//**************************************************************************/
// Copyright 2014 Autodesk, Inc.
// All rights reserved.
// Use of this software is subject to the terms of the Autodesk license
// agreement provided at the time of installation or download, or which
// otherwise accompanies this software in either electronic or hard copy form.
//**************************************************************************/

#include "Common.ogsfh"

// The source texture
uniform texture2D gSourceTex : SourceTexture
<
    string UIName = "Source Texture";
>;

// Sampler of source texture
uniform sampler2D gSourceSamp = sampler_state
{
    Texture = <gSourceTex>;
};

// The 2nd source texture
uniform texture2D gSourceTex2 : SourceTexture2
<
    string UIName = "Source Texture 2";
>;

// Sampler of 2nd source texture
uniform sampler2D gSourceSamp2 = sampler_state
{
    Texture = <gSourceTex2>;
};

uniform vec4 gUVTransform : RelativeViewportDimensions;
uniform vec2 gBasePos = { 0.0f, 0.0f };

GLSLShader PS_Interlace
{
	void main()
	{
		float screenPosY = (1.0f - VSUV[1]) * gScreenSize[1];
		int ypos = int(trunc( screenPosY )) + int(trunc(gBasePos[1]));

		vec4 result;
		if ( ypos % 2 != 0 ) 
		{ 
			result = texture2D(gSourceSamp, VSUV * gUVTransform.zw + gUVTransform.xy);
		} 
		else
		{
			result = texture2D(gSourceSamp2, VSUV * gUVTransform.zw + gUVTransform.xy);
		}

		colorOut = result;
	}
}

technique Main
{
    pass p0
    {
        VertexShader (in VS_INPUT_ScreenQuad, out VS_TO_PS_ScreenQuad) = VS_ScreenQuad;
        PixelShader (in VS_TO_PS_ScreenQuad, out pixelOut) = PS_Interlace;
    }
}