float time = 0;

sampler2D image : register(s0);


float4 main( float4 Pos : POSITION,
	           float2 texCoord: TEXCOORD0) : COLOR 
{
	float4 img = tex2D(image, texCoord);

	// convert to gray 
	float4 sum = dot(img, float4(0.30f, 0.59f, 0.11f, 0.0f));
	
	sum.a = img.a; // keep alpha
	return sum;
}