Monogame-Extended/source/MonoGame.Extended/Tilemaps/TilemapTileAnimation.cs

using System;

namespace MonoGame.Extended.Tilemaps
{
    /// <summary>
    /// Represents a frame-based animation for a tile.
    /// </summary>
    public class TilemapTileAnimation
    {
        private int _currentFrameIndex;
        private float _elapsedTime;

        /// <summary>
        /// Gets the animation frames.
        /// </summary>
        public TilemapTileAnimationFrame[] Frames { get; }

        /// <summary>
        /// Gets the total duration of the animation in seconds.
        /// </summary>
        public float TotalDuration
        {
            get
            {
                float total = 0;
                foreach (var frame in Frames)
                {
                    total += frame.Duration;
                }
                return total;
            }
        }

        /// <summary>
        /// Gets the current frame index.
        /// </summary>
        public int CurrentFrameIndex
        {
            get
            {
                return _currentFrameIndex;
            }
        }

        /// <summary>
        /// Gets the current frame.
        /// </summary>
        public TilemapTileAnimationFrame CurrentFrame
        {
            get
            {
                return Frames[_currentFrameIndex];
            }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="TilemapTileAnimation"/> class.
        /// </summary>
        /// <param name="frames">The animation frames.</param>
        public TilemapTileAnimation(TilemapTileAnimationFrame[] frames)
        {
            Frames = frames;
        }

        /// <summary>
        /// Updates the animation.
        /// </summary>
        /// <param name="deltaTime">The time elapsed since the last update, in seconds.</param>
        public void Update(float deltaTime)
        {
            if (Frames.Length == 0)
            {
                return;
            }

            _elapsedTime += deltaTime;

            // Advance frames based on elapsed time
            while (_elapsedTime >= Frames[_currentFrameIndex].Duration)
            {
                _elapsedTime -= Frames[_currentFrameIndex].Duration;
                _currentFrameIndex = (_currentFrameIndex + 1) % Frames.Length;
            }
        }

        public TilemapTileAnimationFrame GetFrameAtTime(float time)
        {
            if (Frames.Length == 0)
            {
                throw new InvalidOperationException("Animation has no frames");
            }

            // Wrap time within total duration
            float totalDuration = TotalDuration;
            if (totalDuration <= 0)
            {
                return Frames[0];
            }

            time = time % totalDuration;
            if (time < 0)
            {
                time += totalDuration;
            }

            // Find the frame at this time
            float accumulated = 0;
            foreach (var frame in Frames)
            {
                accumulated += frame.Duration;
                if (time < accumulated)
                {
                    return frame;
                }
            }

            // Should never reach here, but return last frame as fallback
            return Frames[Frames.Length - 1];
        }

        /// <summary>
        /// Resets the animation to the first frame.
        /// </summary>
        public void Reset()
        {
            _currentFrameIndex = 0;
            _elapsedTime = 0;
        }
    }
}