using System;
using UnityEngine;

namespace UnityStandardAssets.ImageEffects
{
	[ExecuteInEditMode]
	[RequireComponent(typeof(Camera))]
	[AddComponentMenu("Image Effects/Rendering/Global Fog")]
	public class GlobalFog : PostEffectsBase
	{
		[Tooltip("Apply distance-based fog?")]
		public bool distanceFog = true;

		[Tooltip("Exclude far plane pixels from distance-based fog? (Skybox or clear color)")]
		public bool excludeFarPixels = true;

		[Tooltip("Distance fog is based on radial distance from camera when checked")]
		public bool useRadialDistance;

		[Tooltip("Apply height-based fog?")]
		public bool heightFog = true;

		[Tooltip("Fog top Y coordinate")]
		public float height = 1f;

		[Range(0.001f, 10f)]
		public float heightDensity = 2f;

		[Tooltip("Push fog away from the camera by this amount")]
		public float startDistance;

		public Shader fogShader;

		private Material fogMaterial;

		public override bool CheckResources()
		{
			CheckSupport(true);
			fogMaterial = CheckShaderAndCreateMaterial(fogShader, fogMaterial);
			if (!isSupported)
			{
				ReportAutoDisable();
			}
			return isSupported;
		}

		[ImageEffectOpaque]
		private void OnRenderImage(RenderTexture source, RenderTexture destination)
		{
			if (!CheckResources() || (!distanceFog && !heightFog))
			{
				Graphics.Blit(source, destination);
				return;
			}
			Camera component = GetComponent<Camera>();
			Transform transform = component.transform;
			float nearClipPlane = component.nearClipPlane;
			float farClipPlane = component.farClipPlane;
			float fieldOfView = component.fieldOfView;
			float aspect = component.aspect;
			Matrix4x4 identity = Matrix4x4.identity;
			float num = fieldOfView * 0.5f;
			Vector3 vector = transform.right * nearClipPlane * Mathf.Tan(num * ((float)Math.PI / 180f)) * aspect;
			Vector3 vector2 = transform.up * nearClipPlane * Mathf.Tan(num * ((float)Math.PI / 180f));
			Vector3 vector3 = transform.forward * nearClipPlane - vector + vector2;
			float num2 = vector3.magnitude * farClipPlane / nearClipPlane;
			vector3.Normalize();
			vector3 *= num2;
			Vector3 vector4 = transform.forward * nearClipPlane + vector + vector2;
			vector4.Normalize();
			vector4 *= num2;
			Vector3 vector5 = transform.forward * nearClipPlane + vector - vector2;
			vector5.Normalize();
			vector5 *= num2;
			Vector3 vector6 = transform.forward * nearClipPlane - vector - vector2;
			vector6.Normalize();
			vector6 *= num2;
			identity.SetRow(0, vector3);
			identity.SetRow(1, vector4);
			identity.SetRow(2, vector5);
			identity.SetRow(3, vector6);
			Vector3 position = transform.position;
			float num3 = position.y - height;
			float z = ((!(num3 <= 0f)) ? 0f : 1f);
			float y = ((!excludeFarPixels) ? 2f : 1f);
			fogMaterial.SetMatrix("_FrustumCornersWS", identity);
			fogMaterial.SetVector("_CameraWS", position);
			fogMaterial.SetVector("_HeightParams", new Vector4(height, num3, z, heightDensity * 0.5f));
			fogMaterial.SetVector("_DistanceParams", new Vector4(0f - Mathf.Max(startDistance, 0f), y, 0f, 0f));
			FogMode fogMode = RenderSettings.fogMode;
			float fogDensity = RenderSettings.fogDensity;
			float fogStartDistance = RenderSettings.fogStartDistance;
			float fogEndDistance = RenderSettings.fogEndDistance;
			bool flag = fogMode == FogMode.Linear;
			float num4 = ((!flag) ? 0f : (fogEndDistance - fogStartDistance));
			float num5 = ((!(Mathf.Abs(num4) > 0.0001f)) ? 0f : (1f / num4));
			Vector4 value = default(Vector4);
			value.x = fogDensity * 1.2011224f;
			value.y = fogDensity * 1.442695f;
			value.z = ((!flag) ? 0f : (0f - num5));
			value.w = ((!flag) ? 0f : (fogEndDistance * num5));
			fogMaterial.SetVector("_SceneFogParams", value);
			fogMaterial.SetVector("_SceneFogMode", new Vector4((float)fogMode, useRadialDistance ? 1 : 0, 0f, 0f));
			int num6 = 0;
			CustomGraphicsBlit(passNr: (!distanceFog || !heightFog) ? (distanceFog ? 1 : 2) : 0, source: source, dest: destination, fxMaterial: fogMaterial);
		}

		private static void CustomGraphicsBlit(RenderTexture source, RenderTexture dest, Material fxMaterial, int passNr)
		{
			RenderTexture.active = dest;
			fxMaterial.SetTexture("_MainTex", source);
			GL.PushMatrix();
			GL.LoadOrtho();
			fxMaterial.SetPass(passNr);
			GL.Begin(7);
			GL.MultiTexCoord2(0, 0f, 0f);
			GL.Vertex3(0f, 0f, 3f);
			GL.MultiTexCoord2(0, 1f, 0f);
			GL.Vertex3(1f, 0f, 2f);
			GL.MultiTexCoord2(0, 1f, 1f);
			GL.Vertex3(1f, 1f, 1f);
			GL.MultiTexCoord2(0, 0f, 1f);
			GL.Vertex3(0f, 1f, 0f);
			GL.End();
			GL.PopMatrix();
		}
	}
}