CharacterController2D - partial class - Drop-through one way platforms

CharacterController2DDropThroughOneWay.cs

using UnityEngine;

/// <summary>
/// Extends the functionality of CharacterController2D to allow down jumps through one way platforms.
/// </summary>
public partial class CharacterController2D
{
    /// <summary>
    /// Stores a value indicating whether if this Controller should heed one way platforms
    /// </summary>
    [SerializeField]
    private bool _oneWayPlatformsActive = true;

    /// <summary>
    /// Stores nominal value for platform mask
    /// </summary>
    private LayerMask _platformMaskNominal = 0;

    /// <summary>
    /// Stores nominal value for one way platform mask
    /// </summary>
    private LayerMask _oneWayPlatformMaskNominal = 0;


    /// <summary>
    /// Gets or sets a value indicating whether if this Controller should heed one way platforms
    /// </summary>
    public bool OneWayPlatformsActive
    {
        get
        {
            return _oneWayPlatformsActive;
        }
        set
        {
            _oneWayPlatformsActive = value;
            UpdatePlatformMasks();
        }
    }


    /// <summary>
    /// Update platform masks to reflect current state of areOneWayPlatformsActive
    /// </summary>
    public void UpdatePlatformMasks()
    {
        if (OneWayPlatformsActive)
        {
            platformMask = _oneWayPlatformMaskNominal | _platformMaskNominal;
        }
        else
        {
            platformMask = _platformMaskNominal;
        }
    }

    /// <summary>
    /// Saves current value of platform masks as nominal values (replaces old nominal values)
    /// </summary>
    public void SavePlatformMasks()
    {
        _platformMaskNominal = platformMask;
        _oneWayPlatformMaskNominal = oneWayPlatformMask;
    }

}

/*
    SETUP NOTES:
  
    Some changes are required to CharacterController2D:
 
        1. add keyword 'partial' to class declaration
 
        2. add this line to Awake():
            SavePlatformMasks()

    USAGE NOTES:
 
    Allow drop-though:
        OneWayPlatformsActive = false;

    Disable drop-though:
        OneWayPlatformsActive = true;
 */