using UnityEngine;

namespace UltimateWater.Internal
{
	public sealed class PixelShaderFFT : GpuFFT
	{
		private TemporaryRenderTexture _RT1;

		private TemporaryRenderTexture _RT2;

		private readonly Material _Material;

		public PixelShaderFFT(Shader fftShader, int resolution, bool highPrecision, bool twoChannels)
			: base(resolution, highPrecision, twoChannels, false)
		{
			_Material = new Material(fftShader)
			{
				hideFlags = HideFlags.DontSave
			};
		}

		public override void Dispose()
		{
			base.Dispose();
			if (_Material == null)
			{
				Object.Destroy(_Material);
			}
		}

		public override void SetupMaterials()
		{
			_Material.SetTexture(ShaderVariables.ButterflyTex, base.Butterfly);
		}

		public override void ComputeFFT(Texture tex, RenderTexture target)
		{
			using (_RT1 = _RenderTexturesSet.GetTemporary())
			{
				using (_RT2 = _RenderTexturesSet.GetTemporary())
				{
					ComputeFFT(tex, null, _TwoChannels ? 2 : 0);
					ComputeFFT((RenderTexture)_RT1, target, (!_TwoChannels) ? 1 : 3);
				}
			}
		}

		private void ComputeFFT(Texture tex, RenderTexture target, int passIndex)
		{
			_Material.SetFloat(ShaderVariables.ButterflyPass, 0.5f / (float)_NumButterfliesPow2);
			Graphics.Blit(tex, _RT2, _Material, passIndex);
			SwapRT();
			for (int i = 1; i < _NumButterflies; i++)
			{
				if (target != null && i == _NumButterflies - 1)
				{
					_Material.SetFloat(ShaderVariables.ButterflyPass, ((float)i + 0.5f) / (float)_NumButterfliesPow2);
					Graphics.Blit((RenderTexture)_RT1, target, _Material, (passIndex != 1) ? 5 : 4);
				}
				else
				{
					_Material.SetFloat(ShaderVariables.ButterflyPass, ((float)i + 0.5f) / (float)_NumButterfliesPow2);
					Graphics.Blit((RenderTexture)_RT1, _RT2, _Material, passIndex);
				}
				SwapRT();
			}
		}

		private void SwapRT()
		{
			TemporaryRenderTexture rT = _RT1;
			_RT1 = _RT2;
			_RT2 = rT;
		}
	}
}