//**************************************************************************/
// Copyright (c) 2011 Autodesk, Inc.
// All rights reserved.
// 
// These coded instructions, statements, and computer programs contain
// unpublished proprietary information written by Autodesk, Inc., and are
// protected by Federal copyright law. They may not be disclosed to third
// parties or copied or duplicated in any form, in whole or in part, without
// the prior written consent of Autodesk, Inc.

#include "Common.cgh"

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

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

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

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

float4 gUVTransform : RelativeViewportDimensions;
float2 gBasePos = { 0.0f, 0.0f };

float4 PS_CheckerBoard(VS_TO_PS_ScreenQuad In) : COLOR0
{
	float1 screenPosX = (In.UV[0])*gScreenSize[0];
	float1 screenPosY = (1.0 - In.UV[1]) * gScreenSize[1]; 
	int xpos = int(trunc( screenPosX )) + int(trunc(gBasePos[0]));
	int ypos = int(trunc( screenPosY )) + int(trunc(gBasePos[1]));

	float4 result;
	if ( ypos % 2 != 0 ) {  
		if ( xpos % 2 == 0 ) {  
			result = tex2D(gSourceSamp, In.UV * gUVTransform.zw + gUVTransform.xy);
		} else { 
			result = tex2D(gSourceSamp2, In.UV * gUVTransform.zw + gUVTransform.xy);
		} 
	} else { 
		if ( xpos % 2 == 0 ) {  
			result = tex2D(gSourceSamp2, In.UV * gUVTransform.zw + gUVTransform.xy);
		} else {  
			result = tex2D(gSourceSamp, In.UV * gUVTransform.zw + gUVTransform.xy);
		} 
	}
    return result;
}

technique Main
{
    pass p0
    {
        VertexShader = compile glslv VS_ScreenQuad();
        PixelShader = compile glslf PS_CheckerBoard();
    }
}