float toLuma( vec3 pRGB )
{
	return( ( pRGB.r * 0.2126 ) + ( pRGB.g * 0.7152 ) + ( pRGB.b * 0.0722 ) );
}

varying vec2 vTexST;

void main()
{
	gl_Position = ftransform();
	
	vTexST= gl_MultiTexCoord0.st;
}

uniform sampler2D uTex;
uniform float uLumaKeyMin;
uniform float uLumaKeyMax;

varying vec2 vTexST;

void main()
{
	float		Luma  = toLuma( texture2D( tex0, tex0ST ).rgb );
	
	if( Luma < uLumaKeyMin || Luma > uLumaKeyMax )
	{
		discard;
	}
	
	gl_FragColor = texture2D( tex0, tex0ST );
}