using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
public class NightVisionEffect : MonoBehaviour {

	#region Variables
	public Shader nightVisionShader;

	public float contrast = 2.0f;
	public float brightness = 1.0f;
	public Color nightVisionColor = Color.white;

	public Texture2D vignetteTexture;

	public Texture2D scanLineTexture;
	public float scanLineTileAmount = 4.0f;

	public Texture2D nightVisionNoise;
	public float noiseXSpeed = 100.0f;
	public float noiseYSpeed = 100.0f;

	public float distortion = 0.2f;
	public float scale = 0.8f;
	
	private Material curMaterial;
	private float randomValue = 0.0f;
	#endregion
	
	#region Properties
	public Material material {
		get {
			if (curMaterial == null) {
				curMaterial = new Material(nightVisionShader);
				curMaterial.hideFlags = HideFlags.HideAndDontSave;
			}
			return curMaterial;
		}
	}
	#endregion
	
	// Use this for initialization
	void Start () {
		if (SystemInfo.supportsImageEffects == false) {
			enabled = false;
			return;
		}
		
		if (nightVisionShader != null && nightVisionShader.isSupported == false) {
			enabled = false;
		}
	}
	
	void OnRenderImage (RenderTexture sourceTexture, RenderTexture destTexture){
		if (nightVisionShader != null) {
			material.SetFloat("_Contrast", contrast);
			material.SetFloat("_Brightness", brightness);
			material.SetColor("_NightVisionColor", nightVisionColor);
			material.SetFloat("_RandomValue", randomValue);
			material.SetFloat("_Distortion", distortion);
			material.SetFloat("_Scale", scale);

			if (vignetteTexture) {
				material.SetTexture("_VignetteTex", vignetteTexture);
			}

			if (scanLineTexture) {
				material.SetTexture("_ScanLineTex", scanLineTexture);
				material.SetFloat("_ScanLineTileAmount", scanLineTileAmount);
			}

			if (nightVisionNoise) {
				material.SetTexture("_NoiseTex", nightVisionNoise);
				material.SetFloat("_NoiseXSpeed", noiseXSpeed);
				material.SetFloat("_NoiseYSpeed", noiseYSpeed);
			}

			Graphics.Blit(sourceTexture, destTexture, material);
		} else {
			Graphics.Blit(sourceTexture, destTexture);
		}
	}
	
	// Update is called once per frame
	void Update () {
		contrast = Mathf.Clamp(contrast, 0.0f, 4.0f);
		brightness = Mathf.Clamp(brightness, 0.0f, 2.0f);
		distortion = Mathf.Clamp(distortion, -1.0f, 1.0f);
		scale = Mathf.Clamp(scale, 0.0f, 3.0f);
		randomValue = Random.Range(-1.0f, 1.0f);
	}
	
	void OnDisable () {
		if (curMaterial != null) {
			DestroyImmediate(curMaterial);
		}
	}
}

Shader "Custom/NightVisionEffectShader" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_VignetteTex ("Vignette Texture", 2D) = "white" {}
		_ScanLineTex ("Scan Line Texture", 2D) = "white" {}
		_ScanLineTileAmount ("Scale Line Tile Amount", Float) = 4.0
		_NoiseTex ("Noise Texture", 2D) = "white" {}
		_NoiseXSpeed ("Noise X Speed", Float) = 100.0
		_NoiseYSpeed ("Noise Y Speed", Float) = 100.0
		_NightVisionColor ("Night Vision Color", Color) = (1, 1, 1, 1)
		_Contrast ("Contrast", Range(0, 4)) = 2
		_Brightness ("Brightness", Range(0, 2)) = 1
		_RandomValue ("Random Value", Float) = 0
		_Distortion ("Distortion", Float) = 0.2
		_Scale ("Scale (Zoom)", Float) = 0.8
	}
	SubShader {
		Pass {
			CGPROGRAM
			
			#pragma vertex vert_img
			#pragma fragment frag
			
			#include "UnityCG.cginc"
			
			uniform sampler2D _MainTex;
			uniform sampler2D _VignetteTex;
			uniform sampler2D _ScanLineTex;
			fixed _ScanLineTileAmount;
			uniform sampler2D _NoiseTex;
			fixed _NoiseXSpeed;
			fixed _NoiseYSpeed;
			fixed4 _NightVisionColor;
			fixed _Contrast;
			fixed _Brightness;
			fixed _RandomValue;
			fixed _Distortion;
			fixed _Scale;
			
			float2 barrelDistortion(float2 coord) {
				// Lens distortion algorithm
				// See http://www.ssontech.com/content/lensalg.htm
				
				float2 h = coord.xy - float2(0.5, 0.5);
				float r2 = h.x * h.x + h.y * h.y;
				float f = 1.0 + r2 * (_Distortion * sqrt(r2));
				
				return f * _Scale * h + 0.5;
			}
			
			fixed4 frag(v2f_img i) : COLOR {
				// Get the colors from the Render Texture and the uv‘s
				// from the v2f_img struct
				half2 distortedUV = barrelDistortion(i.uv);
				fixed4 renderTex = tex2D(_MainTex, distortedUV);
				fixed4 vignetteTex = tex2D(_VignetteTex, i.uv);
				
				// Process  scan lines and noise
				half2 scanLinesUV = half2(i.uv.x * _ScanLineTileAmount, i.uv.y * _ScanLineTileAmount);
				fixed4 scanLineTex = tex2D(_ScanLineTex, scanLinesUV);
				
				half2 noiseUV = half2(i.uv.x + (_RandomValue * _SinTime.z * _NoiseXSpeed),
											i.uv.y + (_Time.x * _NoiseYSpeed));
				fixed4 noiseTex = tex2D(_NoiseTex, noiseUV);
				
				// Get the luminosity values from the render texture using the YIQ values
				fixed lum = dot(fixed3(0.299, 0.587, 0.114), renderTex.rgb);
				lum += _Brightness;
				fixed4 finalColor = (lum * 2) + _NightVisionColor;
				
				// Final output
				finalColor = pow(finalColor, _Contrast);
				finalColor *= vignetteTex;
				finalColor *= scanLineTex * noiseTex;
				
				return finalColor;
			}
			
			ENDCG
		}
	} 
	FallBack "Diffuse"
}