//**************************************************************************/
// 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.
//**************************************************************************/

// World-view-projection transformation.
uniform mat4 gWVPXf : WorldViewProjection;

uniform vec4 gUVTransform : RelativeViewportDimensions;

// The source texture
uniform texture2D gSourceTex : SourceTexture;

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

uniform float gBrightThreshold = 0.8f;

// Vertex shader input structure.
attribute VS_INPUT
{
    vec4 Pos: POSITION;
    vec2 UV: TEXCOORD0;
};

// Vertex shader output structure.
attribute VS_TO_PS
{
    vec2 VSUV: TEXCOORD0;
};

// Vertex shader.
GLSLShader VS_Threshold
{
	void main()
	{
        gl_Position = gWVPXf*Pos;
		
		// Pass the texture coordinates unchanged.
		VSUV = UV;
	}
}

// Pixel shader output structure.
attribute pixelOut
{
    vec4 colorOut: COLOR0;
}

// Pixel shader.
GLSLShader PS_Threshold
{
	void main()
	{
		vec4 val = texture2D(gSourceSamp, VSUV * gUVTransform.zw + gUVTransform.xy);

		vec4 brightnessFactor = vec4(0.212671f, 0.715160f, 0.072169f, 1.0f);
		float brightness = dot(brightnessFactor.xyz, val.xyz);
		if( brightness > gBrightThreshold)
			colorOut = vec4(val.xyz, 1.0f);
		else
			colorOut = vec4(0.0f, 0.0f, 0.0f, 1.0f);
	}
}

// The main technique.
technique Main
{
    pass p0
    {
        VertexShader (in VS_INPUT, out VS_TO_PS) = VS_Threshold;
        PixelShader (in VS_TO_PS, out pixelOut) = PS_Threshold;
    }
}