using UnityEngine;

namespace UltimateWater.Internal
{
	public abstract class GpuFFT
	{
		private Texture2D _Butterfly;

		protected RenderTexturesCache _RenderTexturesSet;

		protected int _Resolution;

		protected int _NumButterflies;

		protected int _NumButterfliesPow2;

		protected bool _TwoChannels;

		private readonly bool _HighPrecision;

		private readonly bool _UsesUav;

		public Texture2D Butterfly => _Butterfly;

		public int Resolution => _Resolution;

		public abstract void SetupMaterials();

		public abstract void ComputeFFT(Texture tex, RenderTexture target);

		public virtual void Dispose()
		{
			if (_Butterfly != null)
			{
				_Butterfly.Destroy();
				_Butterfly = null;
			}
		}

		private void CreateTextures()
		{
			CreateButterflyTexture();
		}

		private void RetrieveRenderTexturesSet()
		{
			RenderTextureFormat format = ((!_TwoChannels) ? (_HighPrecision ? RenderTextureFormat.RGFloat : RenderTextureFormat.RGHalf) : (_HighPrecision ? RenderTextureFormat.ARGBFloat : RenderTextureFormat.ARGBHalf));
			_RenderTexturesSet = RenderTexturesCache.GetCache(_Resolution << 1, _Resolution << 1, 0, format, linear: true, _UsesUav);
		}

		protected virtual void FillButterflyTexture(Texture2D butterfly, int[][] indices, Vector2[][] weights)
		{
			float num = _Resolution << 1;
			Color color = default(Color);
			for (int i = 0; i < _NumButterflies; i++)
			{
				for (int j = 0; j < 2; j++)
				{
					int num2 = ((j != 0) ? _Resolution : 0);
					for (int k = 0; k < _Resolution; k++)
					{
						int num3 = _NumButterflies - i - 1;
						int num4 = k << 1;
						color.r = ((float)(indices[num3][num4] + num2) + 0.5f) / num;
						color.g = ((float)(indices[num3][num4 + 1] + num2) + 0.5f) / num;
						color.b = weights[i][k].x;
						color.a = weights[i][k].y;
						butterfly.SetPixel(num2 + k, i, color);
					}
				}
			}
		}

		private void CreateButterflyTexture()
		{
			_Butterfly = new Texture2D(_Resolution << 1, _NumButterfliesPow2, _HighPrecision ? TextureFormat.RGBAFloat : TextureFormat.RGBAHalf, mipChain: false, linear: true)
			{
				hideFlags = HideFlags.DontSave,
				filterMode = FilterMode.Point,
				wrapMode = TextureWrapMode.Clamp
			};
			ButterflyFFTUtility.ComputeButterfly(_Resolution, _NumButterflies, out int[][] indices, out Vector2[][] weights);
			FillButterflyTexture(_Butterfly, indices, weights);
			_Butterfly.Apply();
		}

		protected GpuFFT(int resolution, bool highPrecision, bool twoChannels, bool usesUAV)
		{
			_Resolution = resolution;
			_HighPrecision = highPrecision;
			_NumButterflies = (int)(Mathf.Log(resolution) / Mathf.Log(2f));
			_NumButterfliesPow2 = Mathf.NextPowerOfTwo(_NumButterflies);
			_TwoChannels = twoChannels;
			_UsesUav = usesUAV;
			RetrieveRenderTexturesSet();
			CreateTextures();
		}
	}
}