentFunc = Update_RotateCamera;
      Update_CurrentFunc();
      // GD.Print("2");
    }

  }
  public override void _Process(double delta)
  {
    if (Input.IsActionJustPressed("ui_cancel"))
    {
      CancelUpdateFunc();
    }
    // GD.PrintS(positionStartPos,positionOffsetPos,lastTransalation,LastMouseGroundPlanePositon,LastMousePostition,cameraTargetOffset,scrollAmount);
    Update_CurrentFunc();
    Update_CameraScroll((float)delta);
    LastMousePostition = GetViewport().GetMousePosition();
    camera.Fov = Mathf.Lerp(camera.Fov, Mathf.Lerp(90, 50, (camera.Position.Y - 5) / (80 - 5)), (float)delta * 10);
  }
  void CancelUpdateFunc()
  {
    Update_CurrentFunc = Update_DetectModeStart;
  }
  void Update_CameraDrag()
  {
    if (Input.IsActionJustReleased("move_mouse"))
    {
      CancelUpdateFunc();
    }

    var hitpos = camera.MouseToGroundPlane() ?? Vector3.Zero;


    var diff = LastMouseGroundPlanePositon - hitpos;

    GlobalTranslate(diff);
    LastMouseGroundPlanePositon = hitpos = camera.MouseToGroundPlane() ?? Vector3.Zero;

  }
  float scrollAmount;
  public override void _UnhandledInput(InputEvent @event)
  {
    scrollAmount += Input.IsActionJustReleased("mouse_scroll_up") ? 1 : 0;
    scrollAmount += Input.IsActionJustReleased("mouse_scroll_down") ? -1 : 0;
    if (@event is InputEventKey eventKey && eventKey.Keycode == Key.F)
    {
      GlobalPosition = Vector3.Zero;
      camera.Position = Vector3.Zero;
      CancelUpdateFunc();
    }
  }
  void Update_CameraScroll(float delta)
  {

    // Zoom to scrollwheel
    // float scrollAmount = Input.IsActionJustReleased("mouse_scroll_up")?1:0;
    // scrollAmount += Input.IsActionJustReleased( "mouse_scroll_down")?-1:0;
    // GD.Print(scrollAmount);
    float minHeight = 2;
    float maxHeight = 30;
    // Move camera towards hitPos
    // var hitPos = camera.MouseToGroundPlane();
    // Vector3 dir = hitPos - camera.Translation;
    var dir = -camera.GlobalTransform.Basis.Z * .5f;

    var p = camera.Position;

    // Stop zooming out at a certain distance.
    // TODO: Maybe you should still slide around at 20 zoom?
    if (scrollAmount > 0 || p.Y < (maxHeight - 0.1f))
    {
      cameraTargetOffset += dir * scrollAmount;
    }
    // DebugDraw3D.DrawArrow(Vector3.Zero,cameraTargetOffset);
    Vector3 lastCameraPosition = camera.Position;
    camera.Position = camera.Position.Lerp(camera.Position + cameraTargetOffset, delta);
    cameraTargetOffset -= camera.Position - lastCameraPosition;

    p = camera.Position;
    if (p.Y < minHeight)
    {
      p.Y = minHeight;
    }
    if (p.Y > maxHeight)
    {
      p.Y = maxHeight;
    }

    camera.Position = p;
    // Change camera angle
    camera.RotationDegrees = new Vector3(
        Mathf.Lerp(-50, -75, camera.Position.Y / maxHeight),
        camera.RotationDegrees.Y,
        camera.RotationDegrees.Z
    );
    scrollAmount = 0;
  }
  void Update_RotateCamera()
  {
    if (!Input.IsActionPressed("move_mouse"))
    {
      CancelUpdateFunc();
    }
    Vector2 hitpos = GetViewport().GetMousePosition();

    Vector2 diff = LastMousePostition - hitpos;
    camera.RotationDegrees = new Vector3(
        camera.RotationDegrees.X,
        camera.RotationDegrees.Y + (diff.X * CameraRotateSpeed),
        camera.RotationDegrees.Z
    );
    LastMousePostition = hitpos = GetViewport().GetMousePosition();
  }

  public SaveData Save() => new(){Transform3D = Transform, CameraTransform = camera.Transform};
  public void Load(in SaveData data)
  {
    Transform = data.Transform3D;
    camera.Transform = data.CameraTransform;
  }
}

public static partial class SJKMath
{
  public static Vector3? MouseToPlane(this Plane plane, Camera3D viewCamera, Vector2? mousePos = null)
  {
    var from = viewCamera.ProjectRayOrigin( mousePos ?? viewCamera.GetViewport().GetMousePosition());
    var normal = viewCamera.ProjectRayNormal(mousePos ?? viewCamera.GetViewport().GetMousePosition());
    return plane.IntersectsRay(from, normal);
  }
  public static Vector3? MouseToGroundPlane(this Camera3D viewCamera, Vector2? mousePos = null, float offset = 0) =>
    (Plane.PlaneXZ with { D = offset }).MouseToPlane(viewCamera, mousePos);
}