cirnogodot/Scripts/Actors/3D/PropGravityModule3D.cs

using Godot;

namespace Cirno.Scripts.Actors._3D;

public partial class PropGravityModule3D : Node
{
    [Export] public float FallingSpeed { get; private set; } = 10f;

    private StaticBody3D _parent;

    private bool _isFalling = false;
    private int _detectedBodies = 0;
    public override void _Ready()
    {
        _parent = GetParent<StaticBody3D>();
    }

    public override void _PhysicsProcess(double delta)
    {
        if (!_isFalling) return;
        _parent.GlobalPosition += new Vector3(0, FallingSpeed , 0) * (float)delta;
    }

    public void OnBodyEntered(Node3D body)
    {
        if (body == _parent) return;
        _detectedBodies++;
        TryFalling();
    }

    public void OnBodyExited(Node3D body)
    {
        if (body == _parent) return;
        _detectedBodies--;
        TryFalling();
    }

    private void TryFalling()
    {
        _isFalling = _detectedBodies == 0;
    }
}