using UnityEngine;
using System.Collections;


[ExecuteInEditMode]
[RequireComponent (typeof(Camera))]
[AddComponentMenu ("Image Effects/Other/Screen Overlay")]
class ScreenOverlay : PostEffectsBase {
    internal enum OverlayBlendMode {
		Additive = 0,
		ScreenBlend = 1,
		Multiply = 2,
        Overlay = 3,
        AlphaBlend = 4,	
	}
	
	public OverlayBlendMode blendMode = OverlayBlendMode.Overlay;
	public float intensity = 1.0f;
	public Texture2D texture = null;
			
	public Shader overlayShader = null;
	private Material overlayMaterial = null;


    public override bool CheckResources (){
		 CheckSupport (false);
		
		overlayMaterial = CheckShaderAndCreateMaterial (overlayShader, overlayMaterial);
		
		if 	(!isSupported)
			ReportAutoDisable ();
		return isSupported;
	}
	
	void OnRenderImage ( RenderTexture source ,   RenderTexture destination  ){		
		if (CheckResources() == false) {
			Graphics.Blit (source, destination);
			return;
		}

		Vector4 UV_Transform = new  Vector4(1, 0, 0, 1);
		
		#if UNITY_WP8
		// WP8 has no OS support for rotating screen with device orientation,
		// so we do those transformations ourselves.
		if (Screen.orientation == ScreenOrientation.LandscapeLeft) {
			UV_Transform = new Vector4(0, -1, 1, 0);
		}
		if (Screen.orientation == ScreenOrientation.LandscapeRight) {
			UV_Transform = new Vector4(0, 1, -1, 0);
		}
		if (Screen.orientation == ScreenOrientation.PortraitUpsideDown) {
			UV_Transform = new Vector4(-1, 0, 0, -1);
		}	
		#endif
		
		overlayMaterial.SetVector("_UV_Transform", UV_Transform);
		overlayMaterial.SetFloat ("_Intensity", intensity);
		overlayMaterial.SetTexture ("_Overlay", texture);
		Graphics.Blit (source, destination, overlayMaterial, (int) blendMode);
	}
}