Syntriax.Engine/Engine.Core/Abstract/ITransform.cs

using System;
using System.Collections.Generic;

namespace Syntriax.Engine.Core.Abstract;

/// <summary>
/// Represents the transformation properties of an object such as position, scale, and rotation.
/// </summary>
public interface ITransform : IAssignableGameObject, IEnumerable<ITransform>
{
    /// <summary>
    /// Event triggered when the <see cref="Position"/> of the <see cref="ITransform"/> changes.
    /// </summary>
    event OnPositionChangedDelegate? OnPositionChanged;

    /// <summary>
    /// Event triggered when the <see cref="Scale"/> of the <see cref="ITransform"/> changes.
    /// </summary>
    event OnScaleChangedDelegate? OnScaleChanged;

    /// <summary>
    /// Event triggered when the <see cref="Rotation"/> of the <see cref="ITransform"/> changes.
    /// </summary>
    event OnRotationChangedDelegate? OnRotationChanged;

    /// <summary>
    /// Event triggered when the <see cref="Parent"/> of the <see cref="ITransform"/> changes. The second parameter is the old <see cref="ITransform"/>.
    /// </summary>
    event OnParentChangedDelegate? OnParentChanged;

    /// <summary>
    /// Event triggered when a new <see cref="ITransform"/> is added to the <see cref="Children"/>.
    /// </summary>
    event OnChildrenAddedDelegate? OnChildrenAdded;

    /// <summary>
    /// Event triggered when an <see cref="ITransform"/> is removed from the <see cref="Children"/>.
    /// </summary>
    event OnChildrenRemovedDelegate? OnChildrenRemoved;

    /// <summary>
    /// The world position of the <see cref="ITransform"/> in 2D space.
    /// </summary>
    Vector2D Position { get; set; }

    /// <summary>
    /// The world scale of the <see cref="ITransform"/>.
    /// </summary>
    Vector2D Scale { get; set; }

    /// <summary>
    /// The world rotation of the <see cref="ITransform"/> in degrees.
    /// </summary>
    float Rotation { get; set; }

    /// <summary>
    /// The local position of the <see cref="ITransform"/> in 2D space.
    /// </summary>
    Vector2D LocalPosition { get; set; }

    /// <summary>
    /// The local scale of the <see cref="ITransform"/>.
    /// </summary>
    Vector2D LocalScale { get; set; }

    /// <summary>
    /// The local rotation of the <see cref="ITransform"/> in degrees.
    /// </summary>
    float LocalRotation { get; set; }

    /// <summary>
    /// The parent <see cref="ITransform"/> of the <see cref="ITransform"/>.
    /// </summary>
    ITransform? Parent { get; }

    /// <summary>
    /// The <see cref="ITransform"/>s that have this <see cref="ITransform"/> as their <see cref="Parent"/>.
    /// </summary>
    IReadOnlyList<ITransform> Children { get; }

    /// <summary>
    /// Sets the parent <see cref="ITransform"/> of this <see cref="ITransform"/>.
    /// </summary>
    /// <param name="transform">The parent <see cref="ITransform"/> to set.</param>
    void SetParent(ITransform? transform);

    /// <summary>
    /// Adds a child <see cref="ITransform"/> to this <see cref="ITransform"/>.
    /// </summary>
    /// <param name="transform">The child <see cref="ITransform"/> to add.</param>
    void AddChild(ITransform transform);

    /// <summary>
    /// Removes a child <see cref="ITransform"/> from this <see cref="ITransform"/>.
    /// </summary>
    /// <param name="transform">The child <see cref="ITransform"/> to remove.</param>
    void RemoveChild(ITransform transform);

    delegate void OnPositionChangedDelegate(ITransform sender);
    delegate void OnScaleChangedDelegate(ITransform sender);
    delegate void OnRotationChangedDelegate(ITransform sender);
    delegate void OnParentChangedDelegate(ITransform sender, ITransform? newParent);
    delegate void OnChildrenAddedDelegate(ITransform sender, ITransform childrenAdded);
    delegate void OnChildrenRemovedDelegate(ITransform sender, ITransform childrenRemoved);
}