EarthquakeEffect.cs

using System.Drawing;
using Gondwana.Physics.Movement.Easing;
using Gondwana.Rendering.Views;
 
namespace Gondwana.Effects;

public sealed class EarthquakeEffect : DisplayEffect
{
    private readonly Random _random;
    private PointF _originalFactor;
    private PointF _originalPixels;

    public EarthquakeEffect(
        float durationSeconds,
        float intensityPx = 8f,
        bool decay = true,
        int? randomSeed = null)
        : base(durationSeconds, EasingKind.Linear)
    {
        if (intensityPx < 0f)
            throw new ArgumentOutOfRangeException(nameof(intensityPx));
 
        IntensityPx = intensityPx;
        Decay = decay;
        _random = new Random(randomSeed ?? Random.Shared.Next());
    }

    public float IntensityPx { get; }

    public bool Decay { get; }
 
    internal override EffectChannel Channel => EffectChannel.Transform;
 
    internal override bool SupportsTarget(object target) => target is View;

    private protected override void OnStarting()
    {
        _originalFactor = EffectTargetAccess.GetOffsetFactor(Target);
        _originalPixels = EffectTargetAccess.GetOffsetPixels(Target);
    }

    private protected override void ApplyProgress(float progress)
    {
        if (progress >= 1f || IntensityPx <= 0f)
        {
            EffectTargetAccess.SetTransform(
                Target,
                _originalFactor,
                _originalPixels);
 
            return;
        }
 
        float amplitude = Decay
            ? IntensityPx * (1f - progress)
            : IntensityPx;
 
        float x = ((float)_random.NextDouble() * 2f - 1f) * amplitude;
        float y = ((float)_random.NextDouble() * 2f - 1f) * amplitude;
 
        EffectTargetAccess.SetTransform(
            Target,
            _originalFactor,
            new PointF(
                _originalPixels.X + x,
                _originalPixels.Y + y));
    }

    private protected override void RestoreOriginalState() =>
        EffectTargetAccess.SetTransform(Target, _originalFactor, _originalPixels);
}