using UnityEngine;
using System.Collections;



[ExecuteInEditMode]
[RequireComponent (typeof(Camera))]
[AddComponentMenu ("Image Effects/Rendering/Sun Shafts")]
public class SunShafts : PostEffectsBase {
    public enum SunShaftsResolution {
    Low = 0,
    Normal = 1,
	High = 2,
}

    public enum ShaftsScreenBlendMode {
	Screen = 0,
	Add = 1,	
}	
		
	
	public SunShaftsResolution resolution = SunShaftsResolution.Normal;
	public ShaftsScreenBlendMode screenBlendMode = ShaftsScreenBlendMode.Screen;
	
	public Transform sunTransform;
	public int radialBlurIterations = 2;
	public Color sunColor = Color.white;
	public Color sunThreshold = new Color(0.87f,0.74f,0.65f);
	public float sunShaftBlurRadius = 2.5f;
	public float sunShaftIntensity = 1.15f;
	
	public float maxRadius = 0.75f;
	
	public bool  useDepthTexture = true;
	
	public Shader sunShaftsShader;
	private Material sunShaftsMaterial;	
	
	public Shader simpleClearShader;
	private Material simpleClearMaterial;


    public override bool CheckResources (){	
		 CheckSupport (useDepthTexture);
		
		sunShaftsMaterial = CheckShaderAndCreateMaterial (sunShaftsShader, sunShaftsMaterial);
		simpleClearMaterial = CheckShaderAndCreateMaterial (simpleClearShader, simpleClearMaterial);
		
		if(!isSupported)
			ReportAutoDisable ();
		return isSupported;				
	}
	
	void OnRenderImage ( RenderTexture source ,   RenderTexture destination  ){	
		if(CheckResources()==false) {
			Graphics.Blit (source, destination);
			return;
		}
				
		// we actually need to check this every frame
		if(useDepthTexture)
			GetComponent<Camera>().depthTextureMode |= DepthTextureMode.Depth;	
		
        int divider = 4;
        if (resolution == SunShaftsResolution.Normal)
            divider = 2;
        else if (resolution == SunShaftsResolution.High)
            divider = 1;
            
		Vector3 v = Vector3.one * 0.5f;
		if (sunTransform)
			v = GetComponent<Camera>().WorldToViewportPoint (sunTransform.position);
		else 
			v = new Vector3(0.5f, 0.5f, 0.0f);

		int rtW = source.width / divider;
		int rtH = source.height / divider;
			
		RenderTexture lrColorB;
        RenderTexture lrDepthBuffer = RenderTexture.GetTemporary (rtW, rtH, 0);
		
		// mask out everything except the skybox
		// we have 2 methods, one of which requires depth buffer support, the other one is just comparing images
		
		sunShaftsMaterial.SetVector ("_BlurRadius4", new Vector4 (1.0f, 1.0f, 0.0f, 0.0f) * sunShaftBlurRadius );
		sunShaftsMaterial.SetVector ("_SunPosition", new Vector4 (v.x, v.y, v.z, maxRadius));
		sunShaftsMaterial.SetVector ("_SunThreshold", sunThreshold);
		
		if (!useDepthTexture) {
			var format= GetComponent<Camera>().hdr ? RenderTextureFormat.DefaultHDR: RenderTextureFormat.Default;
			RenderTexture tmpBuffer = RenderTexture.GetTemporary (source.width, source.height, 0, format);					
			RenderTexture.active = tmpBuffer;
			GL.ClearWithSkybox (false, GetComponent<Camera>());
			
			sunShaftsMaterial.SetTexture ("_Skybox", tmpBuffer);
			Graphics.Blit (source, lrDepthBuffer, sunShaftsMaterial, 3);		
			RenderTexture.ReleaseTemporary (tmpBuffer);				
		}
		else {		
			Graphics.Blit (source, lrDepthBuffer, sunShaftsMaterial, 2);
		}
				
        // paint a small black small border to get rid of clamping problems
		DrawBorder (lrDepthBuffer, simpleClearMaterial);
		        			
		// radial blur:
						
		radialBlurIterations = Mathf.Clamp (radialBlurIterations, 1, 4);
				
		float ofs = sunShaftBlurRadius * (1.0f / 768.0f);
		
		sunShaftsMaterial.SetVector ("_BlurRadius4", new Vector4 (ofs, ofs, 0.0f, 0.0f));			
		sunShaftsMaterial.SetVector ("_SunPosition", new Vector4 (v.x, v.y, v.z, maxRadius));				
				
		for (int it2 = 0; it2 < radialBlurIterations; it2++ ) {
			// each iteration takes 2 * 6 samples
			// we update _BlurRadius each time to cheaply get a very smooth look
			
			lrColorB = RenderTexture.GetTemporary (rtW, rtH, 0);
			Graphics.Blit (lrDepthBuffer, lrColorB, sunShaftsMaterial, 1);
			RenderTexture.ReleaseTemporary (lrDepthBuffer);
			ofs = sunShaftBlurRadius * (((it2 * 2.0f + 1.0f) * 6.0f)) / 768.0f;
			sunShaftsMaterial.SetVector ("_BlurRadius4", new Vector4 (ofs, ofs, 0.0f, 0.0f) );			
			
			lrDepthBuffer = RenderTexture.GetTemporary (rtW, rtH, 0);
			Graphics.Blit (lrColorB, lrDepthBuffer, sunShaftsMaterial, 1);		
			RenderTexture.ReleaseTemporary (lrColorB);
			ofs = sunShaftBlurRadius * (((it2 * 2.0f + 2.0f) * 6.0f)) / 768.0f;			
			sunShaftsMaterial.SetVector ("_BlurRadius4", new Vector4 (ofs, ofs, 0.0f, 0.0f) );
		}		
		
		// put together:
		
		if (v.z >= 0.0f)
			sunShaftsMaterial.SetVector ("_SunColor", new Vector4 (sunColor.r, sunColor.g, sunColor.b, sunColor.a) * sunShaftIntensity);
		else
			sunShaftsMaterial.SetVector ("_SunColor", Vector4.zero); // no backprojection !
		sunShaftsMaterial.SetTexture ("_ColorBuffer", lrDepthBuffer);
		Graphics.Blit (source, destination, sunShaftsMaterial, (screenBlendMode == ShaftsScreenBlendMode.Screen) ? 0 : 4); 	
		
		RenderTexture.ReleaseTemporary (lrDepthBuffer);
	}
}