using UnityEngine;

using System.Collections;

[RequireComponent(typeof(UITexture))]

public class BlurTextureMaker : MonoBehaviour {

	public int iterations = 3;

	public float blurSpread = 0.6f;

	public Shader blurShader = null;

	static Material m_Material = null;

	public Camera camera;

	private UITexture mTexture;

	private RenderTexture mRT;

	protected Material material

	{

		get

		{

			if (m_Material == null)

			{

				m_Material = new Material(blurShader);

				m_Material.hideFlags = HideFlags.DontSave;

			}

			return m_Material;

		}

	}

	protected void Awake()

	{

		mTexture = GetComponent<UITexture>();

	}

	protected void Start()

	{

		// Disable if we don't support image effects

		if (!SystemInfo.supportsImageEffects)

		{

			enabled = false;

			return;

		}

		// Disable if the shader can't run on the users graphics card

		if (!blurShader || !material.shader.isSupported)

		{

			enabled = false;

			return;

		}

		int rtWidth = (int)(NGUITools.screenSize.x / 4);

		int rtHeight = (int)(NGUITools.screenSize.y / 4);

		mRT = RenderTexture.GetTemporary(rtWidth, rtHeight, 0, RenderTextureFormat.Default);

		mTexture.mainTexture = Generate();

	}

	protected void OnDestroy()

	{

		if (null != mRT)

		{

			RenderTexture.ReleaseTemporary(mRT);

		}

	}

	// Performs one blur iteration.

	public void FourTapCone(RenderTexture source, RenderTexture dest, int iteration)

	{

		float off = 0.5f + iteration * blurSpread;

		Graphics.BlitMultiTap(source, dest, material,

			new Vector2(-off, -off),

			new Vector2(-off, off),

			new Vector2(off, off),

			new Vector2(off, -off)

		);

	}

	// Downsamples the texture to a quarter resolution.

	private void DownSample4x(RenderTexture source, RenderTexture dest)

	{

		float off = 1.0f;

		Graphics.BlitMultiTap(source, dest, material,

			new Vector2(-off, -off),

			new Vector2(-off, off),

			new Vector2(off, off),

			new Vector2(off, -off)

		);

	}

	// Called by the camera to apply the image effect

	void RenderImage(RenderTexture source, RenderTexture destination)

	{

		int rtW = source.width / 4;

		int rtH = source.height / 4;

		RenderTexture buffer = RenderTexture.GetTemporary(rtW, rtH, 0);

		// Copy source to the 4x4 smaller texture.

		DownSample4x(source, buffer);

		// Blur the small texture

		for (int i = 0; i < iterations; i++)

		{

			RenderTexture buffer2 = RenderTexture.GetTemporary(rtW, rtH, 0);

			FourTapCone(buffer, buffer2, i);

			RenderTexture.ReleaseTemporary(buffer);

			buffer = buffer2;

		}

		Graphics.Blit(buffer, destination);

		RenderTexture.ReleaseTemporary(buffer);

	}

	public RenderTexture Generate()

	{

		int rtWidth = (int) (NGUITools.screenSize.x/4);

        int rtHeight = (int) (NGUITools.screenSize.y/4);

		var tex = RenderTexture.GetTemporary(rtWidth, rtHeight, 0, RenderTextureFormat.Default);

		camera.targetTexture = tex;

		camera.Render();

		camera.targetTexture = null;

		RenderImage(tex, mRT);

		RenderTexture.ReleaseTemporary(tex);

		return mRT;

	}

	[ContextMenu("Sample")]

	public void Sample()

	{

		var tex = GetComponent<UITexture>();

		tex.mainTexture = Generate();

	}

}

Shader "Hidden/BlurEffectConeTap" {

	Properties { _MainTex ("", any) = "" {} }

	SubShader {

		Pass {

			ZTest Always Cull Off ZWrite Off Fog { Mode Off }

			SetTexture [_MainTex] {constantColor (0,0,0,0.25) combine texture * constant alpha}

			SetTexture [_MainTex] {constantColor (0,0,0,0.25) combine texture * constant + previous}

			SetTexture [_MainTex] {constantColor (0,0,0,0.25) combine texture * constant + previous}

			SetTexture [_MainTex] {constantColor (0,0,0,0.25) combine texture * constant + previous}

		}

	}

	CGINCLUDE

	#include "UnityCG.cginc"

	struct v2f {

		float4 pos : SV_POSITION;

		half2 uv : TEXCOORD0;

		half2 taps[4] : TEXCOORD1;

	};

	sampler2D _MainTex;

	half4 _MainTex_TexelSize;

	half4 _BlurOffsets;

	v2f vert( appdata_img v ) {

		v2f o;

		o.pos = mul(UNITY_MATRIX_MVP, v.vertex);

		o.uv = v.texcoord - _BlurOffsets.xy * _MainTex_TexelSize.xy; // hack, see BlurEffect.cs for the reason for this. let's make a new blur effect soon

		o.taps[0] = o.uv + _MainTex_TexelSize * _BlurOffsets.xy;

		o.taps[1] = o.uv - _MainTex_TexelSize * _BlurOffsets.xy;

		o.taps[2] = o.uv + _MainTex_TexelSize * _BlurOffsets.xy * half2(1,-1);

		o.taps[3] = o.uv - _MainTex_TexelSize * _BlurOffsets.xy * half2(1,-1);

		return o;

	}

	half4 frag(v2f i) : SV_Target {

		half4 color = tex2D(_MainTex, i.taps[0]);

		color += tex2D(_MainTex, i.taps[1]);

		color += tex2D(_MainTex, i.taps[2]);

		color += tex2D(_MainTex, i.taps[3]);

		return color * 0.25;

	}

	ENDCG

	SubShader {

		 Pass {

			  ZTest Always Cull Off ZWrite Off

			  Fog { Mode off }      

			  CGPROGRAM

			  #pragma fragmentoption ARB_precision_hint_fastest

			  #pragma vertex vert

			  #pragma fragment frag

			  ENDCG

		  }

	}

	Fallback off

}